The Experts below are selected from a list of 2085 Experts worldwide ranked by ideXlab platform

Kayoko Iwao - One of the best experts on this subject based on the ideXlab platform.

  • protection against dynorphin 1 8 hydrolysis in membrane preparations by the combination of amastatin captopril and phosphoramidon
    Journal of Pharmacology and Experimental Therapeutics, 1998
    Co-Authors: Toyokazu Hiranuma, Masayuki Kanai, Yoshiharu Arai, Ken Kitamura, Takao Taniguchi, Kayoko Iwao
    Abstract:

    The amounts of dynorphin-(1–8) [dyn-(1–8)] and its seven hydrolysis products, Y, YG, YGG, YGGF, YGGFL, YGGFLR and YGGFLRR, were estimated after incubating dyn-(1–8) with a membrane fraction from either guinea-pig ileum or striatum for various times at 37°C. The major hydrolysis products during the initial 5-min incubation were YGGFLR and Y, which indicates that dipeptidyl carboxypeptidase and Aminopeptidase activities were mainly involved in the hydrolysis. After 60 min of incubation, dyn-(1–8) was completely hydrolyzed in both membrane preparations. When the ileal and the striatal preparations were incubated for 60 min in the presence of both captopril, a dipeptidyl carboxypeptidase Inhibitor, and amastatin, an Aminopeptidase Inhibitor, 63.8 and 49.3% of dyn-(1–8), respectively, were hydrolyzed. The YGG fragment was the major hydrolysis product in both preparations. When the ileal and the striatal membrane fractions were incubated with dyn-(1–8) in the presence of three peptidase Inhibitors, captopril, amastatin and phosphoramidon (an Inhibitor of endopeptidase-24.11), approximately 95% of the opioid octapeptide remained intact in both cases. This shows that dyn-(1–8) was almost exclusively hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, the Ke (equilibrium dissociation constant) values of selective antagonists against dyn-(1–8) and its initial main hydrolysis product YGGFLR in two isolated preparations pretreated with the three peptidase Inhibitors indicate that the latter acts on mu receptors in guinea pig ileum but delta receptors in mouse vas deferens and the former acts on kappa receptors in both preparations. It is indicated, therefore, that in the absence of peptidase Inhibitors endogenously released dyn-(1–8) acts either through dyn-(1–8) itself on kappa receptors or through YGGFLR on mu or delta receptors depending on both the three peptidase activities and the three receptor type densities at the target synaptic membrane.

  • effects of three peptidase Inhibitors amastatin captopril and phosphoramidon on the hydrolysis of met5 enkephalin arg6 phe7 and other opioid peptides
    Naunyn-schmiedebergs Archives of Pharmacology, 1998
    Co-Authors: Toyokazu Hiranuma, Raita Tamaki, Masayuki Kanai, Kazuhito Akahori, Ken Kitamura, Takao Taniguchi, Tomomi Kobayashi, Kayoko Iwao
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Phe7 (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37° C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the Aminopeptidase Inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I Inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase Inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu5]-enkephalin (leu-enk), α- and β-neoendorphins (α- and β-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase Inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: α-neoend, β-neoend, and dyn B.

  • Effects of three peptidase Inhibitors, amastatin, captopril and phosphoramidon, on the hydrolysis of [Met5]-enkephalin-Arg6-Phe7 and other opioid peptides
    Naunyn-Schmiedeberg's archives of pharmacology, 1998
    Co-Authors: Toyokazu Hiranuma, Kayoko Iwao, Raita Tamaki, Masayuki Kanai, Kazuhito Akahori, Ken Kitamura, Takao Taniguchi, Tomomi Kobayashi, Tetsuo Oka
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Phe7 (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37 degrees C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the Aminopeptidase Inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I Inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase Inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu5]-enkephalin (leu-enk), alpha- and beta-neoendorphins (alpha- and beta-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase Inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: alpha-neoend, beta-neoend, and dyn B.

