Proline-specific Peptidase Research Articles

Proline-specific peptidase activities (DPP4, PRCP, FAP and PREP) in plasma of hospitalized COVID-19 patients

BackgroundCOVID-19 patients experience several features of dysregulated immune system observed in sepsis. We previously showed a dysregulation of several proline-selective peptidases such as dipeptidyl peptidase 4 (DPP4), fibroblast activation protein alpha (FAP), prolyl oligopeptidase (PREP) and prolylcarboxypeptidase (PRCP) in sepsis. In this study, we investigated whether these peptidases are similarly dysregulated in hospitalized COVID-19 patients. MethodsFifty-six hospitalized COVID-19 patients and 32 healthy controls were included. Enzymatic activities of DPP4, FAP, PREP and PRCP were measured in samples collected shortly after hospital admission and in longitudinal follow-up samples. ResultsCompared to healthy controls, both DPP4 and FAP activities were significantly lower in COVID-19 patients at hospital admission and FAP activity further decreased significantly in the first week of hospitalization. While PRCP activity remained unchanged, PREP activity was significantly increased in COVID-19 patients at hospitalization and further increased during hospital stay and stayed elevated until the day of discharge. ConclusionThe changes in activities of proline-selective peptidases in plasma are very similar in COVID-19 and septic shock patients. The pronounced decrease in FAP activity deserves further investigation, both from a pathophysiological viewpoint and as its utility as a part of a biomarker panel.

Ethanol tolerance assessment in recombinant E. coli of ethanol responsive genes from Lactobacillus buchneri NRRL B-30929.

We previously identified specific proteins associated with ethanol stress response in a Lactobacillus buchneri strain capable of growing in 10% ethanol. In the current study, the exceptional roles of ethanol responsive genes are examined to determine if they can increase ethanol tolerance in E. coli host cells. The recombinant strains carrying ethanol responsive genes were subjected to growth analyses in media with and without 4% ethanol. Among the expression of these genes and growth analyses of the recombinant strains in ethanol, six genes Lbuc_0522 (NADPH-dependent methylglyoxal reductase), Lbuc_0354 (succinate semialdehyde dehydrogenase), Lbuc_1211(threonyl_tRNA synthetase), Lbuc_2051 (nitroreductase), Lbuc_0707 (branched chain amino acid aminotransferase) and Lbuc_1852 (proline-specific peptidase) conferred host cells tolerance to 4% ethanol. Six genes Lbuc_1523 (phage major capsid protein, HK 97 family), Lbuc_1319 (phosphoglycerate kinase), Lbuc_0787 encoding fumarylacetoacetate hydrolase, Lbuc_1219 encoding UDP-N-acetylmuramate-L-alanine ligase, Lbuc_0466 encoding ornithine carbamoyltransferase and Lbuc_0858 encoding glycine hydroxymethyltransferase showed no impact on growth in media with 4% ethanol with IPTG induction when compared with E. coli carrying control pET28b plasmid. The expression of two genes Lbuc_1557 (S-layer glycoprotein) and Lbuc_2157 (6-phosphogluconate dehydrogenase) resulted ethanol sensitivity phenotype.

Preparation and Purification of Recombinant Dipeptidyl Peptidase 4 from Tenebrio molitor

Dipeptidyl peptidase 4—is a unique proline-specific peptidase, capable to hydrolyze the bonds, formed by proline amino acid residue, cleaving dipeptides from N-terminus of peptides and proteins, containing this imino acid in P1 position. Recombinant dipeptidyl peptidase 4 from the insect Tenebrio molitor was prepared for the first time in the Pichia pastoris protein expression system; a method for its purification was proposed. The authenticity of the obtained recombinant enzyme was confirmed by mass spectrometry. The use of the obtained preparation of the T. molitor enzyme is promising for the hydrolysis of resistant to proteolysis proline-rich peptides and proteins, particularly for prolamins – the main storage proteins of cereal seeds, since they are not fully hydrolyzed by human digestive enzymes and cause autoimmune gastrointestinal celiac disease in the susceptible group of people.

