Carboxypeptidase A inhibitor

Osciiiamides- protein phosphatase (1 and 2A) inhibitors 14, 113 Anabaenopeptins G and H - carboxypeptidase A inhibitors 114... 

G. A. Arteca, O. Tapia, and P. G. Mezey,/. Mol. Graphics, 9, 148 (1991). Implementing Knot-Theoretical Characterization Methods to Analyze the Backbone Structure of Proteins Application to CTF-L7/L12 and Carboxypeptidase A Inhibitor Protein. 

This analysis reveals that enzymes bind the transition state more tightly than the ground state by a factor approximately equal to the rate of acceleration (ie, Kjs/Ks kuncaJkcat)- This method has been used to show, for example, that the peptide phos-phonate inhibitors of carboxypeptidase A are true transition state analogs. 

Peptidyl-dipeptidase A (angiotensin-I converting enzyme, ACE, EC 3.4.15.1) plays a pivotal role in the control of blood pressure [80]. It has been established that its active site contains an essential Zn-atom that functions like that of carboxypeptidase A [2], ACE is inhibited by peptides having a proline or aromatic amino acid at the C-terminal position. These observations as well as the similarities with the active site of carboxypeptidase A have allowed a rational design of effective inhibitors of ACE (e.g., captopril (3.4) and enalapril (3.5)) used in the treatment of hypertension [81]. 

The enzyme carboxypeptidase A is particularly amenable to structural investigation crystal structures of the enzyme, of complexes of the enzyme with substrates, substrate analogues and inhibitors, and of transition-state analogues are available. To isolate an enzyme-substrate complex for a one-substrate enzyme reaction, or for an enzyme reaction where water is a... 

A novel concept of using bioadhesive polymers as enzyme inhibitors has been developed [97]. Included are derivatives of poly acrylic acid, polycarbophil, and car-bomer to protect therapeutically important proteins and peptides from proteolytic activity of enzymes, endopeptidases (trypsin and a-chymotrypsin), exopeptidases (carboxypeptidases A and B), and microsomal and cytosolic leucine aminopeptidase. However, cysteine protease (pyroglutamyl aminopeptidase) is not inhibited by polycarbophil and carbomer [97]. 

The stereochemistry of anion-zinc interactions is important as inhibitors interact with the active site of carboxypeptidase A. For instance. 

Fig. 34. Glu-72- Zn interactions in native carboxypeptidase A and in carboxypep-tidase A-inhibitor complexes (inhibitors have been reviewed by Christianson and Lipscomb, 1989). When substrates or inhibitors bind to the enzyme active site and interact with the zinc ion, the interaction of the metal with Glu-72 tends from bidentate toward uniden-tate coordination. The flexibility of protein-zinc coordination may be an important aspect of catalysis in this system, and the Glu-72->Zn - coordination stereochemistry observed here is consistent with the stereochemical analysis of carboxylate-zinc interactions from the Cambridge Structural Database (Carrell et al., 1988 see Fig. 4).

P. A. Bartlett, Phosphonate analogs of carboxypeptidase A substrates are potent transition-state analog inhibitors, Biochemistry, 1989, 28, 6294—305. 

Aprotinin is a polypeptide consisting of 58 amino acid residues derived from bovine lung tissues and shows inhibitory activity toward various proteolytic enzymes including chymo-trypsin, kallikrein, plasmin, and trypsin. It was also one of the first enzyme inhibitors used as an auxiliary agent for oral (poly)peptide administration. The co-administration of aprotinin led to an increased bioavailability of peptide and protein drugs [5,44,45], The Bowman-Birk inhibitor (71 amino acids, 8 kDa) and the Kunitz trypsin inhibitor (184 amino acids, 21 kDa) belong to the soybean trypsin inhibitors. Both are known to inhibit trypsin, chymotrypsin, and elastase, whereas carboxypeptidase A and B cannot be inhibited [7,46],... 

Stable compounds which resemble the transition-state structure of a substrate in an enzymatic reaction are expected to behave as potent reversible inhibitors (1 ). Based on the X-ray crystallographic structure of the active site of carboxypeptidase A (CPA) (2), a mechanism was proposed in which a water molecule adds directly to the scissile carbonyl group of the substrate to give the tetrahedral intermediate 1, which collapses to products (3). We proposed to mimic this tetrahedral intermediate, similar to the transition state, with the stable tetrahedral phosphonic acid derivatives 2,... 

Competitive inhibition of the carboxypeptidase from A. saitoi by small substrates was found with hydrocinnamic acid, indole-3-propionic acid, and 4-phenylbutyric acid [80], The K for hydrocinnamic acid inhibition was 4 x 10 4 M. Diisopropylfluorophosphate (DFP) and tosyl-L-phenylalanylchloromethane (TPCK) were also powerful inhibitors of the carboxypeptidase from A. oryzae (80). />-Chloromercuribenzoate (PCMB) and iodoacetic acid were also powerful inhibitors of the carboxypeptidase from A. saitoi, while the inhibitors of DFP, TPCK, PCMB, and iodoacetic acid on the carboxypeptidase from A. saitoi were less than that of A. oryzae [80], As the carboxypeptidase activity of A. saitoi has no effect when used with ethylenediaminetetraacetate (EDTA) and o-phenanthroline, the enzyme is a different type of carboxypeptidase from those of the pancreatic sources, carboxypeptidase A and carboxypeptidase B [80],... 

In their early efforts to apply the by-product design to ACE, Patchett and Maycock had synthesized only succinylproline, based on the findings of Byers and Wolfenden that benzylsuccinate was superior to ben-zylglutamate as an inhibitor of carboxypeptidase A. Similar active site topologies were assumed for these two enzymes. Evidently this was not the case, since Cushman et al. reported in 1977 (96) that glutarylpro-line (compound 6 Table II.) was more active than compound 5 (Table... 

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