The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Fidel Toldrá - One of the best experts on this subject based on the ideXlab platform.
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contribution of muscle Aminopeptidases to flavor development in dry cured ham
Food Research International, 2000Co-Authors: Fidel Toldrá, M-concepción Aristoy, Mónica FloresAbstract:Abstract The activity of muscle Aminopeptidases (alanyl, arginyl, leucyl and pyroglutamyl Aminopeptidases) have been assayed along the processing of dry-cured ham. The generation of free amino acids resulting from aminopeptidase action on N-terminal of proteins and peptides has been also analyzed. The assayed Aminopeptidases, except pyroglutamyl aminopeptidase, showed good stability. Alanyl and arginyl Aminopeptidases have optimal neutral pH near the pH in ham and, in addition, their spectrum of activity against terminal amino acids is in coincidence with the observed release of free amino acids in ham. So, both Aminopeptidases appear to be the main contributors to the generation of free amino acids during the processing of dry-cured ham.
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EFFECT OF CARNOSINE, ANSERINE AND OTHER ENDOGENOUS SKELETAL PEPTIDES ON THE ACTIVITY OF PORCINE MUSCLE ALANYL AND ARGINYL Aminopeptidases
Journal of Food Biochemistry, 2000Co-Authors: Ma Pia Gianelli, Mónica Flores, V-javier Moya, M-concepción Aristoy, Fidel ToldráAbstract:The effect of endogenous dipeptides (carnosine and anserine) and peptidic fractions from meat extracts on aminopeptidase activity, alanyl and arginyl Aminopeptidases purified from porcine skeletal muscle, was studied. Carnosine inhibited the activity of porcine arginyl aminopeptidase (RAP); the inhibition being stronger with the purified form of the enzyme than in the muscle extract. The RAP inhibition was competitive. One of the peptidic fractions isolated from meat extracts inhibited RAP activity But the degree of inhibition depended on the extent of purification. The major aminopeptidase present in muscle, alanyl aminopeptidase (AAP), was neither inhibited by natural dipeptides nor arty of the peptidic fractions. The study of meat inhibitory peptides provides a better understanding of the action of proteolytic enzymes during meat processing.
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feedback inhibition of porcine muscle alanyl and arginyl Aminopeptidases in cured meat products
Journal of Agricultural and Food Chemistry, 1998Co-Authors: Mónica Flores, And Concepcion M Aristoy, Fidel ToldráAbstract:Alanyl and arginyl Aminopeptidases from porcine skeletal muscle were purified, and the effect of free amino acids on their activities was studied. Both Aminopeptidases were inhibited by free amino acids via the competitive mode and were more strongly inhibited in the pure form than when they were in the meat extract. Arginyl aminopeptidase (RAP)was less susceptible to inhibition by free amino acids than alanyl aminopeptidase (AAP), as shown especially by the strong inhibitory effect of hydrophobic amino acids on AAP activity in the meat extract. The free amino acid concentration present in meat products such as dry-cured loin and dry-cured ham produced a strong inhibitory effect on AAP and RAP activity. The concentration of free amino acids in cooked ham mainly affected the activity of AAP. These facts can explain the differences obtained in free amino acid concentration depending on the kind of process or product. Keywords: Aminopeptidase; muscle exopeptidases; peptidase inhibitor; amino acid
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myoglobin as an inhibitor of exopeptidases from lactobacillus sake
Applied and Environmental Microbiology, 1998Co-Authors: Yolanda Sanz, Fidel ToldráAbstract:The effects of myoglobin on exopeptidases of Lactobacillus sake were determined. Inhibition of the Aminopeptidases increased as the myoglobin concentration increased; aminopeptidase 3 was the most affected (90% inhibition). Aminopeptidases 1, 2, and 4 showed similar inhibition levels (around 60%). Myoglobin did not affect tripeptidase activity. Thus, myoglobin could limit amino acid generation in meat systems.
