Biomedical subjects

K Soda

Publications and source records attributed to K Soda.

At least 181 records · Page 10Linked to original sources

PubMed1991

Mechanistic studies of two amino acid racemases of broad substrate specificity from Pseudomonas striata and Aeromonas caviae.

The conversion of L-[alpha-2H]alanine in H2O and unlabeled L-alanine in 2H2O into D-alanine, under nearly irreversible conditions, with the amino acid racemase from Pseudomonas striata showed significant internal transfer of the alpha-hydrogen. This result has been interpreted as being indicative of a single base mechanism for the racemization. The relative rates of deuterium incorporation into unlabeled D- and L-methionine by the two amino acid racemases of broad substrate specificity from P. striata and Aeromonas caviae, were measured in 2H2O. The results showed a markedly different pattern, dependent upon the configuration of the initial substrate; with D-methionine as substrate deuterium is incorporated into both enantiomers at approximately the same rate, but with L-methionine as substrate deuterium is incorporated considerably faster into the D than the L enantiomer. These results argue against a single base mechanism of racemization for these enzymes and are best rationalized in terms of a double base model where only one of the bases undergoes proton (deuterium) exchange with the solvent while the amino acid is enzyme-bound. The interpretation of the earlier experiment needs to be considered in light of these results.

Aeromonas↗

PubMed1991

Macrophage engulfment of mucosal mast cells in rats treated with dexamethasone.

The effects of corticosteroid treatment on mucosal mast cells in rat jejunal mucosa were examined. Rats previously infected with Nippostrongylus brasiliensis received a single IP injection of 1 mg dexamethasone. Three hours later, one third of mucosal mast cells demonstrated minor granular changes (fusion or peripheral clear zones) by electron microscopy. At 7 hours, by light microscopy, the majority of mucosal mast cells appeared abnormal with clustering of granules. By electron microscopy, 151 of 233 (65%) mucosal mast cells had been engulfed by enlarged macrophages and were in various stages of degeneration inside large phagosomes. By 24 hours, the number of mucosal mast cells had decreased to less than 10% of the initial number with parallel decreases in tissue rat mast cell protease II and histamine levels. Serum levels of rat mast cell protease II did not increase, and intestinal morphology was invariably normal with no evidence of inflammatory changes up to and including 24 hours. Observations were similar in uninfected animals. In contrast, in rats undergoing antigen-induced anaphylaxis, a significant elevation of serum rat mast cell protease II level was evident at 3 and 7 hours, and macrophage engulfment of mucosal mast cells was never seen, although tissue edema, enterocyte loss, and hemorrhage were observed. It is concluded that dexamethasone treatment results in macrophage engulfment and destruction of mucosal mast cells that occurs without granular mediator release and local inflammatory effects.

Animals↗

PubMed1991

Overproduction of glutamate racemase of Pediococcus pentosaceus in Escherichia coli clone cells and its purification.

We previously isolated a 6.0-kb DNA fragment that specifies glutamate racemase activity from the chromosomal DNA of Pediococcus pentosaceus by digestion with HindIII (N. Nakajima, K. Tanizawa, H. Tanaka, and K. Soda, 1986), Agric. Biol. Chem. 50, 2823-2830). We digested it further with EcoRI to obtain a fragment of 1.8 kb, which was blunt-ended and ligated into the SmaI site of vector plasmid pKK223-3. The recombinant plasmid showed a high glutamate racemase activity upon transformation of Escherichia coli W3110 cells with it; the plasmid was named pICR223. Glutamate racemase was overproduced in the clone cells and occurred in inclusion bodies in the cells. The enzyme was solubilized with 6 M urea, renatured by dialysis to remove urea, and purified to homogeneity with an overall yield of about 70% after a single DEAE-cellulose column chromatography. The amount of enzyme produced by the clone cells corresponded to about 38% of the total insoluble protein.

Amino Acid Isomerases↗

PubMed1991

Thermostable phenylalanine dehydrogenase of Thermoactinomyces intermedius: cloning, expression, and sequencing of its gene.