  • almost complete protection from met5 enkephalin arg6 gly7 leu8 met enk rgl hydrolysis in membrane preparations by the combination of amastatin captopril and phosphoramidon
    Journal of Pharmacology and Experimental Therapeutics, 1997
    Co-Authors: Toyokazu Hiranuma, Kayoko Iwao, Ken Kitamura, Teruhiko Matsumiya
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Gly7-Leu8(met-enk-RGL) and its seven hydrolysis products—Y, YG, YGG, YGGF, YGGFM, YGGFMR, and YGGFMRG—were estimated after incubating met-enk-RGL with a membrane fraction from either guinea pig ileum or striatum for various times at 37°C. After 15 min of incubation, met-enk-RGL was completely hydrolyzed in both the ileal and the striatal membrane preparations. The major hydrolysis products were YGGFMR, YGGF and Y, which indicates that dipeptidyl carboxypeptidase and Aminopeptidase activities were mainly involved in the hydrolysis. Additionally, even when the ileal and the striatal preparations were incubated for 60 min in the presence of both captopril, a dipeptidyl carboxypeptidase Inhibitor, and amastatin, an Aminopeptidase Inhibitor, 24% and 44% of enkephalin octapeptide, respectively, were hydrolyzed. The YGG fragment was the major hydrolysis product in both preparations. When the ileal and the striatal membrane fractions were incubated with met-enk-RGL in the presence of three peptidase Inhibitors—captopril, amastatin, and phosphoramidon (an Inhibitor of endopeptidase-24.11)—approximately 95% of the enkephalin octapeptide, remained intact in both cases. This shows that met-enk-RGL was almost exclusively hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. We also reported the potencies of several opioids relative to that of met-enk-RGL in guinea pig ileum pretreated with the three peptidase Inhibitors.

Toyokazu Hiranuma - One of the best experts on this subject based on the ideXlab platform.

  • protection against dynorphin 1 8 hydrolysis in membrane preparations by the combination of amastatin captopril and phosphoramidon
    Journal of Pharmacology and Experimental Therapeutics, 1998
    Co-Authors: Toyokazu Hiranuma, Masayuki Kanai, Yoshiharu Arai, Ken Kitamura, Takao Taniguchi, Kayoko Iwao
    Abstract:

    The amounts of dynorphin-(1–8) [dyn-(1–8)] and its seven hydrolysis products, Y, YG, YGG, YGGF, YGGFL, YGGFLR and YGGFLRR, were estimated after incubating dyn-(1–8) with a membrane fraction from either guinea-pig ileum or striatum for various times at 37°C. The major hydrolysis products during the initial 5-min incubation were YGGFLR and Y, which indicates that dipeptidyl carboxypeptidase and Aminopeptidase activities were mainly involved in the hydrolysis. After 60 min of incubation, dyn-(1–8) was completely hydrolyzed in both membrane preparations. When the ileal and the striatal preparations were incubated for 60 min in the presence of both captopril, a dipeptidyl carboxypeptidase Inhibitor, and amastatin, an Aminopeptidase Inhibitor, 63.8 and 49.3% of dyn-(1–8), respectively, were hydrolyzed. The YGG fragment was the major hydrolysis product in both preparations. When the ileal and the striatal membrane fractions were incubated with dyn-(1–8) in the presence of three peptidase Inhibitors, captopril, amastatin and phosphoramidon (an Inhibitor of endopeptidase-24.11), approximately 95% of the opioid octapeptide remained intact in both cases. This shows that dyn-(1–8) was almost exclusively hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, the Ke (equilibrium dissociation constant) values of selective antagonists against dyn-(1–8) and its initial main hydrolysis product YGGFLR in two isolated preparations pretreated with the three peptidase Inhibitors indicate that the latter acts on mu receptors in guinea pig ileum but delta receptors in mouse vas deferens and the former acts on kappa receptors in both preparations. It is indicated, therefore, that in the absence of peptidase Inhibitors endogenously released dyn-(1–8) acts either through dyn-(1–8) itself on kappa receptors or through YGGFLR on mu or delta receptors depending on both the three peptidase activities and the three receptor type densities at the target synaptic membrane.

  • effects of three peptidase Inhibitors amastatin captopril and phosphoramidon on the hydrolysis of met5 enkephalin arg6 phe7 and other opioid peptides
    Naunyn-schmiedebergs Archives of Pharmacology, 1998
    Co-Authors: Toyokazu Hiranuma, Raita Tamaki, Masayuki Kanai, Kazuhito Akahori, Ken Kitamura, Takao Taniguchi, Tomomi Kobayashi, Kayoko Iwao
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Phe7 (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37° C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the Aminopeptidase Inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I Inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase Inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu5]-enkephalin (leu-enk), α- and β-neoendorphins (α- and β-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase Inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: α-neoend, β-neoend, and dyn B.

