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Exploring the binding preferences/specificity in the active site of human cathepsin E
Author(s) -
RaoNaik Chetana,
Guruprasad Kunchur,
Batley Brian,
Rapundalo Stephen,
Hill Jeffrey,
Blundell Tom,
Kay John,
Dunn Ben M.
Publication year - 1995
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340220209
Subject(s) - cathepsin o , cathepsin a , biochemistry , cathepsin d , cathepsin l1 , cathepsin e , chemistry , enzyme , exopeptidase , cathepsin h , peptide , cathepsin
Aspartic proteinases are produced in the human body by a variety of cells. Some of these proteins, examples of which are pepsin, gastricsin, and renin, are secreted and exert their effects in the extracellular spaces. Cathepsin D and cathepsin E on the other hand are intracellular enzymes. The least characterized of the human aspartic proteinases is cathepsin E. Presented here are results of studies designed to characterize the binding specificities in the active site of human cathepsin E with comparison to othermechanistically similar enzymes. A peptide series based on Lys‐Pro‐Ala‐Lys‐Phe*Nph‐Arg‐Leu was generatedto elucidate the specificity in the individual binding pockets with systematic substitutions in the P 5− P 2 and P 2 ′‐P 3 ′ based on charge, hydrophobicity, and hydrogen bonding. Also, to explore the S 2 binding preferences, asecond series of peptides based on Lys‐Pro‐Ile‐Glu‐Phe*Nph‐Arg‐Leu was generated with systematic replacements in the P 2 position. Kinetic parameters were determined forboth sets of peptides. The results were correlated to a rule‐based structural model of human cathepsin E, constructed on the known three‐dimensional structures of several highly homologous aspartic proteinases; porcine pepsin, bovine chymosin, yeast proteinase A, human cathepsin D, andmouse and human renin. Important specificity‐determining interactions were found in the S 3 (Glu13) and S 2 (Thr‐222, Gln‐287, Leu‐289, Ile‐300)subsites. © 1995 Wiley‐Liss, Inc.