The gene encoding the thermostable phenylalanine dehydrogenase [EC 1.4.1.-] of a thermophile, Thermoactinomyces intermedius, was cloned and its complete DNA sequence was determined. The phenylalanine dehydrogenase gene (pdh) consists of 1,098 nucleotides and encodes 366 amino acid residues corresponding to the subunit (Mr 41,000) of the hexameric enzyme. The amino acid sequence deduced from the nucleotide sequence of the pdh gene of T. intermedius was 56.0 and 42.1% homologous to those of the phenylalanine dehydrogenases of Bacillus sphaericus and Sporosarcina ureae, respectively. It shows 47.5% homology to that of the thermostable leucine dehydrogenase from B. stearothermophilus. The pdh gene was highly expressed in E. coli JM109, the amount of phenylalanine dehydrogenase produced amounting up to about 8.3% of that of the total soluble protein. We purified the enzyme to homogeneity from transformant cells in a day, with a 58% recovery.

Actinomycetales↗

PubMed1991

Degradation of L-djenkolate catalyzed by S-alkylcysteine alpha,beta-lyase from Pseudomonas putida.

S-Alkylcysteine alpha, beta-lyase [EC 4.4.1.6] of Pseudomonas putida catalyzes alpha,beta-elimination of L-djenkolate [3,3'-methylenedithiobis(2-aminopropionic acid)] to produce pyruvate, ammonia, and S-(mercaptomethyl)cysteine initially. Secondly, S-(mercaptomethyl)-cysteine, which was identified in the form of S-(mercaptomethyl)cysteine thiolactone and S-(2-thia-3-carboxypropyl)cysteine in the absence and presence of iodoacetic acid, respectively, is decomposed enzymatically to pyruvate, ammonia, and bis(mercapto)methane, or spontaneously to cysteine, formaldehyde, and hydrogen sulfide. Balance studies showed that 1.3 mol each of pyruvate and ammonia and 0.2 mol each of formaldehyde and cysteine were produced with consumption of 1 mol of L-djenkolate. 1,2,4,5-Tetrathiane, 1,2,4-trithiolane, 1,2,4,6-tetrathiepane, and 1,2,3,5,6-pentathiepane, which are derivatives of bis(mercapto)methane, were also produced during the alpha,beta-elimination of L-djenkolate. In addition, a polymer with the general formula of -(CH2S)n- was produced as a white precipitate. When the alpha,beta-elimination of L-djenkolate was carried out in the presence of 20 mM iodoacetic acid, neither formaldehyde, cysteine, hydrogen sulfide, or the polymer were formed. Instead, the S-carboxymethyl derivatives of bis(mercapto)methane and S-(mercaptomethyl)cysteine were produced in addition to pyruvate and ammonia.

Biotransformation↗

PubMed1991

Thermostable alanine racemase of Bacillus stearothermophilus: subunit dissociation and unfolding.

The guanidine hydrochloride-induced subunit dissociation and unfolding of thermostable alanine racemase from Bacillus stearothermophilus have been studied by circular dichroism, fluorescence and absorption spectroscopies, and gel filtration. The overall process was found to be reversible: more than 75% of the original activity was recovered upon reduction of the denaturant concentration. In the range of 0.6 to 1.5 M guanidine hydrochloride, the dimeric enzyme was dissociated into a monomeric form, which was catalytically inactive. The monomeric enzyme appeared to bind the cofactor pyridoxal phosphate by a non-covalent linkage, although the native dimeric enzyme binds the cofactor through an aldimine Schiff base linkage. The monomer was mostly unfolded, with the transition occurring in the range of 1.8 to 2.2 M guanidine hydrochloride.

Alanine Racemase↗

PubMed1991

Purification and characterization of a new NAD(+)-dependent enzyme, L-tartrate decarboxylase, from Pseudomonas sp. group Ve-2.

A new enzyme, L-tartrate decarboxylase, was found in cells of Pseudomonas sp. group Ve-2. The enzyme was purified to homogeneity and characterized. The enzyme requires K+, Mg2+, and NAD+ for L-tartrate decarboxylation. The dependence of the enzymatic decarboxylation on NAD+ suggests that the decarboxylation involves redox reactions of the substrate. The enzyme catalyzes NAD(+)-linked oxidative decarboxylation of D-malate as well. The enzyme is composed of four subunits with identical molecular weight (Mr 40,000). The apparent Michaelis constants for L-tartrate and NAD+ are 1.1 mM, respectively. The cofactor requirements and the physical properties of the enzyme were similar to those of L-tartrate dehydrogenase-D-malate dehydrogenase from Rhodopseudomonas sphaeroides, and tartrate dehydrogenase from P. putida.

