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Mechanism of inhibition of papain by chicken egg white cystatin
Author(s) -
Machleidt Werner,
Thiele Ulrich,
Laber Bernd,
Assfalg-Machleidt Irmgard,
Esterl Anna,
Wiegand George,
Kos Janko,
Turk Vito,
Bode Wolfram
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80135-8
Subject(s) - papain , cyanogen bromide , cystatin , chemistry , ovotransferrin , egg white , isoelectric point , biochemistry , microbiology and biotechnology , enzyme , cystatin c , biology , peptide sequence , renal function , gene
N‐terminally truncated forms of chicken egg white cystatin and its cyanogen bromide fragments were isolated and assayed for inhibition of papain. Truncated forms beginning with Gly‐9 and Ala‐10 had a 5000‐fold lower affinity for papain than the two isoelectric forms (p I =6.5 and 5.6) of the full‐length inhibitor ( K i =6 pM and 7 pM) or a truncated form beginning with Leu‐7 ( K i =6 pM), indicating the outstanding importance of one or two residues preceding conserved Gly‐9 for binding. A weak inhibition of papain ( K i =900 nM) was exhibited by the intermediate cyanogen bromide fragment (residues 30–89) containing the chicken cystatin QLVSG variation of the QVVAG segment which is conserved in almost all members of the cystatin superfamily. The obtained affiffity data provide independent evidence for the validity of the proposed docking model of a chicken cystatin‐papain complex [(1988) EMBO J. 7, 2593–2599].