Carboxypeptidase B: A ZINC-dependent carboxypeptidase primary found in the DIGESTIVE SYSTEM. The enzyme catalyzes the preferential cleavage of a C-terminal peptidyl-L-lysine or arginine. It was formerly classified as EC and EC Enzymes that act at a free C-terminus of a polypeptide to liberate a single amino acid residue.Carboxypeptidases A: Carboxypeptidases that are primarily found the DIGESTIVE SYSTEM that catalyze the release of C-terminal amino acids. Carboxypeptidases A have little or no activity for hydrolysis of C-terminal ASPARTIC ACID; GLUTAMIC ACID; ARGININE; LYSINE; or PROLINE. This enzyme requires ZINC as a cofactor and was formerly listed as EC and EC H: A ZINC-containing exopeptidase primarily found in SECRETORY VESICLES of endocrine and neuroendocrine cells. It catalyzes the cleavage of C-terminal ARGININE or LYSINE residues from polypeptides and is active in processing precursors of PEPTIDE HORMONES and other bioactive peptides.Lysine Carboxypeptidase: A metallocarboxypeptidase that removes C-terminal basic amino acid from peptides and proteins, with preference shown for lysine over arginine. It is a plasma zinc enzyme that inactivates bradykinin and anaphylatoxins.Carboxypeptidase U: A metallocarboxypeptidase that removes C-terminal lysine and arginine from biologically active peptides and proteins thereby regulating their activity. It is a zinc enzyme with no preference shown for lysine over arginine. Pro-carboxypeptidase U in human plasma is activated by thrombin or plasmin during clotting to form the unstable carboxypeptidase U.Cathepsin A: A carboxypeptidase that catalyzes the release of a C-terminal amino acid with a broad specificity. It also plays a role in the LYSOSOMES by protecting BETA-GALACTOSIDASE and NEURAMINIDASE from degradation. It was formerly classified as EC and EC Precursor of plasmin (FIBRINOLYSIN). It is a single-chain beta-globulin of molecular weight 80-90,000 found mostly in association with fibrinogen in plasma; plasminogen activators change it to fibrinolysin. It is used in wound debriding and has been investigated as a thrombolytic agent.Pancreas: A nodular organ in the ABDOMEN that contains a mixture of ENDOCRINE GLANDS and EXOCRINE GLANDS. The small endocrine portion consists of the ISLETS OF LANGERHANS secreting a number of hormones into the blood stream. The large exocrine portion (EXOCRINE PANCREAS) is a compound acinar gland that secretes several digestive enzymes into the pancreatic ductal system that empties into the DUODENUM.Glutamate Carboxypeptidase II: A metallocarboxypeptidase that is predominantly expressed as a membrane-bound enzyme. It catalyzes the hydrolysis of an unsubstituted, C-terminal glutamyl residue, typically from PTEROYLPOLYGLUTAMIC ACIDS. It was formerly classified as EC A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC A product of the lysis of plasminogen (profibrinolysin) by PLASMINOGEN activators. It is composed of two polypeptide chains, light (B) and heavy (A), with a molecular weight of 75,000. It is the major proteolytic enzyme involved in blood clot retraction or the lysis of fibrin and quickly inactivated by antiplasmins.Enzyme Precursors: Physiologically inactive substances that can be converted to active enzymes.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Chymotrypsin: A serine endopeptidase secreted by the pancreas as its zymogen, CHYMOTRYPSINOGEN and carried in the pancreatic juice to the duodenum where it is activated by TRYPSIN. It selectively cleaves aromatic amino acids on the carboxyl side.Fibrinolysis: The natural enzymatic dissolution of FIBRIN.Kinetics: The rate dynamics in chemical or physical systems.Pancreatitis: INFLAMMATION of the PANCREAS. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of CHRONIC PANCREATITIS (International Symposium on Acute Pancreatitis, Atlanta, 1992). The two most common forms of acute pancreatitis are ALCOHOLIC PANCREATITIS and gallstone pancreatitis.