Prolidases

Cheng, T.-C. and DeFrank, J.J. (2000) Hydrolysis of Organophosphorus Compounds by Bacterial Prolidases, in Enzymes in Action Green Solutions for Chemical Problems (eds... 

E2. Endo, F., Tanoue, A., Nakai, H Hata, A., Indo, Y., Titani, K., and Matsuda, I., Primary structure and gene localization of human prolidase. J. Biol. Chem. 264,4476-4481 (1989). 

Non-corrin cobalt has a number of interesting applications in the chemical industry, for example in the hydroformylation (OXO) reaction between CO, H2 and olefins. A number of non-corrin Co-containing enzymes have been described, including methionine aminopep-tidase, prolidase, nitrile hydratase and glucose isomerase. We describe the best characterized of these, namely the E. coli methionine aminopeptidase, a ubiquitous enzyme, which cleaves N-terminal methionine from newly translated polypeptide chains. The active site of the enzyme (Figure 15.13) contains two Co(II) ions that are coordinated by the side-chain atoms of five amino acid residues. The distance between the two Co2+ is similar to that between the two Zn2+ atoms in leucine aminopeptidase, and indeed the catalytic mechanism of methionine aminopeptidase shares many features with other metalloproteases, in particular leucine aminopeptidases. 

Increased permeability is just one prerequisite in the development of useful peptide prodrugs. Another condition is that efficient bioactivation must follow absorption. Mucosal cell enzymes able to hydrolyze peptides include exopeptidases such as aminopeptidases and carboxypeptidases, endopepti-dases, and dipeptidases such as cytosolic nonspecific dipeptidase (EC 3.4.13.18), Pro-X dipeptidase (prolinase, EC 3.4.13.4), and X-Pro dipeptidase (prolidase, EC 3.4.13.9). For example, L-a-methyldopa-Pro was shown to be a good substrate for both the peptide transporter and prolidase. This dual affinity is not shared by all dipeptide derivatives, and, indeed, dipeptides that lack an N-terminal a-amino group are substrates for the peptide transporter but not for prolidase [29] [33] [34],... 

This manganese-dependent enzyme [EC 3.4.13.9] (also known as Xaa—Pro dipeptidase, X—Pro dipeptidase, imidodipeptidase, prolidase, peptidase D, and y-pepti-dase) catalyzes the hydrolysis of Xaa—Pro dipeptides (except for prolylproline). The dipeptidase also acts on aminoacylhydroxyproline derivatives. This cytosolic enzyme, a member of the peptidase family M24A, is found in most animal tissues. 

The AAA thus has two photometers in series. Since for every eluting amino acid both signals are recorded, the so-called 570/440 absorbance ratio may be of help in the identification process. As an example the simple primary amino acids have a 570/440 ratio of approximately 6, whereas the sulfur amino acids (cystine, sulfocysteine) have much lower ratios, approaching a value of 1. Small peptides and glycyl-amino acids will react with ninhydrin, an important fact for the diagnosis of prolidase deficiency and aspartylglycosaminuria. 

Figure 10.22 Schematic representation of the hydrolysis of casein (a) by lactococcal cell envelope proteinase (CEP), and (b) degradation of an hypothetical dodecapeptide by the combined action of lactococcal peptidases oligopeptidase (PepO), various aminopeptidases (PCP, PepN, PepA, PepX), tripeptidase (TRP), prolidase (PRD) and dipeptidase (DIP).

Chrzanowski, K., Bielawska, A., and Palka, J. Proline analogue of melphalan as prodrug susceptible to the action of prolidase in breast cancer MDA-MB 231 cells. 11 Farmaco 58 1113-1119, 2003. 

Bielawska, A., Bielawska, K., Chrzanowski, K., and Wolczynski, S. Prolidase-activated prodrug for cancer chemotherapy cytotoxic activity of praline analogue of chlorambucil in breast cancer MCF-7 cells. II Farmaco 55 736-741, 2000. 

Such isopeptides also have been found naturally present in keratin (77,78,85) and in polymerized fibrin (79). Their quantitative determination requires an enzymic hydrolysis using pepsin, pronase, amino-peptidase, and prolidase as described by Cole et al. (135) followed by a chromatographic separation using an amino acid analyzer under very specific conditions (80). 

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