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PubMed1976

Inactivation of yeast enzymes by proteinase A and B and carboxypeptidase Y from yeast.

Changes in the activities of 15 different enzymes during incubation of a crude yeast extract with the purified yeast proteinases A and B, and carboxypeptidase Y, respectively, have been measured. The spectrum of action of the three proteinases on the enzymes measured differs significantly, increasing or decreasing their activities or having no effect. Incubation of purified cytoplasmic malate dehydrogenase or purified mitochondrial malate dehydrogenase with proteinases A and B results in selective inactivation of the cytoplasmic enzyme, whereas the mitochondrial activity is not affected. Carboxypeptidase Y has no effect on the activity of either dehydrogenase. The results support the idea of selective proteolysis as the mechanism of the earlier observed inactivation of cytoplasmic malate dehydrogenase, initiated by the addition of glucose to intact yeast cells grown on acetate as carbon source ("glucose effect").

Carboxypeptidases↗
PubMed1976

Carboxypeptidase N from pig serum.

Carboxypeptidase N has been purified 865-fold from pig serum. The enzyme has a molecular weight of approximately 315 000. In the presence of dodecylsulfate and mercaptoethanol, it dissociates into three subunits of Mr = 90 000, 50 000, 30 000, respectively. The native enzyme and the subunit of Mr = 90 000 contain carbohydrate; no carbohydrate is found in the subunits of Mr = 50 000 and 30 000. Trypsin transforms carboxypeptidase N into a form having a smaller molecular weight and enhanced activity.

Amino Acids↗
PubMed1976

Effects of yeast proteinase A, proteinase B and carboxypeptidase Y on yeast phosphofructokinase.

Incubation of a crude yeast extract containing phosphofructokinase with proteinase A, proteinase B or carboxypeptidase Y gave the following results: Proteinase B and carboxypeptidase Y did not change the activity of phosphofructokinase during incubation. On the other hand, incubation with proteinase A resulted in a 40-100% activation; continued incubation, however, led to an inactivation of the enzyme. Addition of allosteric effectors did not change the activation or inactivation process. The activated phosphofructokinase was not changed with respect to pH optimum and ATP inhibition. Molecular weight determination of phosphofructokinase in crude extracts in the presence of inhibitors of proteinase A indicated a molecular weight of 700000. Without inhibitors of proteinase A, the molecular weight was determined to be 600 000, while after 40-100% activation by proteinase A, a molecular weight of 500 000 was obtained. The activity profile of proteinase A in density gradients indicated that this enzyme is bound to variety of cellular proteins.

Adenosine Triphosphate↗
PubMed1990

Structure of wheat serine carboxypeptidase II at 3.5-A resolution. A new class of serine proteinase.

The structure of serine carboxypeptidase II from wheat bran has been determined to 3.5-A resolution by multiple isomorphous replacement, solvent flattening, and crystallographic refinement. The amino acid sequence has been fit to the electron density map and the model refined to a conventional crystallographic R factor of 20.9%. The molecule is an alpha + beta protein and contains a "catalytic triad" (Asp338, His397, and Ser146) similar in arrangement to those in chymotrypsin and subtilisin. The -fold of the polypeptide backbone is, however, completely different from those enzymes. This suggests that this is a third example of convergent evolution to a common enzymatic mechanism. The -fold is, on the other hand, surprisingly similar to that of the zinc proteinase carboxypeptidase A.

Amino Acid Sequence↗
PubMed1995

Belactins A and B, new serine carboxypeptidase inhibitors produced by Actinomycete. I. Taxonomy, production, isolation and biological activities.

Belactins A and B, new inhibitors of serine carboxypeptidase were discovered in the fermentation broth of Saccharopolyspora sp. MK19-42F6. They were purified by ethyl acetate extraction, silica gel chromatography, Sephadex LH20 chromatography, Capcellpak C18 SG120 reversed phase HPLC and centrifugal partition chromatography (CPC) following their inhibitory activity against carboxypeptidase Y (CP-Y). The inhibition constants (Ki) of belactins A and B against CP-Y are 0.14 and 0.27 microM respectively. Belactins A and B have highly specific inhibitory activities for CP-Y among various peptidases, have no antimicrobial activities at 100 micrograms/ml and have low toxicities.

Benzamides↗
PubMed1995

Belactins A and B, new serine carboxypeptidase inhibitors produced by Actinomycete. II. Physico-chemical properties, structure determinations and enzymatic inhibitory activities compared with other beta-lactone containing inhibitors.

