The 160 N-terminal residues of calnexin define a novel region supporting viability in Schizosaccharomyces pombe

Protein secretion is a complex process that can be modulated by folding factors in the endoplasmic reticulum (ER), such as calnexin, a highly-conserved molecular chaperone involved in quality control. In Schizosaccharomyces pombe, calnexin (Cnx1p) is essential for cell viability. The calnexin/Cnx1p determinants required for viability have been mapped within the last 123 residues of its C-terminus. To better understand the role(s) of calnexin/Cnx1p in secretion, we screened for cnx1 mutants 'super-secreting' cellulase. We identified ss14_cnx1, a mutant secreting 10-fold higher levels of the glycoprotein cellulase than the wild-type strain. While cellulase did not interact with ss14_Cnx1p, the ratio of secreted activity/quantity for this enzyme was not affected, suggesting that the quality control of folding in the ER was adequate in the mutant strain. Surprisingly, the ss14_Cnx1p mutant is composed of the 160 N-terminal amino acids of the mature molecule, thus this mutant defines a novel calnexin/Cnx1p region supporting Sz. pombe viability. Interestingly, like viable mutants spanning the last 52 aa of calnexin/Cnx1p, the 160 N-terminal residues encoded by ss14_cnx1 also forms a complex with the essential BiP chaperone. These results reveal the so far unidentified importance of the N-terminal region of calnexin/Cnx1p.     

Posttranslational activation, site-directed mutation and phylogenetic analyses of the lysine biosynthesis enzymes alpha-aminoadipate reductase Lys1p (AAR) and the phosphopantetheinyl transferase Lys7p (PPTase) from Schizosaccharomyces pombe

Alpha-aminoadipate reductase (AAR), the signature enzyme for lysine biosynthesis in fungi, catalyses the conversion of alpha-aminoadipate to alpha-aminoadipate-semiadehyde in the presence of ATP and NADPH. In Saccharomyces cerevisiae and Candida albicans, the LYS2-encoded AAR is posttranslationally activated by CoA and the LYS5-encoded PPTase. The fission yeast Schizosaccharomyces pombe is evolutionarily highly diverged from S. cerevisiae and C. albicans. We report here several unusual activation characteristics of Sz. pombe Lys1p and Lys7p, isofunctional to Lys2p (AAR) and Lys5p (PPTase), respectively. Unlike the Lys2p from S. cerevisiae and C. albicans, the Sz. pombe Lys1p was active when expressed in E. coli and exhibited significant AAR activity without the addition of CoA or the Sz. pombe Lys7p intron free PPTase. Somewhat higher AAR activity was obtained with the addition of CoA and the Sz. pombe Lys7p PPTase. Substitution of G910A, S913T or S913A in the Sz. pombe Lys1p activation domain (IGGHSI) resulted in no AAR activity. Similarly, substitutions of several amino acid residues in the Sz. pombe Lys7p PPTase domain (G79A, R80K and P81A in Core 1; F93W, D94E, F95W and N96D in Core 1a; G124A, V125I and D126E in Core 2; K172R, E173D and K177R in Core 3) also resulted in no activation of Lys1p and no AAR activity. The Sz. pombe Lys1p amino acid sequence showed a high degree of similarity to other fungal Lys2p proteins; however, the Lys7p amino acid sequence showed much less similarity to other bacterial, fungal and animal PPTases representing several phylogenetic groups.     

Aspergillus ficuum菊粉酶的化学修饰

应用NBS、DEPC、EDC、DIC、Ch-T、PMSF 和DTT 化学修饰剂对Aspergillus ficuum 产内切菊粉酶和外切菊粉酶进行化学修饰,测定与其活性相关的氨基酸残基,结果表明,构成内切菊粉酶和外切菊粉酶活性中心的必需氨基酸残基均含有色氨酸和羧基氨基酸(谷氮酸或天门冬氨酸),组氨酸可能是酶活性中心的组成氨基酸。邹氏作图法进一步确认外切菊粉酶活性中心必需色氨酸残基数目为2,内切菊粉酶活性中心必需色氨酸残基数目为1 。     

Expression,purification, and characterization of N-acetylglucosaminylphosphatidylinositol de-N-acetylase (ScGpi12), the enzyme that catalyses the second step of GPI biosynthesis in S. cerevisiae