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.gamma-Glutamyl Hydrolase: Catalyzes the hydrolysis of pteroylpolyglutamic acids in gamma linkage to pterolylmonoglutamic acid and free glutamic acid. EC Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Chromatography, Affinity: A chromatographic technique that utilizes the ability of biological molecules to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Molecular Weight: The sum of the weight of all the atoms in a molecule.Micromonosporaceae: A family of gram-positive, saprophytic bacteria occurring in soil and aquatic environments.Thermoactinomyces: A genus of gram-positive bacteria in the family Thermoactinomycetaceae, that can cause FARMER'S LUNG.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Micromonospora: A genus of gram-positive bacteria that forms a branched mycelium. It commonly occurs as a saprophytic form in soil and aquatic environments.Serine-Type D-Ala-D-Ala Carboxypeptidase: A carboxypeptidase that is specific for proteins that contain two ALANINE residues on their C-terminal. Enzymes in this class play an important role in bacterial CELL WALL biosynthesis.Streptomyces: A genus of bacteria that form a nonfragmented aerial mycelium. Many species have been identified with some being pathogenic. This genus is responsible for producing a majority of the ANTI-BACTERIAL AGENTS of practical value.Peptidyl-Dipeptidase A: A peptidyl-dipeptidase that catalyzes the release of a C-terminal dipeptide, -Xaa-*-Xbb-Xcc, when neither Xaa nor Xbb is Pro. It is a Cl(-)-dependent, zinc glycoprotein that is generally membrane-bound and active at neutral pH. It may also have endopeptidase activity on some substrates. (From Enzyme Nomenclature, 1992) EC A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.Dipeptidyl Peptidase 4: A serine protease that catalyses the release of an N-terminal dipeptide. Several biologically-active peptides have been identified as dipeptidyl peptidase 4 substrates including INCRETINS; NEUROPEPTIDES; and CHEMOKINES. The protein is also found bound to ADENOSINE DEAMINASE on the T-CELL surface and is believed to play a role in T-cell activation.Ethyl Methanesulfonate: An antineoplastic agent with alkylating properties. It also acts as a mutagen by damaging DNA and is used experimentally for that effect.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Dictionaries, MedicalDictionaries as Topic: Lists of words, usually in alphabetical order, giving information about form, pronunciation, etymology, grammar, and meaning.Protein O-Methyltransferase: An enzyme that catalyzes the transfer of methyl groups from S-adenosylmethionine to free carboxyl groups of a protein molecule forming methyl esters. EC 2.1.1.-.Protein Footprinting: A method for determining points of contact between interacting proteins or binding sites of proteins to nucleic acids. Protein footprinting utilizes a protein cutting reagent or protease. Protein cleavage is inhibited where the proteins, or nucleic acids and protein, contact each other. After completion of the cutting reaction, the remaining peptide fragments are analyzed by electrophoresis.Epitope Mapping: Methods used for studying the interactions of antibodies with specific regions of protein antigens. Important applications of epitope mapping are found within the area of immunochemistry.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Books, Illustrated: Books containing photographs, prints, drawings, portraits, plates, diagrams, facsimiles, maps, tables, or other representations or systematic arrangement of data designed to elucidate or decorate its contents. (From The ALA Glossary of Library and Information Science, 1983, p114)Abstracting and Indexing as Topic: Activities performed to identify concepts and aspects of published information and research reports.Antibodies: Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).Antibody Specificity: The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Antibodies, Viral: Immunoglobulins produced in response to VIRAL ANTIGENS.