Belactins A and B, new inhibitors of serine carboxypeptidase were discovered in the fermentation broth of Saccharopolyspora sp. MK19-42F6. The structures of belactins A and B were determined to be 4-[3-[(2-amino-5-chlorobenzoyl)amino]-1,1-dimethyl-2-oxobutyl]-3- methyl-2-oxetanone and 4-[3-[[2-(beta-glucopyranosylamino)-5-chlorobenzoyl]amino]-1,1- dimethyl-2-oxobutyl]-3-methyl-2-oxetanone respectively by various spectral analyses. Belactins A and B do not inhibit esterase or lipase at 100 micrograms/ml but have more specific inhibitory activities towards carboxypeptidase Y (CP-Y) compared with other beta-lactone-containing inhibitors, such as ebelactones A, B and esterastin.

Benzamides↗
PubMed1996

Piperastatin B: a new selective serine carboxypeptidase inhibitor from Streptomyces lavendofoliae MJ908-WF13.

Piperastatin B, a new inhibitor of serine carboxypeptidase was purified from a culture broth of Streptomyces lavendofoliae MJ908-WF13 as a minor component by monitoring its inhibitory activity against carboxypeptidase Y (CP-Y). Its structure was determined to be N-formyl-Val-Thr-Leu-Val-Pip-Leu-Pip (pip: piperazic acid, hexahydropyridadine-3-carboxylic acid). Piperastatin B is a highly specific competitive inhibitor of CP-Y (Ki = 55 nM) with little effect on related enzymes and resembles the major component, piperastatin A, in these respects.

Amino Acids↗
PubMedDate not supplied

[Stability of Streptomyces griseus carboxypeptidase].

Carboxypeptidase of Str. griseus strain 32-13 is stable during storage at a temperature of 10-15 degrees C. Carbohydrates and glycerol in a concentration of 40-80% as well as 0.01 M of L-amino acid prevent the enzyme from thermoinactivation. Anions, such as phosphate, borate, carbonate and acetate, have their inhibitory effect on carboxypeptidase. After the effect of chelate reagents the enzyme activity restores completely only in the presence of Co2+ and partially in the presence of Ni2+ greater than Ca2+ greater than Mn2+ greater than Zn2+.

Amino Acids↗
PubMed1999

[Affinity of exocellular DD-carboxypeptidase/transpeptidase from Saccharopolyspora erythraea PZH TZ-575 to beta-lactam compounds].

The DD-carboxypeptidase/transpeptidases (DD-peptidases) involved in bacterial cell wall metabolism, catalyse the attack of C-terminal D-alanyl-D-alanine peptide bond of the peptydoglycan precursor. These enzymes are inactivated by beta-lactam antibiotics. DD-peptidase from Saccharopolyspora erythraea PZH TZ 64-575 was purified by the use of DEAE-cellulose, Sephadex G-100, Q-Sepharose resins and FPLC (Mono Q). After each step the effluent was concentrated by Amicon ultrafiltration. The purified enzyme showed DD-carboxypeptidase specific activity of 50.9 U/mg. The enzyme exhibited high affinity to beta-lactam compounds e.g. cefamandole, cefapirin, cefradin 1.5-2.6 x 10(-8) M. It was used to screen strains from the Culture Collection of the National Institute of Hygiene in Warsaw for the production of DD-peptidase inhibitors.

Anti-Bacterial Agents↗
PubMed1975

Reversible inactivation of pancreatic deoxyribonuclease A by sodium dodecyl sulfate. Removal of COOH-terminal residues from the denatured protein by carboxypeptidase A.

In the course of experiments on the role of the COOH-terminal residues in pancreatic deoxyribonuclease, we undertook to ascertain whether the presence of sodium dodecyl sulfate would render the normally unavailable terminus susceptible to hydrolysis by carboxypeptidase A. When DNase A is dissolved in 0.005% sodium dodecyl sulfate the protein becomes enzymically inactive when assayed against DNA in the same sodium dodecyl sulfate concentration. The loss of activity caused by treatment with sodium dodecyl sulfate for 1 hour at 45 degrees can be fully restored if the detergent-containing solution is diluted 10-fold into 6 M guanidinium chloride and then 10-fold into a pH 7.0 buffer, 10 mM in CaCl2, prior to a 100-fold dilution for assay. The presence of Ca2+ is essential for the refolding process. If the same degree of dilution is made into sodium dodecyl sulfate-free buffer without the guanidinium chloride step, there is very little reversal of the inactivation. An almost complete loss of regenerable activity is caused by 1 hour of digestion by carboxypeptidase at 45 degrees in the presence of 0.03% sodium dodecyl sulfate. Although up to 6 amino acid residues can be removed from the COOH terminus, the loss of activity can be correlated with the removal of either 1 or 2 amino acid residues (-Leu-Thr) from the COOH-terminal sequence. Thus, DNase A is one of the several enzymes in which residues at the COOH terminus are essential to the active conformation. If the enzyme minus 2 to 6 terminal residues was mixed with a 15-residue COOH-terminal peptide (obtained by cyanogen bromide cleavage), only about 2% activity could be regenerated.