Экспериментальное тревожно-депрессивное состояние у крыс, вызванное неонатальным действием ингибитора дипептидилпептидазы-IV дипротина А: эффекты имипрамина

В наших предыдущих исследованиях было показано, что ингибитор пролинспецифической пептидазы дипептидилпептидазы-IV (ДП-IV, EC 3.4.14.5) трипептид дипротин А, введенный крысам в 5-18 постнатальные дни, приводит к развитию у крыс подросткового возраста и взрослых животных эмоционально-мотивационных расстройств. Такие расстройства можно рассматривать как модель смешанного тревожно-депрессивного состояния. Однако специальных исследований по валидности данной модели проведено не было. Цель настоящей работы состояла в проверке влияния трициклического антидепрессанта имипрамина (ИМИ) на депрессивноподобное поведение крыс и уровень кортикостерона в сыворотке крови животных на модели смешанного тревожно-депрессивного состояния. Методика. У крыс в возрасте одного и двух мес. определяли уровень тревожности в автоматизированном тесте «Приподнятый крестообразный лабиринт» и оценивали депрессивноподобное поведение в тесте принудительного плавания. ИМИ вводили взрослым животным в течение 10 дней (20 мг/кг/день, интрагастрально). Уровень кортикостерона в сыворотке крови определяли методом твердофазного иммуноферментного анализа. Результаты. Неонатальное действие дипротина А приводило к повышению тревожности у крыс в возрасте 1 мес. Депрессивноподобное поведение обнаружено у животных в возрасте одного и двух мес. ИМИ нормализовал поведение животных в тесте принудительного плавания и снижал уровень кортикостерона в сыворотке крови крыс. Кроме того, ИМИ снижал вес крыс. Заключение. Результаты исследования свидетельствуют в пользу адекватности модели смешанного тревожно-депрессивного расстройства, возникающего у крыс вследствие действия ингибитора ДП-IV дипротина А на второй-третьей неделях постнатального развития, клиническому прообразу заболевания по критериям «внешней схожести», прогностической и конструкционной валидности. Previously, we have shown that the inhibitor of proline-specific peptidase, dipeptidyl peptidase-IV (DP-IV, EC 3.4.14.5), tripeptide diproptin A administered on postnatal days 5-18 induced emotional and motivational disorders in adolescent and adult rats. These disorders can be considered a model of a mixed anxiety-depression-like disorder. However, validation studies of this model are not available. The aim of this work was to test the effect of the tricyclic antidepressant, imipramine (IMI), on depressive-like behavior in rats and the level of serum corticosterone using the model of mixed anxiety-depressive state. Methods. The level of anxiety was assessed by the automated Elevated Plus Maze test and the depressive-like behavior was evaluated by the forced swimming test in one- and two-month old rats. IMI was administered to adult animals for ten days (20 mg/kg a day, intragastrically). Serum corticosterone concentrations were measured using ELISA. Results. The neonatal exposure to diprotin A increased anxiety in one-month old rats. The depressive-like behavior was observed in animals aged one and two months. IMI normalized behavior of animals in the forced swimming test and reduced serum levels of corticosterone. Also, IMI reduced body weight of rats. Conclusion. The results of the study evidenced adequacy of the model of mixed anxiety-depressive state induced by the DP-IV inhibitor, diprotin A, on the second and third postnatal weeks to the clinical prototype of disease according to criteria of face validity, predictive and construct validity.

Deficiency of aminopeptidase P1 causes behavioral hyperactivity, cognitive deficits, and hippocampal neurodegeneration.

Metabolic diseases affect various organs including the brain. Accumulation or depletion of substrates frequently leads to brain injury and dysfunction. Deficiency of aminopeptidase P1, a cytosolic proline-specific peptidase encoded by the Xpnpep1 gene, causes an inborn error of metabolism (IEM) characterized by peptiduria in humans. We previously reported that knockout of aminopeptidase P1 in mice causes neurodevelopmental disorders and peptiduria. However, little is known about the pathophysiological role of aminopeptidase P1 in the brain. Here, we show that loss of aminopeptidase P1 causes behavioral and neurological deficits in mice. Mice deficient in aminopeptidase P1 (Xpnpep1-/- ) display abnormally enhanced locomotor activities in both the home cage and open-field box. The aminopeptidase P1 deficiency in mice also resulted in severe impairments in novel-object recognition, the Morris water maze task, and contextual, but not cued, fear memory. These behavioral dysfunctions were accompanied by epileptiform electroencephalogram activity and neurodegeneration in the hippocampus. However, mice with a heterozygous mutation for aminopeptidase P1 (Xpnpep1+/- ) exhibited normal behaviors and brain structure. These results suggest that loss of aminopeptidase P1 leads to behavioral, cognitive and neurological deficits. This study may provide insight into new pathogenic mechanisms for brain dysfunction related to IEMs.