Mapping the pro-region of carboxypeptidase B by protein engineering. Cloning, overexpression, and mutagenesis of the porcine proenzyme. (1/124)

The proteolytic processing of pancreatic procarboxypeptidase B to a mature and functional enzyme is much faster than that of procarboxypeptidase A1. This different behavior has been proposed to depend on specific conformational features at the region that connects the globular domain of the pro-segment to the enzyme and at the contacting surfaces on both moieties. A cDNA coding for porcine procarboxypeptidase B was cloned, sequenced, and expressed at high yield (250 mg/liter) in the methylotrophic yeast Pichia pastoris. To test the previous hypothesis, different mutants of the pro-segment at the putative tryptic targets in its connecting region and at some of the residues contacting the active enzyme were obtained. Moreover, the complete connecting region was replaced by the homologous sequence in procarboxypeptidase A1. The detailed study of the tryptic processing of the mutants shows that limited proteolysis of procarboxypeptidase B is a very specific process, as Arg-95 is the only residue accessible to tryptic attack in the proenzyme. A fast destabilization of the connecting region after the first tryptic cut allows subsequent proteolytic processing and the expression of carboxypeptidase B activity. Although all pancreatic procarboxypeptidases have a preformed active site, only the A forms show intrinsic activity. Mutational substitution of Asp-41 in the globular activation domain, located at the interface with the enzyme moiety, as well as removal of the adjacent 310 helix allow the appearance of residual activity in the mutated procarboxypeptidase B, indicating that the interaction of both structural elements with the enzyme moiety prevents the binding of substrates and promotes enzyme inhibition. In addition, the poor heterologous expression of such mutants indicates that the mutated region is important for the folding of the whole proenzyme.  (+info)

An integrated study of fibrinogen during blood coagulation. (2/124)

The rate of conversion of fibrinogen (Fg) to the insoluble product fibrin (Fn) is a key factor in hemostasis. We have developed methods to quantitate fibrinopeptides (FPs) and soluble and insoluble Fg/Fn products during the tissue factor induced clotting of whole blood. Significant FPA generation (>50%) occurs prior to visible clotting (4 +/- 0.2 min) coincident with factor XIII activation. At this time Fg is mostly in solution along with high molecular weight cross-linked products. Cross-linking of gamma-chains is virtually complete (5 min) prior to the release of FPB, a process that does not occur until after clot formation. FPB is detected still attached to the beta-chain throughout the time course demonstrating release of only low levels of FPB from the clot. After release of FPB a carboxypeptidase-B-like enzyme removes the carboxyl-terminal arginine resulting exclusively in des-Arg FPB by the 20-min time point. This process is inhibited by epsilon-aminocaproic acid. These results demonstrate that transglutaminase and carboxypeptidase enzymes are activated simultaneously with Fn formation. The initial clot is a composite of Fn I and Fg already displaying gamma-gamma cross-linking prior to the formation of Fn II with Bbeta-chain remaining mostly intact followed by the selective degradation of FPB to des-Arg FPB.  (+info)

Enzymic characterization of a novel member of the regulatory B-like carboxypeptidase with transcriptional repression function: stimulation of enzymic activity by its target DNA. (3/124)

The adipocyte-enhancer binding protein (AEBP) 1 is a novel transcriptional repressor with carboxypeptidase (CP) activity. AEBP1 binds to a regulatory sequence (termed adipocyte enhancer 1, AE-1) located in the proximal promoter region of the adipose P2 (aP2) gene, which encodes the adipocyte fatty-acid binding protein. Sequence comparisons and kinetic studies using known carboxypeptidase substrates, activators and inhibitors have characterized AEBP1 as a member of the regulatory B-like CP family. Significantly, the inherent CP activity of AEBP1 is stimulated by the AE-1 sequence. Our results indicate that AEBP1 is activated by a novel mechanism, wherby the direct binding of DNA enhances its protease activity. These results represent the first demonstration of DNA-mediated regulation of CP activity.  (+info)

Characterization of plasmin-mediated activation of plasma procarboxypeptidase B. Modulation by glycosaminoglycans. (4/124)

Plasma carboxypeptidase B (PCB) is an exopeptidase that exerts an antifibrinolytic effect by releasing C-terminal Lys and Arg residues from partially degraded fibrin. PCB is produced in plasma via limited proteolysis of the zymogen, pro-PCB. In this report, we show that the K(m) (55 nM) for plasmin-catalyzed activation of pro-PCB is similar to the plasma concentration of pro-PCB (50-70 nM), whereas the K(m) for the thrombin- or thrombin:thrombomodulin-catalyzed reaction is 10-40-fold higher than the pro-PCB level in plasma. Additionally, tissue-type plasminogen activator triggers activation of pro-PCB in blood plasma in a reaction that is stimulated by a neutralizing antibody versus alpha(2)-antiplasmin. Together, these results show that plasmin-mediated activation of pro-PCB can occur in blood plasma. Heparin (UH) and other anionic glycosaminoglycans stimulate pro-PCB activation by plasmin but not by thrombin or thrombin:thrombomodulin. Pro-PCB is a more favorable substrate for plasmin in the presence of UH (16-fold increase in k(cat)/K(m)). UH also stabilizes PCB against spontaneous inactivation. The presence of UH in clots prepared with prothrombin-deficient plasma delays tissue-type plasminogen activator-triggered lysis; this effect of UH on clot lysis is blocked by a PCB inhibitor from potato tubers. These results show that UH accelerates plasmin-catalyzed activation of pro-PCB in plasma and PCB, in turn, stabilizes fibrin against fibrinolysis. We propose that glycosaminoglycans in the subendothelial extracellular matrix serve to augment the levels of PCB activity thereby stabilizing blood clots at sites where there is a breach in the integrity of the vasculature.  (+info)