  • Effects of three peptidase Inhibitors, amastatin, captopril and phosphoramidon, on the hydrolysis of [Met5]-enkephalin-Arg6-Phe7 and other opioid peptides
    Naunyn-Schmiedeberg's archives of pharmacology, 1998
    Co-Authors: Toyokazu Hiranuma, Kayoko Iwao, Raita Tamaki, Masayuki Kanai, Kazuhito Akahori, Ken Kitamura, Takao Taniguchi, Tomomi Kobayashi, Tetsuo Oka
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Phe7 (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37 degrees C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the Aminopeptidase Inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I Inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase Inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu5]-enkephalin (leu-enk), alpha- and beta-neoendorphins (alpha- and beta-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase Inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: alpha-neoend, beta-neoend, and dyn B.

  • almost complete protection from met5 enkephalin arg6 gly7 leu8 met enk rgl hydrolysis in membrane preparations by the combination of amastatin captopril and phosphoramidon
    Journal of Pharmacology and Experimental Therapeutics, 1997
    Co-Authors: Toyokazu Hiranuma, Kayoko Iwao, Ken Kitamura, Teruhiko Matsumiya
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Gly7-Leu8(met-enk-RGL) and its seven hydrolysis products—Y, YG, YGG, YGGF, YGGFM, YGGFMR, and YGGFMRG—were estimated after incubating met-enk-RGL with a membrane fraction from either guinea pig ileum or striatum for various times at 37°C. After 15 min of incubation, met-enk-RGL was completely hydrolyzed in both the ileal and the striatal membrane preparations. The major hydrolysis products were YGGFMR, YGGF and Y, which indicates that dipeptidyl carboxypeptidase and Aminopeptidase activities were mainly involved in the hydrolysis. Additionally, even when the ileal and the striatal preparations were incubated for 60 min in the presence of both captopril, a dipeptidyl carboxypeptidase Inhibitor, and amastatin, an Aminopeptidase Inhibitor, 24% and 44% of enkephalin octapeptide, respectively, were hydrolyzed. The YGG fragment was the major hydrolysis product in both preparations. When the ileal and the striatal membrane fractions were incubated with met-enk-RGL in the presence of three peptidase Inhibitors—captopril, amastatin, and phosphoramidon (an Inhibitor of endopeptidase-24.11)—approximately 95% of the enkephalin octapeptide, remained intact in both cases. This shows that met-enk-RGL was almost exclusively hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. We also reported the potencies of several opioids relative to that of met-enk-RGL in guinea pig ileum pretreated with the three peptidase Inhibitors.

Ken Kitamura - One of the best experts on this subject based on the ideXlab platform.

  • protection against dynorphin 1 8 hydrolysis in membrane preparations by the combination of amastatin captopril and phosphoramidon
    Journal of Pharmacology and Experimental Therapeutics, 1998
    Co-Authors: Toyokazu Hiranuma, Masayuki Kanai, Yoshiharu Arai, Ken Kitamura, Takao Taniguchi, Kayoko Iwao
    Abstract:

    The amounts of dynorphin-(1–8) [dyn-(1–8)] and its seven hydrolysis products, Y, YG, YGG, YGGF, YGGFL, YGGFLR and YGGFLRR, were estimated after incubating dyn-(1–8) with a membrane fraction from either guinea-pig ileum or striatum for various times at 37°C. The major hydrolysis products during the initial 5-min incubation were YGGFLR and Y, which indicates that dipeptidyl carboxypeptidase and Aminopeptidase activities were mainly involved in the hydrolysis. After 60 min of incubation, dyn-(1–8) was completely hydrolyzed in both membrane preparations. When the ileal and the striatal preparations were incubated for 60 min in the presence of both captopril, a dipeptidyl carboxypeptidase Inhibitor, and amastatin, an Aminopeptidase Inhibitor, 63.8 and 49.3% of dyn-(1–8), respectively, were hydrolyzed. The YGG fragment was the major hydrolysis product in both preparations. When the ileal and the striatal membrane fractions were incubated with dyn-(1–8) in the presence of three peptidase Inhibitors, captopril, amastatin and phosphoramidon (an Inhibitor of endopeptidase-24.11), approximately 95% of the opioid octapeptide remained intact in both cases. This shows that dyn-(1–8) was almost exclusively hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, the Ke (equilibrium dissociation constant) values of selective antagonists against dyn-(1–8) and its initial main hydrolysis product YGGFLR in two isolated preparations pretreated with the three peptidase Inhibitors indicate that the latter acts on mu receptors in guinea pig ileum but delta receptors in mouse vas deferens and the former acts on kappa receptors in both preparations. It is indicated, therefore, that in the absence of peptidase Inhibitors endogenously released dyn-(1–8) acts either through dyn-(1–8) itself on kappa receptors or through YGGFLR on mu or delta receptors depending on both the three peptidase activities and the three receptor type densities at the target synaptic membrane.