Carboxy-Lyases↗

PubMed1991

Distribution, purification, and characterization of thermostable phenylalanine dehydrogenase from thermophilic actinomycetes.

Phenylalanine dehydrogenase (L-phenylalanine:NAD oxidoreductase, deaminating; EC 1.4.1.-) was found in various thermophilic actinomycetes. We purified the enzyme to homogeneity from Thermoactinomyces intermedius IFO 14230 by heat treatment and by Red Sepharose 4B, DEAE-Toyopearl, Sepharose CL-4B, and Sephadex G-100 chromatographies with a 13% yield. The relative molecular weight of the native enzyme was estimated to be about 270,000 by gel filtration. The enzyme consists of six subunits identical in molecular weight (41,000) and is highly thermostable: it is not inactivated by incubation at pH 7.2 and 70 degrees C for at least 60 min or in the range of pH 5 to 10.8 at 50 degrees C for 10 min. The enzyme preferably acts on L-phenylalanine and its 2-oxo analog, phenylpyruvate, in the presence of NAD and NADH, respectively. Initial velocity and product inhibition studies showed that the oxidative deamination proceeds through a sequential ordered binary-ternary mechanism. The Km values for L-phenylalanine, NAD, phenylpyruvate, NADH, and ammonia were 0.22, 0.078, 0.045, 0.025, and 106 mM, respectively. The pro-S hydrogen at C-4 of the dihydronicotinamide ring of NADH was exclusively transferred to the substrate.

Actinomycetales↗

PubMed1991

Lowered responsiveness of bronchoalveolar lavage T lymphocytes in hypersensitivity pneumonitis.

We previously reported that Trichosporon cutaneum was the major causative antigen of summer-type hypersensitivity pneumonitis (HP) in Japan. In summer-type HP patients, we noticed that the proliferative responses of bronchoalveolar lavage (BAL) lymphocytes to phytohemagglutinin (PHA) and concanavalin A were significantly lower than those of the peripheral blood lymphocytes of the same patients. It was shown in this study that the low response of BAL lymphocytes was due to an intrinsic lowering of the responsiveness of the T cells. Results of the mixed culture experiments, in which the responses to mitogens of BAL and peripheral blood T cells mixed with either alveolar macrophages or blood monocytes were compared, indicated that the decreased proliferative response was due neither to the suppressive effect nor to defects in accessory function of the alveolar macrophages. BAL T cells did not act as suppressor cells when they were added to the culture of peripheral T cells. The decreased proliferative response was not due to the dominance of CD8+ T cells frequently seen in BAL cells of HP patients, because both CD4+ and CD8+ T cells separated from BAL cells of HP patients showed lower responsiveness than those of peripheral blood T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

[Systems analytical investigation of the effect of countermeasures against the AIDS epidemic among homosexuals].

In Japan, the AIDS (Acquired Immunodeficiency Syndrome) epidemic among haemophiliacs has been the most urgent issue, because of the large number of haemophiliacs with AIDS. However, after governmental approval of the production of heated coagulating agents in 1985 and 1986, the prime object of prevention against the AIDS epidemic shifted from transmission through coagulation agents to that through sexual contacts. In order to investigate the most appropriate countermeasures against the AIDS epidemic among homosexuals in Japan, the numbers of HIV (Human Immunodeficiency Virus)-infected cases and AIDS cases in the future were estimated, and changes of the future numbers of HIV-infected persons and AIDS cases by behavior of homosexuals were compared using a systems analytical method. The methods of estimation and comparison are similar to those of R. M. Anderson and others, using numerical analysis of a mathematical model consisting of differential equations. They assumed a closed homosexual group whose members seldom have contact with members of other homosexual groups, but we assumed an open homosexual group whose members are being infected by other groups, because this assumption was more appropriate to the situation of homosexual society in Japan. The results showed that the prevalence number of HIV-infected cases would be about 1,800, that the prevalence number of AIDS cases would be about 100 among 100,000 homosexuals at 20 years after the beginning of the AIDS epidemic, and that the most effective countermeasure was reducing the frequency of sexual contacts among members or taking prophylactic measures during sexual contacts. These prevalence numbers of HIV-infected cases and AIDS cases would be reduced to between 1/4 and 1/2 of the above-mentioned calculated values by promotion of that countermeasure.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Acyclic monoterpene primary alcohol:NADP+ oxidoreductase of Rauwolfia serpentina cells: the key enzyme in biosynthesis of monoterpene alcohols.

