The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Runguang Zhang - One of the best experts on this subject based on the ideXlab platform.
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purification characterization synthesis in vitro ace inhibition and in vivo antihypertensive activity of bioactive peptides derived from oil palm kernel glutelin 2 hydrolysates
Journal of Functional Foods, 2017Co-Authors: Yajun Zheng, Yan Li, Youlin Zhang, Xiaohui Ruan, Runguang ZhangAbstract:Abstract Palm kernel expeller glutelin-2 hydrolysates (PKEGH) with high ACE-inhibitory activity (80.24%) were obtained by the sequential digestion with alcalase, flavourzyme, pepsin and trypsin assisted by high pressure pretreatment. PKEGH were separated by ultrafiltration, Sephadex G-25 gel chromatography and RP-HPLC. Finally four novel ACE-inhibitory peptides (Ala-Asp-Val-Phe-Asn-Pro-Arg, Val-Val-Leu-Tyr-Lys, Leu-Pro-Ile-Leu-Arg and Val-Ile-Glu-Pro-Arg) were identified, of which Val-Val-Leu-Tyr-Lys showed the highest activity (IC50: 533.9 μM). All the four peptides exhibited potent non-competitive ACE inhibition and relatively good stability against gastrointestinal enzymes digestion. Moreover, these peptides significantly lowered the endothelin-1 content in EA.hy926 cells without significant cytotoxicity, and protected vascular endothelial cells from reactive oxygen species mediated damage. Furthermore, the PKEGH and individual ACE-inhibitory peptides identified from it showed chronic antihypertensive effects in spontaneously hypertensive rats after several days/weeks administration. Result showed that Palm kernel expeller glutelin-2 could be effectively converted to produce ACE-inhibitory or antihypertensive peptides.
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purification characterization synthesis in vitro ace inhibition and in vivo antihypertensive activity of bioactive peptides derived from oil palm kernel glutelin 2 hydrolysates
Journal of Functional Foods, 2017Co-Authors: Yajun Zheng, Youlin Zhang, Xiaohui Ruan, Runguang ZhangAbstract:Abstract Palm kernel expeller glutelin-2 hydrolysates (PKEGH) with high ACE-inhibitory activity (80.24%) were obtained by the sequential digestion with alcalase, flavourzyme, pepsin and trypsin assisted by high pressure pretreatment. PKEGH were separated by ultrafiltration, Sephadex G-25 gel chromatography and RP-HPLC. Finally four novel ACE-inhibitory peptides (Ala-Asp-Val-Phe-Asn-Pro-Arg, Val-Val-Leu-Tyr-Lys, Leu-Pro-Ile-Leu-Arg and Val-Ile-Glu-Pro-Arg) were identified, of which Val-Val-Leu-Tyr-Lys showed the highest activity (IC50: 533.9 μM). All the four peptides exhibited potent non-competitive ACE inhibition and relatively good stability against gastrointestinal enzymes digestion. Moreover, these peptides significantly lowered the endothelin-1 content in EA.hy926 cells without significant cytotoxicity, and protected vascular endothelial cells from reactive oxygen species mediated damage. Furthermore, the PKEGH and individual ACE-inhibitory peptides identified from it showed chronic antihypertensive effects in spontaneously hypertensive rats after several days/weeks administration. Result showed that Palm kernel expeller glutelin-2 could be effectively converted to produce ACE-inhibitory or antihypertensive peptides.
Delbert M Gatlin - One of the best experts on this subject based on the ideXlab platform.