  • effects of three peptidase Inhibitors amastatin captopril and phosphoramidon on the hydrolysis of met5 enkephalin arg6 phe7 and other opioid peptides
    Naunyn-schmiedebergs Archives of Pharmacology, 1998
    Co-Authors: Toyokazu Hiranuma, Raita Tamaki, Masayuki Kanai, Kazuhito Akahori, Ken Kitamura, Takao Taniguchi, Tomomi Kobayashi, Kayoko Iwao
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Phe7 (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37° C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the Aminopeptidase Inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I Inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase Inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu5]-enkephalin (leu-enk), α- and β-neoendorphins (α- and β-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase Inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: α-neoend, β-neoend, and dyn B.

  • Effects of three peptidase Inhibitors, amastatin, captopril and phosphoramidon, on the hydrolysis of [Met5]-enkephalin-Arg6-Phe7 and other opioid peptides
    Naunyn-Schmiedeberg's archives of pharmacology, 1998
    Co-Authors: Toyokazu Hiranuma, Kayoko Iwao, Raita Tamaki, Masayuki Kanai, Kazuhito Akahori, Ken Kitamura, Takao Taniguchi, Tomomi Kobayashi, Tetsuo Oka
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Phe7 (met-enk-RF) and its six hydrolysis products: Y, YG, YGG, YGGF, YGGFM, and YGGFMR were estimated after incubating met-enk-RF with either a guinea-pig ileal or striatal membrane fraction for various times at 37 degrees C. After 45 min incubation with either ileal or striatal membranes, met-enk-RF was completely hydrolyzed, yielding Y as the major product. Incubation with either membrane preparation for 60 min in the presence of the Aminopeptidase Inhibitor amastatin hydrolyzed 90 or 92% of met-enk-RF, respectively, with YGG being the major product. If the dipeptidyl carboxypeptidase I Inhibitor captopril is also included in the incubation, met-enk-RF hydrolysis decreases by about half for both membranes, with YGG remaining the major product. Inclusion of three peptidase Inhibitors, amastatin, captopril, and phosphoramidon (inhibition of endopeptidase-24.11) further reduced met-enk-hydrolysis, with 87% or more remaining intact. This shows that met-enk-RF was mainly hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. Additionally, estimations of [Leu5]-enkephalin (leu-enk), alpha- and beta-neoendorphins (alpha- and beta-neoends), and dynorphin B (dyn B) contents after incubating the individual peptides with striatal membrane for 60 min in the presence of the three peptidase Inhibitors showed that 98, 32, 5, and 23%, respectively, remained intact. Our previous studies together with the data obtained here show that one group of endogenous opioid peptides: met-enk, leu-enk, met-enk-RF, met-enk-RGL, and dyn A-(1-8) are largely or almost exclusively hydrolyzed by the three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I, and phosphoramidon-sensitive endopeptidase-24.11, and indicate that an unidentified fourth enzyme(s) is involved in the hydrolysis of another group of peptides: alpha-neoend, beta-neoend, and dyn B.

  • almost complete protection from met5 enkephalin arg6 gly7 leu8 met enk rgl hydrolysis in membrane preparations by the combination of amastatin captopril and phosphoramidon
    Journal of Pharmacology and Experimental Therapeutics, 1997
    Co-Authors: Toyokazu Hiranuma, Kayoko Iwao, Ken Kitamura, Teruhiko Matsumiya
    Abstract:

