Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.16.2 (PCP)
 3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Through a series of kinetic studies involving the inactivation effects of diisopropylfluorophosphate, an affinity label that modifies the active site serine residue involved in the mechanism of action, it has been firmly established that carboxypeptidase P (CPP) requires a serine residue for catalytic activity. The essential kinetic parameters were determined to be 1.33 mM for the apparent dissociation constant with a limiting half-life of inactivation of 20.1 min. Structural elucidation of the primary amino acid sequence surrounding the essential serine, and comparing that with the reactive site of carboxypeptidase Y (CPY), revealed a significant degree of homology at the active site between these two enzymes. These regions, however, were quite divergent from other known serine proteases, leading to the speculation that these serine exopeptidases may comprise a unique family in the overall classification of serine proteases. It was established that CPY could be inactivated with either of the classic histidine affinity labels tosylphenylalanylchloromethyl ketone (TPCK) or carbobenzoxyphenylalanylchloromethyl ketone (ZPCK) with Ki's of 1.2 and 12.8 microM, respectively. This is in marked contrast to CPP, which was unaffected by saturating levels of the known histidine affinity labels, TPCK, tosyllysylchloromethyl ketone, or ZPCK. This point may be a significant element in differentiating specificity among these two serine proteases. Further investigation into the structural nature of CPP revealed that it is a glycoprotein with a single site of carbohydrate attachment. In addition, the carbohydrate moiety itself appears to contribute 1217 Da to the overall molecular weight and it is characterized as an asparagine linked high mannose type. This is significantly different from CPY with its four sites of carbohydrate attachment contributing approximately 17% to its molecular weight.
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PMID:Structural determination of the essential serine and glycosylation sites of carboxypeptidase P. 157 19

The activity of prolylcarboxypeptidase (PCP), or angiotensinase C, was measured in lung tissues, leukocytes, and cultured human cells using Cbz-Pro-[14C]Ala as a substrate. A lysosomal fraction of homogenized rat or human lung contained most of the PCP activity in that tissue. Polymorphonuclear neutrophils, macrophages, and lymphocytes isolated from human blood had PCP activity. Fibroblasts cultured from human tissues had the highest activity (0.56-1.15 mumol/h per 10(6) cells), more than endothelial cells cultured from human pulmonary arteries. PCP of cultured human fibroblasts was similar to the human renal enzyme because it was resistant to moderate heating and was not inhibited by p-chloromercuriphenyl sulfonic acid. These properties and the substrate specificity distinguish PCP from cathepsin A, which is also in fibroblasts. Antibody to human renal PCP reacted with fibroblast PCP in immunofluorescence, indicating common antigenic determinants. Hydrocortisone changed PCP activity in fibroblasts in parallel with changes in beta-glucuronidase activity and cell-protein concentration; the activity was depressed at low concentration of the hormone. PCP activity was also found in synovial fluid from arthritic joints and in fibroblasts from the synovium. That PCP is found in both inflammatory exudates and in cells that appear at sites of inflammation indicates that, in addition to inactivating angiotensins, this enzyme may have a role in inflammation.
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PMID:Prolylcarboxypeptidase (angiotensinase C) in human lung and cultured cells. 745 50

This article focuses on four human carboxypeptidases (CPs): two metallo-CPs and two serine CPs. The metallo-CPs are members of the so-called B-type regulatory CP family, as they cleave only the C-terminal basic amino acids Arg or Lys. The plasma membrane-bound CPM and the mainly, but not exclusively, intracellular CPD are surveyed from this group of enzymes. These enzymes can regulate peptide hormone activity at the cell surface and possibly intracellularly after receptor-mediated endocytosis and may also participate in peptide hormone processing. The serine CPs, as their name indicates, contain a serine residue in the active center essential for catalytic activity that reacts with organophosphorus inhibitors. Prolylcarboxypeptidase (PRCP) (angiotensinase C) and deamidase (cathepsin A, lysosomal protective protein) are discussed here. These two enzymes are highly concentrated in lysosomes; however, they may also be active extracellularly after their release from lysosomes in soluble form or in a plasma membrane-bound complex. Whereas deamidase cleaves a variety of peptides with C-terminal or penultimate hydrophobic residues (e.g. substance P, angiotensin I, bradykinin, endothelin, fMet-Leu-Phe). PRCP cleaves only peptides with a penultimate Pro residue (e.g. des-Arg9-bradykinin, angiotensin II). These enzymes may also be involved in terminating signal transduction by inactivating peptide ligands after receptor endocytosis.
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PMID:Cellular carboxypeptidases. 955 70