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imbalanced dietary levels of branched chain amino acids affect growth performance and amino acid utilization of juvenile red drum sciaenops ocellatus
Aquaculture, 2018Co-Authors: Sergio Castillo, Delbert M GatlinAbstract:Abstract Imbalanced dietary levels of branched-chain amino acids (BCAAs) are known to produce antagonistic effects in pigs, rats and humans, affecting the concentration of BCAAs in plasma and ultimately depressing growth. In fish, antagonism involving BCAAs has not been fully characterized or understood. The objective of this study was to determine the effects of imbalanced dietary levels of BCAAs on growth performance and amino acid utilization of juvenile red drum. A control diet was prepared by combining lyophilized red drum muscle and crystalline amino acids, while keeping leucine (Leu), isoleucine (Ile) and valine (Val) at the previously quantified minimum dietary requirement levels for red drum. Six experimental diets were prepared by supplementing the control diet with (1) an excess of Leu, (2) an excess of Ile, (3) an excess of Val, (4) an excess of Leu and Ile, (5) an excess of Ile and Val, and (6) an excess of Leu and Val. Red drum juveniles were stocked in 38-L glass aquaria, and diets were fed to fish in triplicate aquaria, twice daily, for 45 d. At the end of the feeding trial, growth performance was evaluated and postprandial levels of BCAAs in plasma were analyzed. Growth performance of red drum was significantly depressed by an excess of dietary Leu, but not by an excess of Ile nor Val. The postprandial concentration of plasma Leu, Ile or Val was significantly higher in fish fed an excess of Leu, Ile or Val, respectively. Postprandial levels of BCAAs in plasma did not indicate that an excess of Leu blocked the intestinal absorption or promoted the catabolism of Ile and/or Val in red drum, as has been reported in other species. However, excess Leu did significantly reduce the postprandial concentration of α-ketoglutarate in plasma, possibly indicating a higher ratio of transamination due to the imbalanced postprandial concentration of BCAAs in plasma. In conclusion, an antagonistic effect due to excess dietary Leu was confirmed in juvenile red drum. This study represents a step forward in understanding the nature of the antagonistic effects among BCAAs in fish.
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dietary requirements for leucine isoleucine and valine branched chain amino acids by juvenile red drum sciaenops ocellatus
Aquaculture Nutrition, 2018Co-Authors: Sergio Castillo, Delbert M GatlinAbstract:The objective of this study was to determine the minimum dietary requirements of the branched-chain amino acids (BCAAs: leucine [Leu], isoleucine [Ile] and valine [Val]) for juvenile red drum, Sciaenops ocellatus. This was accomplished by conducting three independent 49-day feeding trials with juvenile red drum. Experimental diets were prepared by supplementing a basal diet containing 370 g/kg crude protein from red drum muscle and crystalline amino acids with incremental levels of Leu (9.0, 13.0, 17.0, 21.0, 25.0 and 29.0 g/kg of dry diet), Ile (5.0, 8.0, 11.0, 14.0, 17.0 and 20.0 g/kg of dry diet) and Val (6.8, 8.0, 9.2, 10.4, 11.6, 12.8 and 14.0 g/kg of dry diet). Fish were fed to apparent satiation twice daily in each trial, after which growth performance parameters were calculated and body composition and concentrations of BCAAs in plasma were analysed. Incremental levels of dietary Leu, Ile and Val significantly affected weight gain, feed efficiency and protein retention. Analyses of the weight gain data using a broken-line regression model estimated the minimum Leu, Ile and Val requirements for maximum growth of juvenile red drum to be 15.7 ± 1.7 g/kg (±95% confidence interval), 11.1 ± 2.3 g/kg and 12.4 ± 0.6 g/kg of dry diet, respectively.
Yajun Zheng - One of the best experts on this subject based on the ideXlab platform.