Detection of small-molecule enzyme inhibitors with peptides isolated from phage-displayed combinatorial peptide libraries. (5/124)

BACKGROUND: The rapidly expanding list of pharmacologically important targets has highlighted the need for ways to discover new inhibitors that are independent of functional assays. We have utilized peptides to detect inhibitors of protein function. We hypothesized that most peptide ligands identified by phage display would bind to regions of biological interaction in target proteins and that these peptides could be used as sensitive probes for detecting low molecular weight inhibitors that bind to these sites. RESULTS: We selected a broad range of enzymes as targets for phage display and isolated a series of peptides that bound specifically to each target. Peptide ligands for each target contained similar amino acid sequences and competition analysis indicated that they bound one or two sites per target. Of 17 peptides tested, 13 were found to be specific inhibitors of enzyme function. Finally, we used two peptides specific for Haemophilus influenzae tyrosyl-tRNA synthetase to show that a simple binding assay can be used to detect small-molecule inhibitors with potencies in the micromolar to nanomolar range. CONCLUSIONS: Peptidic surrogate ligands identified using phage display are preferentially targeted to a limited number of sites that inhibit enzyme function. These peptides can be utilized in a binding assay as a rapid and sensitive method to detect small-molecule inhibitors of target protein function. The binding assay can be used with a variety of detection systems and is readily adaptable to automation, making this platform ideal for high-throughput screening of compound libraries for drug discovery.  (+info)

Effect of the reaction field electrostatic term on the molecular dynamics simulation of the activation domain of procarboxypeptidase B. (6/124)

Molecular dynamics simulations of the activation domain of porcine procarboxypeptidase B (ADBp) were performed in order to examine the effects of the inclusion of a reaction field (RF) term into the calculation of electrostatics forces for highly charged proteins. Two simulations were performed with the GROMOS96 package, studying the influence of counterions on the final results. Comparison with previous results without the inclusion of the RF term (Marti-Renom, M.A., Mas,J.M., Oliva,B., Querol,E. and Aviles,F.X., Protein Engng, 1998, 11, 101-110) shows that the structure is well maintained when the RF term is included. Moreover, the analysis of the trajectories shows that simulations of solvated highly-charged proteins are sensitive to the presence of counterions, the secondary structures being more stable when their charges are neutralized.  (+info)

Acute, nontoxic cadmium exposure inhibits pancreatic protease activities in the mouse. (7/124)