Acyclic monoterpene primary alcohol:NADP+ oxidoreductase, a key enzyme in the biosynthesis of monoterpene alcohols in plants, is unstable and has been only poorly characterized. However we have established conditions which stabilize the enzyme from Rauwolfia serpentina cells, and then purified it to homogeneity. It is a monomer with a molecular weight of about 44,000 and contains zinc ions. Various branched-chain allylic primary alcohols such as nerol, geraniol, and 10-hydroxygeraniol were substrates, but ethanol was inert. The enzyme exclusively requires NADP+ or NADPH as the cofactor. Steady-state kinetic studies showed that the nerol dehydrogenation proceeds by an ordered Bi-Bi mechanism. NADP+ binds the enzyme first and then NADPH is the second product released from it. Gas chromatography-mass spectrometric analysis of the reaction products showed that 10-hydroxygeraniol undergoes a reversible dehydrogenation to produce 10-oxogeraniol or 10-hydroxygeranial, which are oxidized further to give 10-oxogeranial, the direct precursor of iridodial. The enzyme has been found to exclusively transfer the pro-R hydrogen of NADPH to neral. The N-terminal sequence of the first 21 amino acids revealed no significant homology with those of various other proteins including the NAD(P)(+)-dependent alcohol dehydrogenases registered in a protein data bank.

Alcohol Oxidoreductases↗

PubMed1991

Characterization of the half and overall reactions catalyzed by L-lysine:2-oxoglutarate 6-aminotransferase.

Significant differences were found in the reaction rate, and the substrate and reaction specificities between the half reactions and the overall reactions catalyzed by L-lysine: 2-oxoglutarate 6-aminotransferase. The half reactions between an amino donor and the enzyme-bound pyridoxal 5'-phosphate, and also between an amino acceptor and the bound pyridoxamine 5'-phosphate followed first order reaction kinetics. The extrapolated first order rate constants and dissociation constants of the substrates were determined for the half reactions: lysine, 0.87 min-1 and 5.5 mM; glutamate, 1.1 min-1 and 10.5 mM; alanine, 0.66 min-1 and 6.6 mM; 6-aminohexanoate, 0.43 min-1 and 13.3 mM; and 2-oxoglutarate, 0.33 min-1 and 2.5 mM. As compared with the values reported for the overall reactions [Soda, K., Misono, H., & Yamamoto, T. (1968) Biochemistry 7, 4102-4109], the reactivity of the inherent substrates was lower by over 4 orders in the half reaction than that in the overall reaction, and the reactivity of alanine with the bound pyridoxal 5'-phosphate was reduced to 10% of that in the overall reaction. The substrate specificity in the half reaction was much lower than that in the overall reaction, which was re-examined in a reaction system containing the same concentration of the enzyme as that for the half reactions. Lysine 6-aminotransferase catalyzes the transfer of only the terminal amino group of lysine to 2-oxoglutarate in the overall reaction. However, in the half reaction, the 2-amino group as well as the terminal one was transferred to the bound pyridoxal 5'-phosphate. The ratio of reactivity of the 2-amino group to that of the 6-amino group was considerably influenced by the pH of the reaction mixture.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗

PubMed1991

The dynamics of intestinal eosinophil depletion in rats treated with dexamethasone.