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purification characterization synthesis in vitro ace inhibition and in vivo antihypertensive activity of bioactive peptides derived from oil palm kernel glutelin 2 hydrolysates
Journal of Functional Foods, 2017Co-Authors: Yajun Zheng, Yan Li, Youlin Zhang, Xiaohui Ruan, Runguang ZhangAbstract:Abstract Palm kernel expeller glutelin-2 hydrolysates (PKEGH) with high ACE-inhibitory activity (80.24%) were obtained by the sequential digestion with alcalase, flavourzyme, pepsin and trypsin assisted by high pressure pretreatment. PKEGH were separated by ultrafiltration, Sephadex G-25 gel chromatography and RP-HPLC. Finally four novel ACE-inhibitory peptides (Ala-Asp-Val-Phe-Asn-Pro-Arg, Val-Val-Leu-Tyr-Lys, Leu-Pro-Ile-Leu-Arg and Val-Ile-Glu-Pro-Arg) were identified, of which Val-Val-Leu-Tyr-Lys showed the highest activity (IC50: 533.9 μM). All the four peptides exhibited potent non-competitive ACE inhibition and relatively good stability against gastrointestinal enzymes digestion. Moreover, these peptides significantly lowered the endothelin-1 content in EA.hy926 cells without significant cytotoxicity, and protected vascular endothelial cells from reactive oxygen species mediated damage. Furthermore, the PKEGH and individual ACE-inhibitory peptides identified from it showed chronic antihypertensive effects in spontaneously hypertensive rats after several days/weeks administration. Result showed that Palm kernel expeller glutelin-2 could be effectively converted to produce ACE-inhibitory or antihypertensive peptides.
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purification characterization synthesis in vitro ace inhibition and in vivo antihypertensive activity of bioactive peptides derived from oil palm kernel glutelin 2 hydrolysates
Journal of Functional Foods, 2017Co-Authors: Yajun Zheng, Youlin Zhang, Xiaohui Ruan, Runguang ZhangAbstract:Abstract Palm kernel expeller glutelin-2 hydrolysates (PKEGH) with high ACE-inhibitory activity (80.24%) were obtained by the sequential digestion with alcalase, flavourzyme, pepsin and trypsin assisted by high pressure pretreatment. PKEGH were separated by ultrafiltration, Sephadex G-25 gel chromatography and RP-HPLC. Finally four novel ACE-inhibitory peptides (Ala-Asp-Val-Phe-Asn-Pro-Arg, Val-Val-Leu-Tyr-Lys, Leu-Pro-Ile-Leu-Arg and Val-Ile-Glu-Pro-Arg) were identified, of which Val-Val-Leu-Tyr-Lys showed the highest activity (IC50: 533.9 μM). All the four peptides exhibited potent non-competitive ACE inhibition and relatively good stability against gastrointestinal enzymes digestion. Moreover, these peptides significantly lowered the endothelin-1 content in EA.hy926 cells without significant cytotoxicity, and protected vascular endothelial cells from reactive oxygen species mediated damage. Furthermore, the PKEGH and individual ACE-inhibitory peptides identified from it showed chronic antihypertensive effects in spontaneously hypertensive rats after several days/weeks administration. Result showed that Palm kernel expeller glutelin-2 could be effectively converted to produce ACE-inhibitory or antihypertensive peptides.
Michael J Conlon - One of the best experts on this subject based on the ideXlab platform.
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the alyteserins two families of antimicrobial peptides from the skin secretions of the midwife toad alytes obstetricans alytidae
Peptides, 2009Co-Authors: Michael J Conlon, Anni Demandt, Per F. Nielsen, Hubert Vaudry, Jérôme Leprince, Douglas C. WoodhamsAbstract:Abstract Two families of structurally related C-terminally α-amidated antimicrobial peptides have been identified in norepinephrine-stimulated skin secretions of the midwife toad Alytes obstetricans (Alytidae). The alyteserin-1 peptides (Gly-Leu-Lys-(Asp/Glu)-Ile-Phe-Lys-Ala-Gly-Leu-Gly-Ser-Leu-Val-Lys-(Gly/Asn)-Ile-Ala-Ala-His-Val-Ala-(Asn/Ser).NH 2 ) show limited structural similarity to the ascaphins from the skins of frogs of the family Leiopelmatidae. Alyteserin-2a (Ile-Leu-Gly-Lys-Leu-Leu-Ser-Thr-Ala-Ala-Gly-Leu-Leu-Ser-Asn-Leu.NH 2 ) and alyteserin-2b and -2c (Ile-Leu-Gly-Ala-Ile-Leu-Pro-Leu-Val-Ser-Gly-Leu-Leu-Ser-(Asn/Ser)-Lys-Leu.NH 2 ) show limited sequence identity with bombinin H6, present in the skins of frogs of the family Bombinatoridae. The alyteserin-1 peptides show selective growth inhibitory activity against the Gram-negative bacteria Escherichia coli (MIC = 25 μM) whereas alyteserin-2a is more potent against the Gram-positive bacteria Staphylococcus aureus (MIC = 50 μM). The hemolytic activity against human erythrocytes of all peptides tested is relatively weak (LC 50 > 100 μM). The data demonstrate that the frogs belonging to the family Alytidae are among those producing dermal antimicrobial peptides that may represent a component of the animal's system of innate immunity.