ScGpi12 is a 304 amino residue long endoplasmic reticulum membrane protein, which participates in the de-N-acetylation of N-acetylglucosaminyl phosphatidylinositol to produce glucosaminyl phosphatidylinositol in the second step of GPI anchor biosynthesis pathway in Saccharomyces cerevisiae. ScGpi12 was cloned in a pMAL-c2x vector and expressed heterologously in Rosetta-gami (DE3) strain of E. coli. Affinity purification of the protein yielded low amounts of the MBP-tagged enzyme, which was active. To the best of our knowledge, this is the first successful purification of full-length Gpi12 enzyme, without the accompanying GroEL that was seen in other studies. The presence of the tag did not greatly alter the activity of the enzyme. ScGpi12 was optimally active in the pH range of 6.5–8.5 and at 30 °C. It was not sensitive to treatment with EDTA but was stimulated by multiple divalent cations. The divalent cation did not alter the pH profile of the enzyme, suggesting no role of the divalent metal in creating a nucleophile for catalysis. Divalent cations did, however, enhance the turnover number of the enzyme for its substrate, suggesting that they are probably required for the production of a catalytically competent active site by bringing the active site residues within optimum distance of the substrate for catalysis.     

The structure and function of Saccharomyces cerevisiae proteinase A

Saccharomyces cerevisiae proteinase A (saccharopepsin; EC 3.4.23.25) is a member of the aspartic proteinase superfamily (InterPro IPR001969), which are proteolytic enzymes distributed among a variety of organisms. Targeted to the vacuole as a zymogen, its activation at acidic pH can occur by two different pathways, a one-step process to release mature proteinase A, involving the intervention of proteinase B, or a step-wise pathway via the autoactivation product known as pseudo-proteinase A. Once active, S. cerevisiae proteinase A is essential to the activities of other yeast vacuolar hydrolases, including proteinase B and carboxypeptidase Y. The mature enzyme is bilobal, with each lobe providing one of the two catalytically essential aspartic acid residues in the active site. The crystal structure of free proteinase A reveals that the flap loop assumes an atypical position, pointing directly into the S(1) pocket of the enzyme. With regard to hydrolysis, proteinase A has a preference for hydrophobic residues with Phe, Leu or Glu at the P1 position and Phe, Ile, Leu or Ala at P1', and is inhibited by IA(3), a natural and highly specific inhibitor produced by S. cerevisiae. This review is the first comprehensive review of S. cerevisiae PrA.     

利巴韦林抗酪氨酸酶活性及其在贡梨中的保鲜应用

酪氨酸酶是果蔬褐变和黑色素生物合成过程中的关键酶,酪氨酸酶抑制剂在果蔬保鲜和医药领域具有重要意义。该文首次研究了利巴韦林的抗酪氨酸酶活性、机制及其对贡梨鲜切梨块和梨汁的保鲜效果。酶动力学实验的结果表明,利巴韦林是高效、可逆、竞争型的酪氨酸酶抑制剂,其IC₅₀为(0.3±0.05)mmol/L。荧光淬灭和非辐射能量转移实验的结果表明,利巴韦林可静态淬灭酪氨酸酶的内源荧光,且通过1个结合位点与酪氨酸酶形成“利巴韦林-酶”复合物并导致酶的构象发生改变,这一过程伴随着非辐射能量转移。分子对接的结果表明,利巴韦林可以嵌入到酪氨酸酶的活性口袋并与其B链上的6个氨基酸残基(Lys379、Gln356、Gln307、Asp312、Val313、Asn310)形成氢键。贡梨保鲜实验表明,利巴韦林可以有效减少鲜切梨块的失重率和降低梨汁的褐变度。该研究结果为开发新型的果蔬保鲜剂提供了理论依据和实践基础。     

Translational regulator RpL10p/Grc5p interacts physically and functionally with Sed1p,a dynamic component of the yeast cell surface