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Curing agents affect aminopeptidase activity from porcine skeletal muscle
Zeitschrift f�r Lebensmitteluntersuchung und -Forschung A, 1997Co-Authors: Mónica Flores, M-concepción Aristoy, Fidel ToldráAbstract:The effect of curing agents (salt, nitrite, nitrate, ascorbic acid, glucose and polyphosphates) on the main pure Aminopeptidases involved in the release of amino acids during the processing of cured meat products has been studied. Salt strongly inhibited alanyl aminopeptidase and pyroglutamyl aminopeptidase: about 40–50% of their original activities were recovered in the presence of 4–5% salt, the typical concentration in dry-cured meat products, while leucyl aminopeptidase was not affected. However, arginyl aminopeptidase was activated to 2–3 times its control level. Nitrate and nitrite did not affect aminopeptidase activity. Ascorbic acid (500 mg/l) slightly inhibited arginyl, alanyl and pyroglutamyl Aminopeptidases whereas glucose (20 g/l) activated (to almost 5 times its control level) leucyl aminopeptidase activity. Polyphosphates inhibited (25%) alanyl and arginyl Aminopeptidases.
Takashi Izumi - One of the best experts on this subject based on the ideXlab platform.
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Leukotriene A4 hydrolase, a bifunctional enzyme Distinction of leukotriene A4 hydrolase and aminopeptidase activities by site‐directed mutagenesis at Glu‐297
FEBS Letters, 1992Co-Authors: Michiko Minami, Nobuya Ohishi, Masashi Miyano, Hiroyuki Mutoh, Shinobu Shimada, Mikiro Mori, Hideaki Tsuge, Haruhiko Bito, Hiroo Wada, Takashi IzumiAbstract:We previously obtained evidence for intrinsic aminopeptidase activity for leukotriene (LT)A4 hydrolase, an enzyme characterized to specifically catalyse the hydrolysis of LTA4 to LTB4, a chemotactic compound. From a sequence homology search between LTA4 hydrolase and several Aminopeptidases, it became clear that they share a putative active site for known Aminopeptidases and a zinc binding domain. Thus, Glu-297 of LTA4 hydrolase is a candidate for the active site of its aminopeptidase activity, while His-296, His-300 and Glu-319 appear to constitute a zinc binding site. To determine whether or not this putative active site is also essential to LTA4 hydrolase activity, site-directed mutagenesis experiments were carried out. Glu-297 was mutated into 4 different amino acids. The mutant E297Q (Glu changed to Gln) conserved LTA4 hydrolase activity but showed little aminopeptidase activity. Other mutants at Glu-297 (E297A, E297D and E297K) showed markedly reduced amounts of both activities. It is thus proposed that either a glutamic or glutamine moiety at 297 is required for full LTA4 hydrolase activity, while the free carboxylic acid of glutamic acid is essential for aminopeptidase.
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leukotriene a4 hydrolase a bifunctional enzyme distinction of leukotriene a4 hydrolase and aminopeptidase activities by site directed mutagenesis at glu 297
FEBS Letters, 1992Co-Authors: Michiko Minami, Nobuya Ohishi, Masashi Miyano, Hiroyuki Mutoh, Shinobu Shimada, Mikiro Mori, Hideaki Tsuge, Haruhiko Bito, Hiroo Wada, Takashi IzumiAbstract:We previously obtained evidence for intrinsic aminopeptidase activity for leukotriene (LT)A4 hydrolase, an enzyme characterized to specifically catalyse the hydrolysis of LTA4 to LTB4, a chemotactic compound. From a sequence homology search between LTA4 hydrolase and several Aminopeptidases, it became clear that they share a putative active site for known Aminopeptidases and a zinc binding domain. Thus, Glu-297 of LTA4 hydrolase is a candidate for the active site of its aminopeptidase activity, while His-296, His-300 and Glu-319 appear to constitute a zinc binding site. To determine whether or not this putative active site is also essential to LTA4 hydrolase activity, site-directed mutagenesis experiments were carried out. Glu-297 was mutated into 4 different amino acids. The mutant E297Q (Glu changed to Gln) conserved LTA4 hydrolase activity but showed little aminopeptidase activity. Other mutants at Glu-297 (E297A, E297D and E297K) showed markedly reduced amounts of both activities. It is thus proposed that either a glutamic or glutamine moiety at 297 is required for full LTA4 hydrolase activity, while the free carboxylic acid of glutamic acid is essential for aminopeptidase.