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evidence for processing enzymes in the abdominal gland of the newt cynops pyrrhogaster that generate sodefrin from its biosynthetic precursor
Zoological Science, 2007Co-Authors: Tomoaki Nakada, Michael J Conlon, Yoko Ishizuka, Takeo Iwata, Fumiyo Toyoda, Takashi Kato, Sakae KikuyamaAbstract:Sodefrin (Ser-Ile-Pro-Ser-Lys-Asp-Ala-Leu-Leu-Lys) is a female-attracting peptide pheromone secreted by the abdominal gland of the male red-bellied newt, Cynops pyrrhogaster. Sequence analysis of a cDNA encoding sodefrin revealed that the peptide is located in the C-terminal region of its precursor protein (residues 177-186 of preprosodefrin) and extended from its C-terminus by the tripeptide sequence Ile(187)-Ser(188)-Ala(189) and flanked at its N-terminus by Leu(174)-Gly(175)-Arg(176). This suggests that sodefrin is generated by enzymatic cleavage at monobasic (Lys and Arg) sites within the precursor molecule. To demonstrate the presence in the abdominal gland of proteolytic enzymes capable of generating sodefrin, an enzymatic assay was developed using t-butoxycarbo-nyl (Boc)-Leu-Gly-Arg-4methylcoumaryl-7-amide (MCA) and Boc-Leu-Leu-Lys-MCA as synthetic substrates. A crude extract of the abdominal gland hydrolyzed both substrates to liberate 7-amino-4- methylcoumarin, suggesting that enzymes that generate sodefrin from its precursor molecule are present in the gland. The activity in the extract for cleaving Boc-Leu-Gly-Arg-MCA was optimal at pH 9.0 and 45 degrees C and for Boc-Leu-Leu-Lys-MCA at pH 9.0 and 40 degrees C. The effects of a range of specific inhibitors on activities in the extract suggest an involvement of enzymes belonging to the serine protease family. It was also demonstrated that enzymatic activity in an extract of the abdominal glands of sexually developed males was significantly (three- to six-fold; p<0.01) higher than that of sexually undeveloped males.
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characterization of a peptide from skin secretions of male specimens of the frog leptodactylus fallax that stimulates aggression in male frogs
Peptides, 2005Co-Authors: Jay D King, Per F. Nielsen, Louise A Rollinssmith, Anne John, Michael J ConlonAbstract:During the breeding season of the mountain chicken frog Leptodactylus fallax, fighting between males results in the emergence of dominant animals that subsequently attract females to nesting sites. A peptide, termed Leptodactylus aggression-stimulating peptide (LASP), was isolated from norepinephrine-stimulated skin secretions from male specimens of L. fallax that was not present in skin secretions obtained from females. The primary structure of the peptide was established as: Gly-Leu-Trp-Asp-Asp-Leu-Lys-Ala-Ala-Ala-Lys-Lys-Val-Val-Ser-Ser-Leu-Ala-Ser-Ala-Ala-Ile-Glu-Lys-Leu NH2. LASP had no pheromone-like action on females but had a chemoattractive effect on males and stimulated aggressive behaviors, such as rearing and leaping. It is suggested that this peptide may play an important role in initiating the competitive male-male interactions that are associated with the onset of reproductive behavior in L. fallax.