Biogenesis of an active ribosome complement and a dynamic cell surface complement are two major determinants of cellular growth. In yeast, the 60S ribosomal subunit protein RpL10p/Grc5p functions during successive stages in ribosome biogenesis, specifically rRNA processing, nucle(ol)ar preribosomal subunit assembly, nucleo-cytoplasmic transport and cytoplasmic maturation of ribosomes. Here, we report that a two-hybrid screen identified yeast genes SED1, ACS2 and PLB3 as encoding proteins physically interacting with both ribosomal RpL10p/Grc5p and its human homologue hRpL10p/QMp. SED1 encodes a differentially expressed cell wall protein which is proposed to be first transiently secreted to the plasma membrane as a GPI (glycosylated derivative of phosphoinositol)-anchored form and to be then transferred to the glucan layer of the cell wall. Ectopic expression of SED1 rescues both the aberrant growth phenotype and the translation defect of grc5-1(ts) temperature-sensitive cells. Furthermore, we report that Sed1p associates with translating ribosomes suggesting a novel, cytoplasmic role for Sed1p. ACS2 encodes one of the two yeast acetyl-CoA synthases and represents a key enzyme in one of several metabolic routes to produce acetyl-CoA, which in turn is indispensable for lipid biosynthesis. PLB3 encodes a phospholipase, which is active in the breakdown of membrane lipids. Our results support the view that Grc5p/RpL10p links ribosome function to membrane turnover and cell surface biogenesis.     

ARH1 of Saccharomyces cerevisiae: A new essential gene that codes for a protein homologous to the human adrenodoxin reductase

A yeast gene was found in which the derived protein sequence has similarity to human and bovine adrenodoxin reductase (Nobrega, F. G., Nobrega, M. P. and Tzagoloff, A. (1992). EMBO J. 11, 3821–3829; Lacour, T. and Dumas, B. (1996). Gene 174, 289–292), an enzyme in the mitochondrial electron transfer chain that catalyses in mammals the conversion of cholesterol into pregnenolone, the first step in the synthesis of all steroid hormones. It was named ARH1 (Adrenodoxin Reductase Homologue 1) and here we show that it is essential. Rescue was possible by the yeast gene, but failed with the human gene. Supplementation was tried without success with various sterols, ruling out its involvement in the biosynthesis of ergosterol. Immunodetection with a specific polyclonal antibody located the gene product in the mitochondrial fraction. Consequently ARH1p joins the small group of gene products that affect essential functions carried out by the organelle and not linked to oxidative phosphorylation. © 1998 John Wiley & Sons, Ltd.     

Disruption of the KEX1 gene in Pichia pastoris allows expression of full‐length murine and human endostatin

Endostatin is a potent angiogenesis inhibitor. In order to isolate sufficient quantities of soluble protein for in vivo studies in mice, we expressed murine endostatin in Pichia pastoris. Analysis of the expressed protein by mass spectrometry indicated that the protein was truncated. N‐terminal sequence analysis determined that the N‐terminus was intact, suggesting that the C‐terminal lysine was missing. In Saccharomyces cerevisiae, Kex1p can cleave lysine and arginine residues from the C‐terminus of peptides and proteins. We hypothesized that the KEX1 homologue in P. pastoris is responsible for the loss of the C‐terminal lysine of endostatin. To test this hypothesis, we cloned and disrupted the P. pastoris KEX1 gene. Although the overall amino acid identity between the P. pastoris and the S. cerevisae Kex1p is only 36%, the amino acid residues involved in the catalytic activity or close to the active residues are highly conserved. Disruption of the KEX1 reading frame allowed expression of murine and human endostatin with the C‐terminal lysine. The KEX1 disruption strain may be a useful tool for the expression of other proteins with a C‐terminal basic amino acid. Addition of a lysine to the C‐terminus of recombinant proteins may protect the C‐terminus from degradation by other carboxypeptidases. 3·5 kb of the P. pastoris KEX1 gene locus have been deposited in the GeneBank database and are available under Accession No. AF095574. Copyright © 1999 John Wiley & Sons, Ltd.     