Prolidase is a critical enzyme for complete gliadin digestion in Tenebrio molitor larvae.

Prolidase is a proline-specific metallopeptidase that cleaves imidodipeptides with C-terminal Pro residue. Prolidase was purified and characterized from the Tenebrio molitor larval midgut. The enzyme was localized in the soluble fraction of posterior midgut tissues, corresponding to a predicted cytoplasmic localization of prolidase according to the structure of the mRNA transcript. Expression of genes encoding prolidase and the major digestive proline-specific peptidase (PSP)-dipeptidyl peptidase 4-were similar. The pH optimum of T. molitor prolidase was 7.5, and the enzyme was inhibited by Z-Pro, indicating that it belongs to type I prolidases. In mammals, prolidase is particularly important in the catabolism of a proline-rich protein-collagen. We propose that T. molitor larval prolidase is a critical enzyme for the final stages of digestion of dietary proline-rich gliadins, providing hydrolysis of imidodipeptides in the cytoplasm of midgut epithelial cells. We propose that the products of hydrolysis are absorbed from the luminal contents by peptide transporters, which we have annotated in the T. molitor larval gut transcriptome. The origin of prolidase substrates in the insect midgut is discussed in the context of overall success of grain feeding insects.

Characterization of cross-linked enzyme aggregates (CLEAs) of the fusion protein FUS-PepN_PepX and their application for milk protein hydrolysis

The use of general and specific exopeptidases is of great interest for the hydrolysis of food proteins. Protein hydrolysates with a high degree of hydrolysis and, therefore, a reduced bitterness and improved antioxidative capacity can be produced due to the synergistic specificities of the general aminopeptidase PepN and the proline-specific peptidase PepX. These two activities were previously combined in a fusion protein and the latter showed both specific activities. However, due to its solubility an application of the fusion protein in continuous processes will be complicated in the future. Therefore, the aim of this study was the production, characterization and use of cross-linked enzyme aggregates (CLEAs) from the fusion protein (FUS-PepN_PepX CLEAs). The FUS-PepN_PepX CLEAs produced had activity for both specific enzymes. The biochemical characteristics determined (e.g., pH and temperature optima, environmental conditions) showed that the CLEAs are suitable for application in a complex matrix, such as food protein hydrolysates. The relative degree of hydrolysis of a prehydrolyzed casein solution was increased by 100% and the hydrolysate obtained showed a strong antioxidative capacity (ABTS-IC50 value: 7.85 µg mL−1). The stability against NaCl and the possibility of using ethanol as a microbial hurdle as well as the size of the FUS-PepN_PepX CLEAs seem promising for an application in an enzyme membrane reactor in the future. In summary, using these CLEAs, casein hydrolysates with a high degree of hydrolysis, a potentially reduced bitterness and high antioxidative capacity can be produced.

AN-PEP, Proline-Specific Endopeptidase, Degrades All Known Immunostimulatory Gluten Peptides in Beer Made from Barley Malt

The haze-forming peptides and proteins present in beer mainly originate from the grains used. Such grains, typically barley and wheat, also incorporate gluten. Although partially hydrolyzed during brewing, glutencontaining protein material remains present in the final beers. Glutensensitive people might therefore not be able to consume beer without an adverse response. AN-PEP, the proline-specific peptidase in Brewers Clarex, is commercially applied to selectively degrade proline-rich, haze-forming peptides and proteins during beer fermentation. The unusually high percentage of proline in known celiac-related gluten epitopes suggests that they form ideal substrates for AN-PEP as well. We confirmed that in beers prepared with AN-PEP, gluten levels were well below 20 mg/kg based on the established competitive R5 ELISA method. We used a sensitive LC-MS/MS method developed in-house to identify the peptides. Only in beers brewed through a conventional process could we find epitope-containing peptides, even in beers that contained less than 20 mg/kg of gluten based on the ELISA. So even though the MS method is qualitative and not quantitative, it provided a more detailed view of the fate of gluten during brewing. Specifically, these data indicate that AN-PEP is able to degrade all known immunogenic gluten epitopes in beer. We conclude that apart from its current application as a beer stabilizer, AN-PEP has the additional benefit of exhaustive degradation of all potentially problematic gluten epitopes.

A fusion protein consisting of the exopeptidases PepN and PepX-production, characterization, and application.