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primary structure of insulin from the african lungfish protopterus annectens
General and Comparative Endocrinology, 1997Co-Authors: Michael J Conlon, James E Platz, Per F. Nielsen, Hubert Vaudry, Mauro VallarinoAbstract:Among the extant Sarcopterygii, the interrelationship between the Dipnoi (lungfishes), Actinistia (coelacanths), and Tetrapoda (tetrapods) is controversial. Insulin has been purified from an extract of the pancreas of the African lungfishProtopterus annectensand its primary structure established as A-chain, Gly–Ile–Val–Glu–Gln–Cys–Cys–His–Lys–Pro10–Cys–Ser–Leu– Tyr –Glu–Leu–Glu–Asn–Tyr–Cys20–Asn–Val–Pro; and B-chain, Ala–Val–Leu–Asn–Gln–His–Leu–Cys–Gly–Ser10–His–Leu–Val– Glu– Ala–Leu–Tyr–Leu–Val–Cys20–Ala–Asp–Asn–Gly–Phe– Phe–Tyr–Lys–Pro–Ser30–Gly. Lungfish insulin contains unusual structural features, such as the dipeptide extension to the C-terminus of the A-chain and the substitution Arg → Asn at position B-23 in the putative receptor binding region of insulin, which may be expected to influence appreciably its biological potency relative to mammalian insulins. Lungfish insulin also contains amino acid substitutions such as Gly → Ala at position B-21, Glu → Asp at position B-22, and a Lys → Ser residue at position B-30, previously found in insulins from amphibia. This observation is consistent with paleontological data suggesting that lungfish and amphibia share a close phylogenetic relationship.
Douglas C. Woodhams - One of the best experts on this subject based on the ideXlab platform.
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the alyteserins two families of antimicrobial peptides from the skin secretions of the midwife toad alytes obstetricans alytidae
Peptides, 2009Co-Authors: Michael J Conlon, Anni Demandt, Per F. Nielsen, Hubert Vaudry, Jérôme Leprince, Douglas C. WoodhamsAbstract:Abstract Two families of structurally related C-terminally α-amidated antimicrobial peptides have been identified in norepinephrine-stimulated skin secretions of the midwife toad Alytes obstetricans (Alytidae). The alyteserin-1 peptides (Gly-Leu-Lys-(Asp/Glu)-Ile-Phe-Lys-Ala-Gly-Leu-Gly-Ser-Leu-Val-Lys-(Gly/Asn)-Ile-Ala-Ala-His-Val-Ala-(Asn/Ser).NH 2 ) show limited structural similarity to the ascaphins from the skins of frogs of the family Leiopelmatidae. Alyteserin-2a (Ile-Leu-Gly-Lys-Leu-Leu-Ser-Thr-Ala-Ala-Gly-Leu-Leu-Ser-Asn-Leu.NH 2 ) and alyteserin-2b and -2c (Ile-Leu-Gly-Ala-Ile-Leu-Pro-Leu-Val-Ser-Gly-Leu-Leu-Ser-(Asn/Ser)-Lys-Leu.NH 2 ) show limited sequence identity with bombinin H6, present in the skins of frogs of the family Bombinatoridae. The alyteserin-1 peptides show selective growth inhibitory activity against the Gram-negative bacteria Escherichia coli (MIC = 25 μM) whereas alyteserin-2a is more potent against the Gram-positive bacteria Staphylococcus aureus (MIC = 50 μM). The hemolytic activity against human erythrocytes of all peptides tested is relatively weak (LC 50 > 100 μM). The data demonstrate that the frogs belonging to the family Alytidae are among those producing dermal antimicrobial peptides that may represent a component of the animal's system of innate immunity.