Construction of R16F and D19L mutations in the loop I of bile salt hydrolase (BSH) enzyme from Lactobacillus plantarum B14 and structural and functional analysis of the mutant BSHs

Bile salt hydrolase (BSH), found commonly in intestinal species of Lactobacillus and Bifidobacterium, catalyzes the hydrolysis of glycine or taurine-conjugated bile acids into the amino acids and free bile acids. Deconjugated bile acids potentially play an important role in the reduction of blood cholesterol level and formation of some gastrointestinal diseases such as cholestasis, gallstone formation, and colon cancer. Although the crystal and three-dimensional structures of BSH enzyme are known, the working mechanism of catalytic activity of such an important BSH enzyme is not known very well. Previous in silico analysis of multiple BSH has identified that Arginine-16 (R16) and Aspartate-19 (D19) were catalytically important residues in the active site of BSH. To confirm the function of these amino acids, in this study, BSH enzyme from Lactobacillus plantarum B14 strain was cloned into Escherichia coli and strictly conserved polar R16 and D19 amino acids of BSH enzyme were substituted for hydrophobic Phenylalanine-16 (F16) and Leucine-19 (L19) amino acids, respectively, by polymerase chain reaction (PCR)-based site-directed mutagenesis. The effects of the mutations on catalytic activity and structure of the BSH enzymes were detected by ninhidrin assay and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis, respectively. Research results showed that although F16 mutation led to loss of enzyme activity completely, L19 mutation led to abolishment of the synthesis of BSH enzyme. These results indicated that R16 and D19 amino acids located in loop I of the BSH enzyme might be critical for catalytic activity and assembly of the BSH enzyme respectively.     

Active immunization against the proregions of GDF9 or BMP15 alters ovulation rate and litter size in mice

The transforming growth factor β (TGFB) superfamily proteins bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9), are essential for mammalian fertility. Recent in vitro evidence suggests that the proregions of mouse BMP15 and GDF9 interact with their mature proteins after secretion. In this study, we have actively immunized mice against these proregions to test the potential in vivo roles on fertility. Mice were immunized with either N- or C-terminus proregion peptides of BMP15 or GDF9, or a full-length GDF9 proregion protein, each conjugated to keyhole limpet hemocyanin (KLH). For each immunization group, ovaries were collected from ten mice for histology after immunization, while a further 20 mice were allowed to breed and litter sizes were counted. To link the ovulation and fertility data of these two experimental end points, mice were joined during the time period identified by histology as being the ovulatory period resulting in to the corpora lutea (CL) counted. Antibody titers in sera increased throughout the study period, with no cross-reactivity observed between BMP15 and GDF9 sera and antigens. Compared with KLH controls, mice immunized with the N-terminus BMP15 proregion peptide had ovaries with fewer CL (P<0.05) and produced smaller litters (P<0.05). In contrast, mice immunized with the full-length GDF9 proregion not only had more CL (P<0.01) but also had significantly smaller litter sizes (P<0.01). None of the treatments affected the number of antral follicles per ovary. These findings are consistent with the hypothesis that the proregions of BMP15 and GDF9, after secretion by the oocyte, have physiologically important roles in regulating ovulation rate and litter size in mice.     

Mutations in the Lcb2p subunit of serine palmitoyltransferase eliminate the requirement for the TSC3 gene in Saccharomyces cerevisiae

Serine palmitoyltransferase catalyses the committed step in sphingolipid synthesis, the condensation of serine with palmitoyl-CoA to form 3-ketosphinganine. Two proteins, Lcb1p and Lcb2p, are essential for enzyme activity and a third protein, the 80-amino acid Tsc3p, stimulates the activity of serine palmitoyltransferase several-fold. Tsc3p physically associates with a complex of Lcb1p-Lcb2p and stimulates enzyme activity posttranslationally, but its precise function is not known. Tsc3p is essential for cell viability only at elevated temperatures, although serine palmitoyltransferase activity is reduced in the tsc3 delta mutant, even at permissive growth temperatures. Tsc3p is apparently not required for any essential process besides stimulation of serine palmitoyltransferase at 37 degrees C, since providing sphingoid bases to the growth medium reverses the temperature-sensitive growth phenotype of the tsc3 delta mutant. To gain further insight into the function of Tsc3p, suppressor mutants that eliminate the Tsc3p requirement for growth at 37 degrees C were isolated and characterized. These studies show that dominant mutations in the Lcb2p subunit of serine palmitoyltransferase suppress the temperature-sensitive growth phenotype of the tsc3 delta null mutant by increasing the Tsc3p-independent serine palmitoyltransferase activity.     