Mónica Flores - One of the best experts on this subject based on the ideXlab platform.
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contribution of muscle Aminopeptidases to flavor development in dry cured ham
Food Research International, 2000Co-Authors: Fidel Toldrá, M-concepción Aristoy, Mónica FloresAbstract:Abstract The activity of muscle Aminopeptidases (alanyl, arginyl, leucyl and pyroglutamyl Aminopeptidases) have been assayed along the processing of dry-cured ham. The generation of free amino acids resulting from aminopeptidase action on N-terminal of proteins and peptides has been also analyzed. The assayed Aminopeptidases, except pyroglutamyl aminopeptidase, showed good stability. Alanyl and arginyl Aminopeptidases have optimal neutral pH near the pH in ham and, in addition, their spectrum of activity against terminal amino acids is in coincidence with the observed release of free amino acids in ham. So, both Aminopeptidases appear to be the main contributors to the generation of free amino acids during the processing of dry-cured ham.
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EFFECT OF CARNOSINE, ANSERINE AND OTHER ENDOGENOUS SKELETAL PEPTIDES ON THE ACTIVITY OF PORCINE MUSCLE ALANYL AND ARGINYL Aminopeptidases
Journal of Food Biochemistry, 2000Co-Authors: Ma Pia Gianelli, Mónica Flores, V-javier Moya, M-concepción Aristoy, Fidel ToldráAbstract:The effect of endogenous dipeptides (carnosine and anserine) and peptidic fractions from meat extracts on aminopeptidase activity, alanyl and arginyl Aminopeptidases purified from porcine skeletal muscle, was studied. Carnosine inhibited the activity of porcine arginyl aminopeptidase (RAP); the inhibition being stronger with the purified form of the enzyme than in the muscle extract. The RAP inhibition was competitive. One of the peptidic fractions isolated from meat extracts inhibited RAP activity But the degree of inhibition depended on the extent of purification. The major aminopeptidase present in muscle, alanyl aminopeptidase (AAP), was neither inhibited by natural dipeptides nor arty of the peptidic fractions. The study of meat inhibitory peptides provides a better understanding of the action of proteolytic enzymes during meat processing.
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feedback inhibition of porcine muscle alanyl and arginyl Aminopeptidases in cured meat products
Journal of Agricultural and Food Chemistry, 1998Co-Authors: Mónica Flores, And Concepcion M Aristoy, Fidel ToldráAbstract:Alanyl and arginyl Aminopeptidases from porcine skeletal muscle were purified, and the effect of free amino acids on their activities was studied. Both Aminopeptidases were inhibited by free amino acids via the competitive mode and were more strongly inhibited in the pure form than when they were in the meat extract. Arginyl aminopeptidase (RAP)was less susceptible to inhibition by free amino acids than alanyl aminopeptidase (AAP), as shown especially by the strong inhibitory effect of hydrophobic amino acids on AAP activity in the meat extract. The free amino acid concentration present in meat products such as dry-cured loin and dry-cured ham produced a strong inhibitory effect on AAP and RAP activity. The concentration of free amino acids in cooked ham mainly affected the activity of AAP. These facts can explain the differences obtained in free amino acid concentration depending on the kind of process or product. Keywords: Aminopeptidase; muscle exopeptidases; peptidase inhibitor; amino acid
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Curing agents affect aminopeptidase activity from porcine skeletal muscle
Zeitschrift f�r Lebensmitteluntersuchung und -Forschung A, 1997Co-Authors: Mónica Flores, M-concepción Aristoy, Fidel ToldráAbstract:The effect of curing agents (salt, nitrite, nitrate, ascorbic acid, glucose and polyphosphates) on the main pure Aminopeptidases involved in the release of amino acids during the processing of cured meat products has been studied. Salt strongly inhibited alanyl aminopeptidase and pyroglutamyl aminopeptidase: about 40–50% of their original activities were recovered in the presence of 4–5% salt, the typical concentration in dry-cured meat products, while leucyl aminopeptidase was not affected. However, arginyl aminopeptidase was activated to 2–3 times its control level. Nitrate and nitrite did not affect aminopeptidase activity. Ascorbic acid (500 mg/l) slightly inhibited arginyl, alanyl and pyroglutamyl Aminopeptidases whereas glucose (20 g/l) activated (to almost 5 times its control level) leucyl aminopeptidase activity. Polyphosphates inhibited (25%) alanyl and arginyl Aminopeptidases.