We examined the effects of corticosteroid treatment on eosinophils in the jejunal mucosa of rats previously infected with Nippostrongylus brasiliensis. Rats received a single intraperitoneal injection of 1 mg of dexamethasone. At a light microscopic level, the number of eosinophils with typical nuclei and granules was significantly decreased as early as 3 hours after injection, and had diminished to 17% of starting values at 24 hours. Pyknotic cells containing eosinophilic granules or fragments were observed scattered in the subepithelial interstitial space 3 and 7 hours after injection. By electron microscopy, more than 20% of eosinophils demonstrated nuclear abnormalities. Degenerating eosinophils without granular changes (27 of 127, 14.1%) or with or with granular changes (9 of 127, 7.1%) increased at 3 hours compared with untreated rats (8 of 233, 3.4%; 4 of 233, 1.7%). At 7 hours, 47 of 96 (49.0%) eosinophils were located inside phagocytic vacuoles of macrophages. Single macrophages occasionally engulfed two or more eosinophils. Only a few degeneration eosinophils (7 of 96) were observed outside macrophages. At 13 hours, the percentage of degenerating eosinophils and eosinophils inside macrophages was decreased; at 24 hours, few eosinophils were seen and eosinophil structures could not be identified inside macrophages. The epithelium and lamina propria did not show structural damage typical of an inflammatory reaction at any time. Eosinophil numbers in mesenteric lymph nodes, spleens, and peripheral blood were also reduced by dexamethasone. Similar observations were made in the jejunal mucosa of noninfected rats. We observed the slow restoration of eosinophil numbers in the intestinal wall, finally reaching preinjection numbers after 14 days. We conclude that dexamethasone has important effects on eosinophils causing (a) nuclear degeneration and (b) changes in the granular matrix. Subsequently, these damaged eosinophils are engulfed by macrophages and swiftly disappear from the intestinal mucosa. These effects appear to be due to the induction of apoptosis. Our findings offer an explanation for one of the significant antiinflammatory effects observed with the use of corticosteroids.

Animals↗

PubMed1990

Substitution of glutamine for lysine at the pyridoxal phosphate binding site of bacterial D-amino acid transaminase. Effects of exogenous amines on the slow formation of intermediates.

In bacterial D-amino acid transaminase, Lys-145, which binds the coenzyme pyridoxal 5'-phosphate in Schiff base linkage, was changed to Gln-145 by site-directed mutagenesis (K145Q). The mutant enzyme had 0.015% the activity of the wild-type enzyme and was capable of forming a Schiff base with D-alanine; this external aldimine was formed over a period of minutes depending upon the D-alanine concentration. The transformation of the pyridoxal-5'-phosphate form of the enzyme to the pyridoxamine-5'-phosphate form (i.e. the half-reaction of transamination) occurred over a period of hours with this mutant enzyme. Thus, information on these two steps in the reaction and on the factors that influence them can readily be obtained with this mutant enzyme. In contrast, these reactions with the wild-type enzyme occur at much faster rates and are not easily studied separately. The mutant enzyme shows distinct preference for D- over L-alanine as substrates but it does so about 50-fold less effectively than the wild-type enzyme. Thus, Lys-145 probably acts in concert with the coenzyme and other functional side chain(s) to lead to efficient and stereochemically precise transamination in the wild-type enzyme. The addition of exogenous amines, ethanolamine or methyl amine, increased the rate of external aldimine formation with D-alanine and the mutant enzyme but the subsequent transformation to the pyridoxamine-5'-phosphate form of the enzyme was unaffected by exogenous amines. The wild-type enzyme displayed a large negative trough in the circular dichroic spectrum at 420 nm, which was practically absent in the mutant enzyme. However, addition of D-alanine to the mutant enzyme generated this negative Cotton effect (due to formation of the external aldimine with D-alanine). This circular dichroism band gradually collapsed in parallel with the transformation to the pyridoxamine-5'-phosphate enzyme. Further studies on this mutant enzyme, which displays the characteristics of the wild-type enzyme but at attenuated rates, may yield information on the factors controlling the stereochemistry of the reaction as well as on the catalytic steps of the transaminase pathway.

Base Sequence↗

PubMed1990

Thermostable alanine dehydrogenase from thermophilic Bacillus sphaericus DSM 462. Purification, characterization and kinetic mechanism.