Toxic effects of cadmium on liver, kidney, lung, and testes have been well established in experimental animals and in cell model systems. However, little is known about the effect of cadmium on pancreas, though the pancreas has been reported to accumulate high concentrations of cadmium. Therefore, in this study we examined the effects of cadmium on the pancreas of mice. A single sc injection of 1 mg Cd/kg to mice had no obvious toxic effects on the liver, kidney, and pancreas at both 1 and 5 days after cadmium treatment. Within the pancreas, however, the activities of trypsin, chymotrypsin, and carboxypeptidase A were significantly decreased at 1 day after cadmium treatment, whereas the activity of carboxypeptidase B was not changed. All pancreatic enzyme activities returned to the control levels by 5 days after cadmium treatment. The concentrations of cadmium in pancreas were very similar at 1 and 5 days after cadmium treatment, indicating a stable deposition of the metal. The concentration of zinc in pancreas was markedly increased at 5 days after cadmium treatment. In order to more fully examine the inhibitory effects of cadmium on these protease activities in pancreas, the direct effects of cadmium on purified proteases were studied in vitro. Contrary to the results in vivo, cadmium increased the activity of purified trypsin in a concentration-dependent manner. Consistent with the in vivo results, the activity of purified carboxypeptidase A was decreased by cadmium treatment in a concentration-dependent fashion in vitro. The activities of chymotrypsin and carboxypeptidase B did not change by the cadmium exposure in vitro. The enhanced activity of trypsin by cadmium was returned to the control levels by subsequent treatment with EDTA, indicating that enhancement was reversible. In addition, the zinc normally contained in purified carboxypeptidase A and carboxypeptidase B was released by the cadmium treatment. These results indicate that cadmium inhibits protease activities within the pancreas in vivo at doses that do not induce overt hepatic, renal, or pancreatic toxicity. Based on in vitro study, the decreases seen in trypsin and chymotrypsin activities might be based on indirect effects of cadmium, whereas the decreases in carboxypeptidase A are probably due to the direct inhibition by the metal.  (+info)

Thrombin-activable fibrinolysis inhibitor attenuates (DD)E-mediated stimulation of plasminogen activation by reducing the affinity of (DD)E for tissue plasminogen activator. A potential mechanism for enhancing the fibrin specificity of tissue plasminogen activator. (8/124)

A complex of d-dimer noncovalently associated with fragment E ((DD)E), a degradation product of cross-linked fibrin that binds tissue plasminogen activator (t-PA) and plasminogen (Pg) with affinities similar to those of fibrin, compromises the fibrin specificity of t-PA by stimulating systemic Pg activation. In this study, we examined the effect of thrombin-activable fibrinolysis inhibitor (TAFI), a latent carboxypeptidase B (CPB)-like enzyme, on the stimulatory activity of (DD)E. Incubation of (DD)E with activated TAFI (TAFIa) or CPB (a) produces a 96% reduction in the capacity of (DD)E to stimulate t-PA-mediated activation of Glu- or Lys-Pg by reducing k(cat) and increasing K(m) for the reaction; (b) induces the release of 8 mol of lysine/mol of (DD)E, although most of the stimulatory activity is lost after release of only 4 mol of lysine/mol (DD)E; and (c) reduces the affinity of (DD)E for Glu-Pg, Lys-Pg, and t-PA by 2-, 4-, and 160-fold, respectively. Because TAFIa- or CPB-exposed (DD)E produces little stimulation of Glu-Pg activation by t-PA, (DD)E is not degraded into fragment E and d-dimer, the latter of which has been reported to impair fibrin polymerization. These data suggest a novel role for TAFIa. By attenuating systemic Pg activation by (DD)E, TAFIa renders t-PA more fibrin-specific.  (+info)

Preferential cleavage:
  • The activation process of porcine pancreatic procarboxypeptidase B (pro‐CPB) has been studied in detail by a number of complementary methodologies, and a description of the molecular events that lead to the generation of active carboxypeptidase B (CPB) has been deduced. (
  • Expression of carboxypeptidase M on mRNA level and enzymatic activity markedly increase during in vitro differentiation of monocytes, according to the described increase in MAX.1 and MAX.11 antigen expression. (
  • In addition to providing information about the specific role of this exopeptidase in E. coli, the Dep- mutants may prove useful for delineating the regulation and cellular function of dipeptidyl carboxypeptidases in higher organisms. (
  • Sun L, Guo C, Burnett J, Pan J, Yang Z, Ran Y, Sun D. Association between expression of Carboxypeptidase 4 and stem cell markers and their clinical significance in liver cancer development. (
  • This study aimed to evaluate the expression of carboxypeptidase 4 (CPA4) in hepatitis, liver cirrhosis and liver cancer tissues, and revealed its clinical significance in liver cancer progression. (
  • The fact that two of the least related proteins within this clade are acyltransferases rather than true serine carboxypeptidases suggests that some or all of the remaining members of this group may have similar activities. (

Xaa = any amino acid residue
↓ = cleavage site
XaaXaaXaaXaaXaaXaanot Ser