Amino Acid Sequence↗
PubMedDate not supplied

Biosensor analysis of beta-lactams in milk using the carboxypeptidase activity of a bacterial penicillin binding protein.

The applicability of a beta-lactam receptor protein for detection of beta-lactam antibiotics in milk using surface plasmon resonance (SPR) biosensor technology was investigated. The advantage of using a receptor protein instead of antibodies for detection of beta-lactams is that a generic assay, specific for the active form of the beta-lactam structure, is obtained. Two assays based on the enzymatic activity of the DD-carboxypeptidase from Actinomadura R39 were developed, using a Biacore SPR biosensor. The carboxypeptidase converts a tri-peptide into a di-peptide, a reaction which is inhibited in the presence of beta-lactams. Polyclonal antibodies against the 2 peptides were developed and used to measure the amount of enzymatic product formed (di-peptide assay) or the amount of remaining enzymatic substrate (tri-peptide assay), respectively. The 2 assays showed similar performances with respect to detection limits (1.2 and 1.5 microg/kg, respectively) and precision (coefficient of variation <5%) for penicillin G in milk. Several other beta-lactams were detected at or near their respective maximum residue limit. Furthermore, the 2 peptide assays were evaluated against 5 commercial kit tests in the screening of 195 producer milk samples. The biosensor assays showed 0% false-negative and 27% false-positive results, whereas the figures were 0% false-negative and 27-53% false-positive results for other screening tests investigated.

Animals↗
PubMed1991

Structural requirements for nucleophilic substrates of carboxypeptidase Y.

The composition and structural aspects of the amino and carboxylic acid groups required for incorporation into peptides by transpeptidation and inhibition of hydrolysis in carboxypeptidase Y-catalyzed reactions were studied. Separation of these two groups by even one carbon prevents incorporation by transpeptidation and does not inhibit incorporation of other amino acids into model peptides. Substitution of phosphonic or sulfonic acids for the carboxylic acid group also results in loss of incorporation by transpeptidation. Only the sulfonic acid analog of glycine causes inhibition of hydrolysis and this inhibition is lost when serine is included in the reaction. d-Serine is not incorporated by carboxypeptidase Y, and its presence in the reaction mixture does not inhibit the incorporation of the L-isomer.

Carboxypeptidases↗
PubMed1989

C-terminal sequence determination of peptides degraded with carboxypeptidases of different specificities and analyzed by 252-Cf plasma desorption mass spectrometry.

Identification of the truncated peptides by plasma desorption mass spectrometry in C-terminal sequence determination with carboxypeptidases offers several advantages over analysis of the liberated amino acids. It is possible to perform in situ digestion of a nitrocellulose-bound sample already used for molecular weight determination and thus obtain sequence information without further sample consumption. In time-course analysis the analytical information, although not obtained in real time, is sufficiently rapid to adjust the digestion conditions. There is no need for quantitation because the identification is based on molecular weight differences. Sensitivity in the low picomole range is obtainable. The digestion of a number of peptides (900-3500 Da) with carboxypeptidase Y and MII has been monitored. It was found that successive use of the enzymes or use of a mixture of the enzymes was often advantageous. The sequence of up to 10 residues from the C-terminus has been determined for the peptides studied.

Amino Acid Sequence↗
PubMedDate not supplied

[Novel carboxypeptidase for processing of animal nerve tissue enkephalins].

New carboxypeptidase which catalyzes the C-terminal arginine splitting from hexapeptide (an enkephalin precursor) Tyr-Gly-Gly-Phe-Met-Arg is revealed in the cat nerve tissue. The enzyme is activated by cobalt ions, the pH action optimum being 7.6. A relatively high activity of carboxypeptidase in the hypothalamus, midbrain and medulla oblongata permits supposing that it is the key enzyme of the enkephalin processing in areas of the limbic brain system.