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Biogenic Polyamines Affect Activity of Aminopeptidase B and Alanyl Aminopeptidase from Porcine Skeletal Muscle
Journal of Food Science, 1996Co-Authors: Mónica Flores, M-concepción Aristoy, Fidel ToldráAbstract:The effect of biogenic polyamines (agmatine, cadaverine, putrescine, spermidine, and spermine) on the activity of pork muscle aminopeptidase and alanyl aminopeptidase was investigated. Agmatine (5 mM) showed a powerful inhibitory effect for both enzymes (more than 50% inhibition). Cadaverine and less intensely putrescine showed similar inhibitory effects for both enzymes. All assayed polyamines inhibited activity of both Aminopeptidases except spermine and spermidine which did not affect aminopeptidase B. Thus, one of these inhibitors could be used to avoid the interference of alanyl aminopeptidase when assaying aminopeptidase B in muscle extracts.
Andrew D. Steen - One of the best experts on this subject based on the ideXlab platform.
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Potential Activities of Freshwater Exo- and Endo-Acting Extracellular Peptidases in East Tennessee and the Pocono Mountains.
Frontiers in Microbiology, 2018Co-Authors: Lauren Mullen, Kim Boerrigter, Nicholas Ferriero, Jeff Rosalsky, Abigail Van Buren Barrett, Patrick James Murray, Andrew D. SteenAbstract:Proteins constitute a particularly bioavailable subset of organic carbon and nitrogen in aquatic environments but must be hydrolyzed by extracellular enzymes prior to being metabolized by microorganisms. Activities of extracellular peptidases (protein-degrading enzymes) have frequently been assayed in freshwater systems, but such studies have been limited to substrates for a single enzyme (leucyl aminopeptidase) out of more than 300 biochemically-recognized peptidases. Here we report kinetic measurements of extracellular hydrolysis of five substrates in twenty-eight freshwater bodies in the Delaware Water Gap National Recreation Area in the Pocono Mountains (Pennsylvania, USA) and near Knoxville, Tennessee (USA), between 2013 and 2016. The assays putatively test for four Aminopeptidases (arginyl aminopeptidase, glyclyl aminopeptidase, leucyl aminopeptidase and pyroglutamyl aminopeptidase), which cleave N-terminal amino acids from proteins, and trypsin, an endopeptidase, which cleaves proteins mid-chain. Aminopeptidase and the trypsin-like activity were observed in all water bodies, indicating that a diverse set of peptidases is typical in fresh water. However, ratios of peptidase activities were variable among sites: Aminopeptidases dominated at some sites, trypsin-like activity at others. At a given site the ratios remained fairly consistent over time, indicating that they are driven by ecological factors. Studies in which only leucyl aminopeptidase activity is measured may underestimate the total peptidolytic capacity of an environment, due to the variable contribution of endopeptidases.