Proteomic analysis of porcine oocytes during in vitro maturation reveals essential role for the ubiquitin C-terminal hydrolase-L1

In this study, we performed proteomic analysis of porcine oocytes during in vitro maturation. Comparison of oocytes at the initial and final stages of meiotic division characterized candidate proteins that were differentially synthesized during in vitro maturation. While the biosynthesis of many of these proteins was significantly decreased, we found four proteins with increased biosynthetic rate, which are supposed to play an essential role in meiosis. Among them, the ubiquitin C-terminal hydrolase-L1 (UCH-L1) was identified by mass spectrometry. To study the regulatory role of UCH-L1 in the process of meiosis in pig model, we used a specific inhibitor of this enzyme, marked C30, belonging to the class of isatin O-acyl oximes. When germinal vesicle (GV) stage cumulus-enclosed oocytes were treated with C30, GV breakdown was inhibited after 28 h of culture, and most of the oocytes were arrested at the first meiosis after 44 h. The block of metaphase I-anaphase transition was not completely reversible. In addition, the inhibition of UCH-L1 resulted in elevated histone H1 kinase activity, corresponding to cyclin-dependent kinase(CDK1)-cyclin B1 complex, and a low level of monoubiquitin. These results supported the hypothesis that UCH-L1 might play a role in metaphase I-anaphase transition by regulating ubiquitin-dependent proteasome mechanisms. In summary, a proteomic approach coupled with protein verification study revealed an essential role of UCH-L1 in the completion of the first meiosis and its transition to anaphase.     

In vivo Mutational Analysis of Highly Conserved Amino Acid Residues of the Small Subunit Cpa1p of the Carbamylphosphate Synthetase of Saccharomyces cerevisiae

The role of selected amino acid residues located in the putative catalytic domain and of two conserved histidine residues within the small subunit of the carbamylphosphate synthetase (CPS) specific to the arginine biosynthesis pathway of the yeast Saccharomyces cerevisiae was studied using site-directed mutagenesis to change all residues to aspartic acid. Carbamylphosphate synthesis catalysed by modified CPS was tested in vivo. The C264D, H307D and H349D mutants were unable to grow on minimal medium, indicating the importance of these three residues for efficient CPS activity, whereas, four other mutated residues located in the catalytic site (including a proline residue) do not affect the growth rate. These results in comparison to those obtained with the CPS of Escherichia coli, implicate residues Cys 264 and His 349 in the glutaminase catalytic activity, and His 307 in the binding of glutamine to the active site. Using these three defective mutants, we investigated the in vivo utilization of ammonia by CPS. C264D and H307D mutants are able to use ammonia as a substrate when provided in sufficiently high concentrations (up to 200 mm). The H349D mutant, however, did not grow even at ammonium sulfate concentrations above 400 mm, suggesting that this substitution is critical to NH₃-dependent CPS activity although the ammonia binding site is presumably located within the large subunit of the enzyme. © 1997 by John Wiley & Sons, Ltd.     

万古霉素和去甲万古霉素检测方法研究进展

万古霉素和去甲万古霉素化学结构、药理性质和抗菌作用相似,均属于糖肽类抗生素,被广泛应用于细菌感染的治疗,尤其是一些超级细菌。临床上,药物治疗方案是依据血液中药物含量而确立的。另外药物的不合理使用会造成其在农产品中的残留,对人们的食用安全具有危害性,因此需要对农产品中药物残留进行监测,并建立高效的检测方法刻不容缓。本文对万古霉素和去甲万古霉素的检测方法进行综述,分别介绍了万古霉素在医疗卫生领域和动物源食品中不同的检测方法,包括高效液相色谱法(high performance liquid chromatography,HPLC)、液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry,LC-MS/MS)、酶放大免疫法(enzyme-multiplied immunoassay technique,EMIT)、酶联免疫法(enzyme linked immunosorbent assay,ELISA)、荧光偏振免疫法(fluorescence polarization immunoassay,FPIA)等,详细介绍了上述方法的检测原理、研究现现状及实际应用情况,并对其发展趋势进行了展望。     

Functional analysis of the cysteine residues and the repetitive sequence of Saccharomyces cerevisiae Pir4/Cis3: the repetitive sequence is needed for binding to the cell wall beta-1,3-glucan