Nowadays, general and specific aminopeptidases are of great interest, especially for protein hydrolysis in the food industry. As shown previously, it is confirmed that the general aminopeptidase N (PepN; EC 3.4.11.2) and the proline-specific peptidase PepX (EC 3.4.14.11) from Lactobacillus helveticus ATCC 12046 show a synergistic effect during protein hydrolysis which results in high degrees of hydrolysis and reduced bitterness. To combine both activities, the enzymes were linked and a fusion protein called PepN-L1-PepX (FUS-PepN-PepX) was created. After production and purification, the fusion protein was characterized. Some of its biochemical characteristics were altered in favor for an application compared to the single enzymes. As an example, the optimum temperature for the PepN activity increased from 30°C for the single enzyme to 35°C for FUS-PepN. In addition, the temperature stability of PepX was higher for FUS-PepX than for the single enzyme (50% compared to 40% residual activity at 50°C after 14days, respectively). In addition, the disulfide bridge-reducing reagent β-mercaptoethanol did not longer inactivate the FUS-PepN activity. Furthermore, the K M values decreased for both enzyme activities in the fusion protein. Finally, it was found that the synergistic hydrolysis performance in a casein hydrolysis was not reduced for the fusion protein. The increase of the relative degree of hydrolysis of a prehydrolyzed casein solution was the same as it was for the single enzymes. As a benefit, the resulting hydrolysate showed a strong antioxidative capacity (ABTS-IC50 value: 5.81μgmL(-1)).

Degradation of gluten in rye sourdough products by means of a proline-specific peptidase

The gluten content of rye sourdough during fermentation was monitored by a competitive ELISA based on the R5 antibody. Although a time-dependent decrease was found, the gluten content was not reduced below the threshold for gluten-free foods of 20 mg/kg, even after prolonged fermentation. Instead, Aspergillus niger prolyl endopeptidase (AN-PEP) extensively degraded gluten concentrations of up to 80,000 mg/kg in rye flour, rye sourdough, and sourdough starter under distinct temperatures and pH values. The enzyme did not lead to inactivation of the microorganisms in the sourdough starter. Gluten-free rye flour alone or in combination with sourdough starter was used to produce gluten-free bread, which was evaluated for its sensory properties. Whereas gluten-free sourdough bread had poor sensory attributes compared to a conventional rye bread used as reference, the replacement of sourdough by egg proteins yielded gluten-free bread comparable to the reference and with higher sensory quality than bread prepared from naturally gluten-free ingredients. Therefore, the feasibility of producing high-quality bread from originally gluten-containing cereals such as rye by means of treatment with AN-PEP has been shown. Rye products rendered gluten-free in this manner have the potential to increase the choice of high-quality gluten-free foods for celiac patients.

Proteomic analyses of ethanol tolerance inLactobacillus buchneriNRRL B-30929

The Lactobacillus buchneri NRRL B-30929 strain, isolated from a fuel ethanol (EtOH) production facility, exhibits high tolerance to environmental EtOH concentrations. This study aimed to identify proteins produced by B-30929 in response to environmental EtOH. Cellular proteins expressed by B-30929 growing in media with 10 versus 0% EtOH were compared by 2DE, followed by in-gel digestion and MALDI-MS analyses. Twenty EtOH responsive proteins were identified. These include a proline-specific peptidase (Lbuc_1852); a membrane protein (Lbuc_0921), two general stress-related proteins including a 10 kDa chaperonin (GroESL Lbuc_1359) and a 29 kDa member of the HK 97 family (Lbuc_1523); metabolic enzymes involving redox potential balances (Lbuc_2051 and Lbuc_0522) and carbohydrate fermentation (Lbuc_1319 and Lbuc_2157); nitrogen, amino acid, and fatty acid metabolism proteins (Lbuc_1994, Lbuc_0446, Lbuc_0858, Lbuc_0707, and Lbuc_0787). These changes suggested B-30929 cells respond to EtOH by degradation of available proteins and fatty acids and increased production of specific enzymes and molecular chaperons. These results can be used to guide genetic modifications to increase EtOH tolerance in industrial biocatalysts. The data have been deposited to World-2DPAGE (http://world-2dpage.expasy.org/repository/0068/; username liu, password 1h8d6Mg1).