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2018Co-Authors: Lauren Mullen, Kim Boerrigter, Nicholas Ferriero, Jeff Rosalsky, Abigail Van Buren Barrett, Patrick James Murray, Malcolm Shabazz High School Aquatic Biogeochemistry X Team, Andrew D. SteenAbstract:Proteins constitute a particularly bioavailable subset of organic carbon and nitrogen in aquatic environments but must be hydrolyzed by extracellular enzymes prior to being metabolized by microorganisms. Activities of extracellular peptidases (protein-degrading enzymes) have frequently been assayed in freshwater systems, but such studies have been limited to substrates for a single enzyme [leucyl aminopeptidase (Leu-AP)] out of more than 300 biochemically recognized peptidases. Here, we report kinetic measurements of extracellular hydrolysis of five substrates in 28 freshwater bodies in the Delaware Water Gap National Recreation Area in the Pocono Mountains (PA, United States) and near Knoxville (TN, United States), between 2013 and 2016. The assays putatively test for four Aminopeptidases (arginyl aminopeptidase, glyclyl aminopeptidase, Leu-AP, and pyroglutamyl aminopeptidase), which cleave N-terminal amino acids from proteins, and trypsin, an endopeptidase, which cleaves proteins mid-chain. Aminopeptidase and the trypsin-like activity were observed in all water bodies, indicating that a diverse set of peptidases is typical in freshwater. However, ratios of peptidase activities were variable among sites: Aminopeptidases dominated at some sites and trypsin-like activity at others. At a given site, the ratios remained fairly consistent over time, indicating that they are driven by ecological factors. Studies in which only Leu-AP activity is measured may underestimate the total peptidolytic capacity of an environment, due to the variable contribution of endopeptidases.
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2018Co-Authors: Lauren Mullen, Kim Boerrigter, Nicholas Ferriero, Jeff Rosalsky, Abigail Van Buren Barrett, Patrick James Murray, Malcolm Shabazz High School Aquatic Biogeochemistry X Team, Andrew D. SteenAbstract:Proteins constitute a particularly bioavailable subset of organic carbon and nitrogen in aquatic environments but must be hydrolyzed by extracellular enzymes prior to being metabolized by microorganisms. Activities of extracellular peptidases (protein-degrading enzymes) have frequently been assayed in freshwater systems, but such studies have been limited to substrates for a single enzyme [leucyl aminopeptidase (Leu-AP)] out of more than 300 biochemically recognized peptidases. Here, we report kinetic measurements of extracellular hydrolysis of five substrates in 28 freshwater bodies in the Delaware Water Gap National Recreation Area in the Pocono Mountains (PA, United States) and near Knoxville (TN, United States), between 2013 and 2016. The assays putatively test for four Aminopeptidases (arginyl aminopeptidase, glyclyl aminopeptidase, Leu-AP, and pyroglutamyl aminopeptidase), which cleave N-terminal amino acids from proteins, and trypsin, an endopeptidase, which cleaves proteins mid-chain. Aminopeptidase and the trypsin-like activity were observed in all water bodies, indicating that a diverse set of peptidases is typical in freshwater. However, ratios of peptidase activities were variable among sites: Aminopeptidases dominated at some sites and trypsin-like activity at others. At a given site, the ratios remained fairly consistent over time, indicating that they are driven by ecological factors. Studies in which only Leu-AP activity is measured may underestimate the total peptidolytic capacity of an environment, due to the variable contribution of endopeptidases.
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Potential Activities of Freshwater Exo- and Endo-Acting Extracellular Peptidases in East Tennessee and the Pocono Mountains
Frontiers Media S.A., 2018Co-Authors: Lauren Mullen, Kim Boerrigter, Nicholas Ferriero, Jeff Rosalsky, Abigail Van Buren Barrett, Patrick James Murray, Malcolm Shabazz High School Aquatic Biogeochemistry X Team, Andrew D. SteenAbstract:Proteins constitute a particularly bioavailable subset of organic carbon and nitrogen in aquatic environments but must be hydrolyzed by extracellular enzymes prior to being metabolized by microorganisms. Activities of extracellular peptidases (protein-degrading enzymes) have frequently been assayed in freshwater systems, but such studies have been limited to substrates for a single enzyme [leucyl aminopeptidase (Leu-AP)] out of more than 300 biochemically recognized peptidases. Here, we report kinetic measurements of extracellular hydrolysis of five substrates in 28 freshwater bodies in the Delaware Water Gap National Recreation Area in the Pocono Mountains (PA, United States) and near Knoxville (TN, United States), between 2013 and 2016. The assays putatively test for four Aminopeptidases (arginyl aminopeptidase, glyclyl aminopeptidase, Leu-AP, and pyroglutamyl aminopeptidase), which cleave N-terminal amino acids from proteins, and trypsin, an endopeptidase, which cleaves proteins mid-chain. Aminopeptidase and the trypsin-like activity were observed in all water bodies, indicating that a diverse set of peptidases is typical in freshwater. However, ratios of peptidase activities were variable among sites: Aminopeptidases dominated at some sites and trypsin-like activity at others. At a given site, the ratios remained fairly consistent over time, indicating that they are driven by ecological factors. Studies in which only Leu-AP activity is measured may underestimate the total peptidolytic capacity of an environment, due to the variable contribution of endopeptidases
Michiko Minami - One of the best experts on this subject based on the ideXlab platform.