Identification of PIR/CIS3 gene was carried out by amino-terminal sequencing of a protein band released by beta-mercaptoethanol (beta-ME) from S. cerevisiae mnn9 cell walls. The protein was released also by digestion with beta-1,3-glucanases (laminarinase or zymolyase) or by mild alkaline solutions. Deletion of the two carboxyterminal Cys residues (Cys(214)-12aa-Cys(227)-COOH), reduced but did not eliminate incorporation of Pir4 (protein with internal repeats) by disulphide bridges. Similarly, site-directed mutation of two other cysteine amino acids (Cys(130)Ser or Cys(197)Ser) failed to block incorporation of Pir4; the second mutation produced the appearance of Kex2-unprocessed Pir4. Therefore, it seems that deletion or mutation of individual cysteine molecules does not seem enough to inhibit incorporation of Pir4 by disulphide bridges. In fks1Delta and gsc2/fks2Delta cells, defective in beta-1,3-glucan synthesis, modification of the protein pattern found in the supernatant of the growth medium, as well as the material released by beta-ME or laminarinase, was evident. However, incorporation of Pir4 by both disulphide bridges and to the beta-1,3-glucan of the cell wall continued. Deletion of the repetitive sequence (QIGDGQVQA) resulted in the secretion and incorporation by disulphide bridges of Pir4 in reduced amounts together with substantial quantities of the Kex2-unprocessed Pir4 form. Pir4 failed to be incorporated in alkali-sensitive linkages involving beta-1,3-glucan when the first repetitive sequence was deleted. Therefore, this suggests that this sequence is needed in binding Pir4 to the beta-1,3-glucan.     

脱氮硫杆菌硫转移酶SoxAX的建模及分子对接

硫氧化酶系统(Sulfur oxidizing,Sox)在脱氮硫杆菌(Thiobacillus denitrificans,Td)的硫代谢过程中起着至关重要的作用,其核心为Sox AXYZB,硫化物需先经Sox AX蛋白催化并转移到Sox YZ上才能进行Sox通路后续的硫氧化反应,而目前尚无脱氮硫杆菌Sox AX蛋白结构解析的报道。本文采用反向折叠法构建了Sox AX蛋白的二聚体结构并验证其合理性,并通过分子对接实验探讨Sox AX蛋白模型与硫代硫酸盐、硫化氢和亚硫酸盐等不同底物结合在构型与能量上的差异。结果表明,构建的Sox AX二聚体蛋白结构相对合理,氢键是维持Sox AX二聚体结合的主要作用力,10个短强氢键和1个π键作用力参与维持二聚体结构的稳定,Sox A的Arg160等6个残基及Sox X的Asn15等8个残基对维持二聚体结构有重要作用。分子对接试验显示氢键是维持底物与Sox AX结合的主要作用力,与底物结合的关键氨基酸为Arg210、Cys214和Gln217。在三种底物与酶结合的亲和力中以硫化氢最高、硫代硫酸盐次之、亚硫酸盐最低。     

Novel poly-gamma-glutamate-processing enzyme catalyzing gamma-glutamyl DD-amidohydrolysis

The pgdS gene product of Bacillus subtilis, PgdS, cleaves poly-gamma-glutamate (PGA) in an endo-peptidase-like fashion. However, its catalytic property remains obscure. In this study, a simple assay for the PgdS enzyme using 1-fluoro-2,4-dinitrobenzene was developed, and some characteristics of PgdS, such as optimal pH, were examined. The enzyme was strongly inhibited by a thiol-modifying reagent, suggesting that it possesses essential cysteine residue(s) in catalysis. PgdS exhibited a high affinity to PGA that consisted mainly of D-glutamate residues, but no affinity to PGA composed only of L-glutamate residues (L-PGA). The enzyme processed DL-copolymer-type PGA (DL-PGA) with an average molecular mass of 1,000 kDa to a high-molecular-mass L-glutamate-rich fragment (average 200 kDa), the L-rich PGA fragment, and low-molecular-mass fragment composed mostly of D-glutamate residues (average 5 kDa), D-fragment. To deepen our understanding of the catalytic property of the PgdS enzyme, we analyzed the structures of the N- and C-terminal regions and found that D-glutamyl residues successively lie even at both ends of the L-rich PGA fragment. Our observations indicate that PgdS is a novel endo-peptidase that specifically cleaves the gamma-amide linkage between two D-glutamate residues in PGA, i.e., gamma-glutamyl DD-amidohydrolase. The enzyme is possibly useful in the biochemical processing of B. subtilis DL-PGA.