    The contents of [Met5]-enkephalin-Arg6-Gly7-Leu8(met-enk-RGL) and its seven hydrolysis products—Y, YG, YGG, YGGF, YGGFM, YGGFMR, and YGGFMRG—were estimated after incubating met-enk-RGL with a membrane fraction from either guinea pig ileum or striatum for various times at 37°C. After 15 min of incubation, met-enk-RGL was completely hydrolyzed in both the ileal and the striatal membrane preparations. The major hydrolysis products were YGGFMR, YGGF and Y, which indicates that dipeptidyl carboxypeptidase and Aminopeptidase activities were mainly involved in the hydrolysis. Additionally, even when the ileal and the striatal preparations were incubated for 60 min in the presence of both captopril, a dipeptidyl carboxypeptidase Inhibitor, and amastatin, an Aminopeptidase Inhibitor, 24% and 44% of enkephalin octapeptide, respectively, were hydrolyzed. The YGG fragment was the major hydrolysis product in both preparations. When the ileal and the striatal membrane fractions were incubated with met-enk-RGL in the presence of three peptidase Inhibitors—captopril, amastatin, and phosphoramidon (an Inhibitor of endopeptidase-24.11)—approximately 95% of the enkephalin octapeptide, remained intact in both cases. This shows that met-enk-RGL was almost exclusively hydrolyzed by three enzymes, amastatin-sensitive Aminopeptidase, captopril-sensitive dipeptidyl carboxypeptidase I and phosphoramidon-sensitive endopeptidase-24.11, in both ileal and striatal membranes. We also reported the potencies of several opioids relative to that of met-enk-RGL in guinea pig ileum pretreated with the three peptidase Inhibitors.

Stephen G. Weber - One of the best experts on this subject based on the ideXlab platform.

  • higher Aminopeptidase activity determined by electroosmotic push pull perfusion contributes to selective vulnerability of the hippocampal ca1 region to oxygen glucose deprivation
    ACS Chemical Neuroscience, 2017
    Co-Authors: Stephen G. Weber
    Abstract:

    It has been known for over a century that the hippocampus, the center for learning and memory in the brain, is selectively vulnerable to ischemic damage, with the CA1 being more vulnerable than the CA3. It is also known that leucine enkephalin, or YGGFL, is neuroprotective. We hypothesized that the extracellular hydrolysis of YGGFL may be greater in the CA1 than the CA3, which would lead to the observed difference in susceptibility to ischemia. In rat organotypic hippocampal slice cultures, we estimated the Michaelis constant and the maximum velocity for membrane-bound Aminopeptidase activity in the CA1 and CA3 regions. Using electroosmotic push–pull perfusion and offline capillary liquid chromatography, we inferred enzyme activity based on the production rate of GGFL, a natural and inactive product of the enzymatic hydrolysis of YGGFL. We found nearly 3-fold higher Aminopeptidase activity in the CA1 than the CA3. The Aminopeptidase Inhibitor bestatin significantly reduced hydrolysis of YGGFL in both regi...

  • Higher Aminopeptidase Activity Determined by Electroosmotic Push–Pull Perfusion Contributes to Selective Vulnerability of the Hippocampal CA1 Region to Oxygen Glucose Deprivation
    2017
    Co-Authors: Stephen G. Weber
    Abstract:

    It has been known for over a century that the hippocampus, the center for learning and memory in the brain, is selectively vulnerable to ischemic damage, with the CA1 being more vulnerable than the CA3. It is also known that leucine enkephalin, or YGGFL, is neuroprotective. We hypothesized that the extracellular hydrolysis of YGGFL may be greater in the CA1 than the CA3, which would lead to the observed difference in susceptibility to ischemia. In rat organotypic hippocampal slice cultures, we estimated the Michaelis constant and the maximum velocity for membrane-bound Aminopeptidase activity in the CA1 and CA3 regions. Using electroosmotic push–pull perfusion and offline capillary liquid chromatography, we inferred enzyme activity based on the production rate of GGFL, a natural and inactive product of the enzymatic hydrolysis of YGGFL. We found nearly 3-fold higher Aminopeptidase activity in the CA1 than the CA3. The Aminopeptidase Inhibitor bestatin significantly reduced hydrolysis of YGGFL in both regions by increasing apparent Km. Based on propidium iodide cell death measurements 24 h after oxygen–glucose deprivation, we demonstrate that inhibition of Aminopeptidase activity using bestatin selectively protected CA1 against delayed cell death due to oxygen–glucose deprivation and that this neuroprotection occurs through enkephalin-dependent pathways

Kenichi Kusumoto - One of the best experts on this subject based on the ideXlab platform.