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Leukotriene A4 hydrolase, a bifunctional enzyme Distinction of leukotriene A4 hydrolase and aminopeptidase activities by site‐directed mutagenesis at Glu‐297
FEBS Letters, 1992Co-Authors: Michiko Minami, Nobuya Ohishi, Masashi Miyano, Hiroyuki Mutoh, Shinobu Shimada, Mikiro Mori, Hideaki Tsuge, Haruhiko Bito, Hiroo Wada, Takashi IzumiAbstract:We previously obtained evidence for intrinsic aminopeptidase activity for leukotriene (LT)A4 hydrolase, an enzyme characterized to specifically catalyse the hydrolysis of LTA4 to LTB4, a chemotactic compound. From a sequence homology search between LTA4 hydrolase and several Aminopeptidases, it became clear that they share a putative active site for known Aminopeptidases and a zinc binding domain. Thus, Glu-297 of LTA4 hydrolase is a candidate for the active site of its aminopeptidase activity, while His-296, His-300 and Glu-319 appear to constitute a zinc binding site. To determine whether or not this putative active site is also essential to LTA4 hydrolase activity, site-directed mutagenesis experiments were carried out. Glu-297 was mutated into 4 different amino acids. The mutant E297Q (Glu changed to Gln) conserved LTA4 hydrolase activity but showed little aminopeptidase activity. Other mutants at Glu-297 (E297A, E297D and E297K) showed markedly reduced amounts of both activities. It is thus proposed that either a glutamic or glutamine moiety at 297 is required for full LTA4 hydrolase activity, while the free carboxylic acid of glutamic acid is essential for aminopeptidase.
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leukotriene a4 hydrolase a bifunctional enzyme distinction of leukotriene a4 hydrolase and aminopeptidase activities by site directed mutagenesis at glu 297
FEBS Letters, 1992Co-Authors: Michiko Minami, Nobuya Ohishi, Masashi Miyano, Hiroyuki Mutoh, Shinobu Shimada, Mikiro Mori, Hideaki Tsuge, Haruhiko Bito, Hiroo Wada, Takashi IzumiAbstract:We previously obtained evidence for intrinsic aminopeptidase activity for leukotriene (LT)A4 hydrolase, an enzyme characterized to specifically catalyse the hydrolysis of LTA4 to LTB4, a chemotactic compound. From a sequence homology search between LTA4 hydrolase and several Aminopeptidases, it became clear that they share a putative active site for known Aminopeptidases and a zinc binding domain. Thus, Glu-297 of LTA4 hydrolase is a candidate for the active site of its aminopeptidase activity, while His-296, His-300 and Glu-319 appear to constitute a zinc binding site. To determine whether or not this putative active site is also essential to LTA4 hydrolase activity, site-directed mutagenesis experiments were carried out. Glu-297 was mutated into 4 different amino acids. The mutant E297Q (Glu changed to Gln) conserved LTA4 hydrolase activity but showed little aminopeptidase activity. Other mutants at Glu-297 (E297A, E297D and E297K) showed markedly reduced amounts of both activities. It is thus proposed that either a glutamic or glutamine moiety at 297 is required for full LTA4 hydrolase activity, while the free carboxylic acid of glutamic acid is essential for aminopeptidase.