Degradation of Gluten in Wheat Bran and Bread Drink by Means of a Proline-Specific Peptidase

Gluten-free wheat bran and bread drink were produced by degrading gluten with Aspergillus niger prolyl endopeptidase (AN-PEP). For this purpose, bran from native and germinated wheat grains as well as bread drink were mixed with AN-PEP and incubated at 50°C under different conditions. The amount of enzyme activity (1.2 • 10-4 - 8.7 • 10-1 U), the incubation time (0-72 h), and the pH value (1.0-9.0) were systematically altered. The gluten content was monitored by a competitive ELISA using the R5 antibody. Gluten in two wheat bran samples produced in the laboratory was degraded below the threshold for gluten-free foods of 20 mg/kg. This was not possible in a commercial wheat bran sample that had potentially been heat-treated leading to strong crosslinking of gluten by incorporation of gliadins into the glutenin fraction, possible formation of isopeptide crosslinks and, thus, poor digestibility. In contrast, gluten in bread drink was easily degraded after a short incubation time of 30 min and low AN-PEP activity. No significant differences of the quality parameters between treated and untreated products were found. Remarkably, bran from germinated grains was strongly enriched in nutritionally positive compounds such as dietary fiber and folates compared to native grains. Thus, wheat bran from germinated grains rendered gluten-free by treatment with AN-PEP can contribute to increasing the nutritional value of the gluten-free diet.

Deregulation of allosteric response of Lactococcus lactis prolidase and its effects on enzyme activity

The allosteric behaviour of Lactococcus lactis prolidase (Xaa-Pro dipeptidase) of this proline-specific peptidase was investigated where it was hypothesized that intersubunit interactions between a loop structure and three residues near the active site contributed to this behaviour. Seven mutant prolidases were constructed, and it was observed that the loopless mutant and His303 substitution inactivated the enzyme. Ser307 substitution revealed that this residue influenced the substrate binding, as judged from its kinetic constants and substrate specificity; however, this residue did not contribute to allostery of prolidase. R293S mutation resulted in the disappearance of the allosteric behaviour yielding a Hill constant of 0.98 while the wild type had a constant of 1.58. In addition, the R293S mutation suppressed the substrate inhibition that was observed in other mutants and wild type. The K m value of R293S was 2.9-fold larger and V max was approximately 50% less as compared to the wild type. The results indicated that Arg293 increased the affinity for substrates while introducing allosteric behaviour and substrate inhibition. Computer modelling suggested that negative charges on the loop structure interacted with Arg293 and Ser307 to maintain these characteristics. It was, therefore, concluded that Arg293, His303, Ser307 and the loop contributed to the enzyme's allosteric characteristics.

The purification and characterisation of novel dipeptidyl peptidase IV-like activity from bovine serum

The discovery of a potentially novel proline-specific peptidase from bovine serum is presented which is capable of cleaving the dipeptidyl peptidase IV (DPIV) substrate Gly-Pro-MCA. The enzyme was isolated and purified with the use of Phenyl Sepharose Hydrophobic Interaction, Sephacryl S-300 Gel Filtration, and Q-Sephacryl Anion Exchange, producing an overall purification factor of 257. SDS PAGE resulted in a monomeric molecular mass of 158 kDa while size exclusion chromatography generated a native molecular mass of 328 kDa. The enzyme remained active over a broad pH range with a distinct preference for a neutral pH range of 7–8.5. Chromatofocusing and isoelectric focusing (IEF) revealed the enzyme’s isoelectric point to be 4.74. DPIV-like activity was not inhibited by serine protease inhibitors but was by the metallo-protease inhibitors, the phenanthrolines. The enzyme was also partially inhibited by bestatin. Substrate specificity studies proved that the enzyme is capable of sequential cleavage of bovine β-Casomorphin and Substance P. The peptidase cleaved the standard DPIV substrate, Gly-Pro-MCA with a K M of 38.4 μM, while Lys-Pro-MCA was hydrolysed with a K M of 103 μM. The DPIV-like activity was specifically inhibited by both Diprotin A and B, non-competitively, generating a K i of 1.4×10 −4 M for both inhibitors. Ile-Thiazolidide and Ile-Pyrrolidide both inhibited competitively with an inhibition constant of 3.7×10 −7 and 7.5×10 −7 M, respectively. It is concluded that bovine serum DPIV-like activity share many biochemical properties with DPIV and DPIV-like enzymes but not exclusively, suggesting that the purified peptidase may play an important novel role in bioactive oligopeptide degradation.