Alanine dehydrogenase (L-alanine: NAD+ oxidoreductase, deaminating) was simply purified to homogeneity from a thermophile, Bacillus sphaericus DSM 462, by ammonium sulfate fractionation, red-Sepharose 4B chromatography and preparative slab gel electrophoresis. The enzyme had a molecular mass of about 230 kDa and consisted of six subunits with an identical molecular mass of 38 kDa. The enzyme was much more thermostable than that from a mesophile, B. sphaericus, and retained its full activity upon heating at 75 degrees C for at least 60 min and with incubation in pH 5.5-9.5 at 75 degrees C for 10 min. The enzyme can be stored without loss of its activity in a frozen state (-20 degrees C, at pH 7.2) for over 5 months. The optimum pH for the L-alanine deamination and pyruvate amination were around 10.5 and 8.2, respectively. The enzyme exclusively catalyzed the oxidative deamination of L-alanine in the presence of NAD+, but showed low amino acceptor specificity; hydroxypyruvate, oxaloacetate, 2-oxobutyrate and 3-fluoropyruvate are also aminated as well as pyruvate in the presence of NADH and ammonia. Initial velocity and product inhibition studies showed that the reductive amination proceeded through a sequential mechanism containing partially random binding. NADH binds first to the enzyme, and then pyruvate and ammonia bind in a random fashion. The products are sequentially released from the enzyme in the order L-alanine then NAD+. A dead-end inhibition by the formation of an abortive ternary complex which consists of the enzyme, NAD+ and pyruvate was included in the reaction. A possible role of the dead-end inhibition is to prevent the enzyme from functioning in the L-alanine synthesis. The Michaelis constants for the substrates were as follows: NADH, 0.10 mM; pyruvate, 0.50 mM; ammonia, 38.0 mM; L-alanine, 10.5 mM and NAD+, 0.26 mM.

Alanine Dehydrogenase↗

PubMed1990

Alanine dehydrogenases from two Bacillus species with distinct thermostabilities: molecular cloning, DNA and protein sequence determination, and structural comparison with other NAD(P)(+)-dependent dehydrogenases.

The gene encoding alanine dehydrogenase (EC 1.4.1.1) from a mesophile, Bacillus sphaericus, was cloned, and its complete DNA sequence was determined. In addition, the same gene from a moderate thermophile, B. stearothermophilus, was analyzed in a similar manner. Large parts of the two translated amino acid sequences were confirmed by automated Edman degradation of tryptic peptide fragments. Each alanine dehydrogenase gene consists of a 1116-bp open reading frame and encodes 372 amino acid residues corresponding to the subunit (Mr = 39,500-40,000) of the hexameric enzyme. The similarity of amino acid sequence between the two alanine dehydrogenases with distinct thermostabilities is very high (greater than 70%). The nonidentical residues are clustered in a few regions with relatively short length, which may correlate with the difference in thermal stability of the enzymes. Homology search of the primary structures of both alanine dehydrogenases with those of other pyridine nucleotide-dependent oxidoreductases revealed significant sequence similarity in the regions containing the coenzyme binding domain. Interestingly, several catalytically important residues in lactate and malate dehydrogenases are conserved in the primary structure of alanine dehydrogenases at matched positions with similar mutual distances.

Alanine Dehydrogenase↗

PubMed1990

Biochemistry and biotechnology of amino acid dehydrogenases.

Over the last decade, amino acid dehydrogenases such as alanine dehydrogenase (Ala DH), leucine dehydrogenase (Leu DH), and phenylalanine dehydrogenase (Phe DH) have been applied to the enantiomer-specific synthesis and analysis of various amino acids. In perticular, amino acid dehydrogenases from thermophiles have received much attention because of their high stability. Their productivity was enhanced and the purification facilitated by the gene cloning. The advances in biotechnological applications of these enzymes are based on fundamental studies concerning characteristics of the enzymes and reaction mechanism as described in this chapter. Further elucidation of the structure and function of these enzymes based on genetic engineering and protein engineering may enable their properties to be improved for their future uses in biotechnology.

Amino Acid Oxidoreductases↗

PubMed1990

Stereospecific abstraction of epsilon-pro-R-hydrogen of L-lysine by L-lysine epsilon-dehydrogenase from Agrobacterium tumefaciens.

The stereochemical aspects of the L-lysine epsilon-dehydrogenase reaction were examined with (6R)-L-[6-3H]lysine and (6S)-DL-[6-3H]lysine. When (6S)-DL-[6-3H]lysine was used as a substrate, the tritium was found in the product, delta 1-piperideine-6-carboxylate. In contrast, the radioactivity from (6R)-L-[6-3H]lysine was not retained in the product. Thus, the pro-R hydrogen at the prochiral C-6 carbon of L-lysine is specifically abstracted by the enzyme: the enzyme behaves stereochemically as an amino acid D-dehydrogenase.

Amino Acid Oxidoreductases↗