In the present study, HPLC-ESI-IT (ion-trap) MS was used for carboxyterminal (C-terminal) amino acid sequence confirmation of intact recombinant Hirudin Variant 3 (HV3) and alkylated HV3. The C-terminal amino acid sequence of HV3 was determined by the use of carboxypeptidase P (CPP), and by the combined use of carboxypeptidase P and carboxypeptidase Y (CPY). The C-terminal amino acid sequence of alkylated HV3 with 1,4-dithiothreitol (DTT) reduction was also confirmed by the combined use of CPP and CPY (abbreviated to CPP-CPY). Up to 19 amino acid residues were confirmed in the nanomolar concentration range by analyzing the molecular weights of the truncated peptides of HV3. Another five amino acids were confirmed in the nanomolar concentration range of alkylated HV3 with DTT reduction. For sequencing alkylated HV3 with DTT reduction, HV3 reduced with DTT followed by alkylation with iodoacetamide. The reaction mixture, which included alkylated HV3, DTT, and iodoacetamide, was then directly sequenced without any further pre-treatment. The reaction was designed in a time-, and concentration-dependent manner to obtain the maximum sequence information. The results showed that HPLC-ESI-ITMS cannot only determine the C-terminal amino acid sequence of HV3, but also gives important information about the enzymatic degradation and subsequent release of the C-terminal amino acids of HV3.
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PMID:Application of HPLC-ESI-ITMS in the quality control of carboxyterminal sequence confirmation for the recombinant DNA product Hirudin Variant 3. 1714 43

Application of HPLC-ESI-ITMS in the quality control of carboxyterminal sequence confirmation for insulin and insulin chain B was studied. The solution of intact insulin or insulin chain B was added to the solution of carboxypeptidase P (CPP) and carboxypeptidase Y (CPY). Fractions of appropriate volume were removed at some appointed time points, acidified with the same amount of 1% formic acid to stop the digestion, and then briefly vortexed for HPLC-ESI-ITMS analysis. Mobile phase A consisted of 0.02% TFA in 98% ultra-pure water and 2% acetonitrile. Mobile phase B consisted of 0.02% TFA in 98% acetonitrile and 2% ultra-pure water. The solution used for post-column fix consisted of propionic acid and isopropyl alcohol (20 : 80, v/v). Chromatographic separation was carried out on a reversed-phase column (Zorbax Prosphere C18, 300A, 5 microm, 2.1 mm ID x 150 mm length). The molecular weights of the multiply charged ions representing consecutive truncated losses of carboxyterminal amino acids were determined by the use of HPLC-ESI-ITMS. The differences between the consecutive truncated peptides are the experimental weights of the carboxyterminal amino acid residues. The carboxyterminal amino acid residue Ala, which released from chain B of intact insulin, was confirmed in the nanomolar concentration range by analyzing the molecular weight of the truncated peptides. Another one carboxyterminal amino acid Ala was confirmed in the nanomolar concentration range of insulin chain B. In the quality control for recombinant DNA product or natural protein, the confirmation of 1 - 3 carboxyterminal amino acid residues is regarded to be up to standard. One amino acid residue of insulin or insulin chain B could be confirmed accurately in the nanomolar concentration range. The results showed that intact insulin could be directly sequenced in the quality control without separating chain B from chain A. There would be no need to separate chain A from chain B to identify carboxyterminal of intact insulin. Furthermore, the method saved us a lot of trouble from the preparation and purification of insulin chain A and chain B.
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PMID:[Application of HPLC-ESI-ITMS in the quality control of carboxyterminal sequence confirmation for insulin and insulin chain B]. 1770 78