A continuous fluorimetric assay for aminopeptidase P detailed analysis of product inhibition

Aminopeptidase P (APP; EC 3.4.11.9) is a proline-specific peptidase hydrolyzing N-terminal Xaa-Pro peptide bonds. On the basis of its unique substrate specificity it is difficult to determine enzyme activity and to estimate potential enzyme inhibitors. In this report, we describe the synthesis of a new fluorogenic substrate to assay APP. The substrate was characterized using Escherichia coli APP and rat intestine APP. The compound contains the fluorogenic 2-aminobenzoyl residue and 4-nitroanilide as internal quencher. Both enzymes hydrolyze the substrate Lys( N ε -2-aminobenzoyl)-Pro-Pro-4-nitroanilide at the Lys-Pro peptide bond with K m values in the micromolar range. Lys( N ε -2-aminobenzoyl)-Pro-Pro-4-nitroanilide is the best substrate of APP from rat intestine that is known with a K m value of 3.54 μM and a second-order rate constant of 1,142,000 M −1 s −1. Unfortunately, product inhibition occurs. Inhibition studies using the hydrolysis product Pro-Pro-4-nitroanilide demonstrate a linear mixed-type mechanism with a K i value of 20.8 μM and an α value of 5.1 for rat APP and a K i value of 76.1 μM and an α value of 0.4 for E. coli APP, respectively. Furthermore, the hydrolysis of the fluorogenic APP substrate catalyzed by prolyl oligopeptidase was investigated.

Growth phase and growth medium effects on the peptidase activities of Lactobacillus helveticus

The effect of growth phase, growth medium and storage conditions on the peptidase activities of Lactobacillus helveticus DPC 4571 were examined. Cell free extracts (CFEs) were prepared from both mid-log and stationary phase cells grown in either 10% (w/v) reconstituted skim milk (RSM) or MRS pH 5.4 broth. In general, Lb. helveticus DPC 4571 was found to possess a broad range of aminopeptidase, dipeptidase, tripeptidase, endopeptidase and proline-specific peptidase activities. The stability of these peptidase activities in a CFE of Lb. helveticus DPC 4571 stored at 4°C was variable. The specific activities of the majority of these peptidases were significantly (P<0.05) influenced by both growth phase and growth medium. Cells grown to mid-log phase in RSM were found to have the highest level of peptidase activity.

PROPERTIES OF COMMERCIAL MICROBIAL PROTEINASE PREPARATIONS

ABSTRACT Twenty three commercial microbial proteinase preparations derived from various Bacillus or Aspergillus spp. or from Rhizomucor niveus were assessed for proteolytic activity on azocasein at pH 5.5 or 7.0, or specificity on sodium caseinate at pH 5.5 and semi-quantitatively assessed for esterase, lipase, trypsin, chymotrypsin, general aminopeptidase, phosphatase and glycosidase activities using the API-ZYM system. Selected preparations were further assayed for peptidase, esterase and lipase activities at pH 7.0. The proteolytic activity of the Bacillus preparations was greater at pH 7.0, while that of the Aspergillus and Rhizomucor preparations was greater at pH 5.5. All the Bacillus preparations contained one of two main proteolytic activities, thought to be either bacillolysin or subtilisin. Most of the Aspergillus preparations contained the same proteinase, thought to be aspergillopepsin I, but two preparations appeared to contain a different unidentified proteinase. The proteolytic specificity of the Rhizomucor preparation was different from the Bacillus or Aspergillus preparations; thought to be rhizopuspepsin. According to the results of the API-ZYM system, all preparations contained enzyme activities in addition to their main proteolytic activity, with the Aspergillus and Rhizomucor preparations containing the highest levels and widest range of activities. Generally preparations derived from Aspergillus contained the highest level of general, proline and endopeptidase activities, with the Bacillus preparations conspicuous by the absence of general and proline-specific peptidase activities, while the Rhizomucor niveus preparation contained little or no general or endopeptidase activity. Esterase activity was found in all of the preparations evaluated, with only two Aspergillus preparations containing lipase activity.

Amino acid sequencing and possible cloning of a new proline specific peptidase from bovine serum

Amino acid sequencing and possible cloning of a new proline specific peptidase from bovine serum

The study of a therapeutically important proline-specific peptidase from bovine serum

The study of a therapeutically important proline-specific peptidase from bovine serum

The study of a therapeutically important prolinespecific peptidase from bovine serum

The study of a therapeutically important prolinespecific peptidase from bovine serum