  • erratum to enzymatic properties of the glycine d alanine Aminopeptidase of aspergillus oryzae and its activity profiles in liquid cultured mycelia and solid state rice culture rice koji
    Applied Microbiology and Biotechnology, 2012
    Co-Authors: Junichiro Marui, Mayumi Matsushitamorita, Sawaki Tada, Ryota Hattori, Satoshi Suzuki, Hitoshi Amano, Hiroki Ishida, Youhei Yamagata, Michio Takeuchi, Kenichi Kusumoto
    Abstract:

    The gdaA gene encoding S12 family glycine–d-alanine Aminopeptidase (GdaA) was found in the industrial fungus Aspergillus oryzae. GdaA shares 43% amino acid sequence identity with the d-Aminopeptidase of the Gram-negative bacterium Ochrobactrum anthropi. GdaA purified from an A. oryzae gdaA-overexpressing strain exhibited high d-stereospecificity and efficiently released N-terminal glycine and d-alanine of substrates in a highly specific manner. The optimum pH and temperature were 8 to 9 and 40°C, respectively. This enzyme was stable under alkaline conditions at pH 8 to 11 and relatively resistant to acidic conditions until pH 5.0. The chelating reagent EDTA, serine protease Inhibitors such as AEBSF, benzamidine, TPCK, and TLCK, and the thiol enzyme Inhibitor PCMB inhibited the enzyme. The Aminopeptidase Inhibitor bestatin did not affect the activity. GdaA was largely responsible for intracellular glycine and d-alanine Aminopeptidase activities in A. oryzae during stationary-phase growth in liquid media. In addition, the activity increased in response to the depletion of nitrogen or carbon sources in the growth media, although the GdaA-independent glycine Aminopeptidase activity highly increased simultaneously. Aminopeptidases of A. oryzae attract attention because the enzymatic release of a variety of amino acids and peptides is important for the enhancement of the palatability of fermented foods. GdaA activity was found in extracts of a solid-state rice culture of A. oryzae (rice koji), which is widely used as a starter culture for Japanese traditional fermented foods, and was largely responsible for the glycine and d-alanine Aminopeptidase activity detected at a pH range of 6 to 9.

  • enzymatic properties of the glycine d alanine corrected Aminopeptidase of aspergillus oryzae and its activity profiles in liquid cultured mycelia and solid state rice culture rice koji
    Applied Microbiology and Biotechnology, 2012
    Co-Authors: Junichiro Marui, Mayumi Matsushitamorita, Sawaki Tada, Ryota Hattori, Satoshi Suzuki, Hitoshi Amano, Hiroki Ishida, Youhei Yamagata, Michio Takeuchi, Kenichi Kusumoto
    Abstract:

    The gdaA gene encoding S12 family glycine-D-alanine Aminopeptidase (GdaA) was found in the industrial fungus Aspergillus oryzae. GdaA shares 43% amino acid sequence identity with the D-Aminopeptidase of the Gram-negative bacterium Ochrobactrum anthropi. GdaA purified from an A. oryzae gdaA-overexpressing strain exhibited high D-stereospecificity and efficiently released N-terminal glycine and D-alanine of substrates in a highly specific manner. The optimum pH and temperature were 8 to 9 and 40°C, respectively. This enzyme was stable under alkaline conditions at pH 8 to 11 and relatively resistant to acidic conditions until pH 5.0. The chelating reagent EDTA, serine protease Inhibitors such as AEBSF, benzamidine, TPCK, and TLCK, and the thiol enzyme Inhibitor PCMB inhibited the enzyme. The Aminopeptidase Inhibitor bestatin did not affect the activity. GdaA was largely responsible for intracellular glycine and D-alanine Aminopeptidase activities in A. oryzae during stationary-phase growth in liquid media. In addition, the activity increased in response to the depletion of nitrogen or carbon sources in the growth media, although the GdaA-independent glycine Aminopeptidase activity highly increased simultaneously. Aminopeptidases of A. oryzae attract attention because the enzymatic release of a variety of amino acids and peptides is important for the enhancement of the palatability of fermented foods. GdaA activity was found in extracts of a solid-state rice culture of A. oryzae (rice koji), which is widely used as a starter culture for Japanese traditional fermented foods, and was largely responsible for the glycine and D-alanine Aminopeptidase activity detected at a pH range of 6 to 9.