Animals↗
PubMed1988

Narrow-bore high-performance liquid chromatography of phenylthiocarbamyl amino acids and carboxypeptidase P digestion for protein C-terminal sequence analysis.

Carboxypeptidase P digestion followed by narrow-bore high-performance liquid chromatography of phenylthiocarbamyl amino acids is employed for polypeptide C-terminal end group and sequence determination. Carboxypeptidase P digestion of polypeptides provides specific cleavage of protein C-terminal amino acids. The digestion offers the advantage that it can be carried out in either 10 mM sodium acetate or water at pH 4.0 in the presence of an enzyme activator, Brij-35. The narrow-bore high-performance liquid chromatography of all 20 phenylthiocarbamyl-amino acids has provided quantitative analysis at low picomole levels. This efficient and sensitive procedure is particularly useful for examining in vivo excision of protein C-termini and for verifying the integrity of various protein products produced by recombinant DNA techniques.

Amino Acid Sequence↗
PubMed1979

Catalytic role of the metal ion of carboxypeptidase A in ester hydrolysis.

The mechanism of action of bovine pancreatic carboxypeptidase. Aalpha (peptidyl-L-amino acid hydrolase; EC 3.4.12.2) has been investigated by application of cryoenzymologic methods. Kinetic studies of the hydrolysis of the specific ester substrate O-(trans-p-chlorocinnamoyl)-L-beta-phenyllactate have been carried out with both the native and the Co2+-substituted enzyme in the 25 to --45 degrees C temperature range. In the --25 to --45 degrees C temperature range with enzyme in excess, a biphasic reaction is observed for substrate hydrolysis characterized by rate constants for the fast (kf) and the slow (ks) processes. In Arrhenius plots, ks extrapolates to kcat at 25 degrees C for both enzymes in aqueous solution, indicating that the same catalytic rate-limiting step is observed. The slow process is analyzed for both metal enzymes, as previously reported (Makinen, M. W., Yamamura, K., and Kaiser, E. T. (1976) Proc Natl. Acad. Sci. U. S. A. 73, 3882-3886), to involve the deacylation of a mixed anhydride acyl-enzyme intermediate. Near --60 degrees C the acyl-enzyme intermediate of both metal enzymes can be stabilized for spectral characterization. The pH and temperature dependence of ks reveals a catalytic ionizing group with a metal ion-dependent shift in pKa and an enthalpy of ionization of 7.2 kcal/mol for the native enzyme and 6.2 kcal/mol for the Co2+ enzyme. These parameters identify the ionizing catalytic group as the metal-bound water molecule. Extrapolation of the pKa data to 25 degrees C indicates that this ionization coincides with that observed in the acidic limb of the pH profile of log(kcat/Km(app)) for substrate hydrolysis under steady state conditions. The results indicate that in the esterolytic reaction of carboxypeptidase. A deacylation of the mixed anhydride intermediate is catalyzed by a metal-bound hydroxide group.

Animals↗
PubMed1988

The A- and B-chains of carboxypeptidase I from germinated barley originate from a single precursor polypeptide.

Carboxypeptidase I from germinated barley (Hordeum vulgare) grain consists of two peptide chains linked by disulfides; the A- and B-chains contain 266 and 148 amino acid residues, respectively (Sorensen, S. B., Breddam, K., and Svendsen, I. (1986) Carlsberg Res. Commun. 51, 475-485). A cDNA library prepared from mRNA isolated from scutella of 2-day germinated barley has now been screened with a mixed oligonucleotide encoding a peptide fragment of the A-chain. Nucleotide sequence analysis of a 1443-nucleotide pair cDNA clone revealed that both chains of the enzyme are translated from a single mRNA. The coding region of the A-chain is located at the 5'-end of the cDNA and is separated from the B-chain coding region by a 165-nucleotide pair linking region. The B-chain coding region is followed by a stop codon, a 187-nucleotide pair 3'-untranslated sequence, and a short polyadenylic acid tail. The results indicate that the A- and B-chains of barley carboxypeptidase I arise by endoproteolytic excision of a 55-residue linker peptide from a single precursor polypeptide chain. The putative linker peptide is rich in proline, lysine, and arginine residues, has an apparent pI of 11.9, and appears to be excised by cleavage of peptide bonds on the COOH-terminal side of serine residues.

Amino Acid Sequence↗