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Interactions of papaya proteinase IV with inhibitors
Author(s) -
Buttle David J.,
Ritonja Anka,
Dando Pamela M.,
Abrahamson Magnus,
Shaw Elliot N.,
Wikstrom Peter,
Turk Vito,
Barrett Alan J.
Publication year - 1990
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(90)80153-a
Subject(s) - papain , proteolysis , cystatin , chemistry , biochemistry , trypsin , enzyme , cysteine proteinase inhibitors , glycine , peptide , cystatin c , amino acid , apoptosis , programmed cell death , renal function , caspase
Papaya proteinase IV (PPIV) is not inhibited by chicken cystatin, or human cystatins A or C, unlike most other proteinases of the papain superfamily. The enzyme inactivates chicken cystatin and human cystatin C by limited proteolysis of the glycyl bond previously shown to be involved in the inhibitory inactivity of the cystatins, but has no action on cystatin A. Contamination of commercial crystalline papain with PPIV accounts for the limited proteolysis of cystatins by ‘papain’ reported previously. PPIV is slowly bound by human α 2 ‐macroglobulin. The enzyme is irreversibly inactivated by E‐64, and by peptidyl diazomethanes containing glycine in P 1 and a hydrophobic side‐chain in P 2 . The reaction of PPIV with iodoacetate is extremely slow. PPIV is inhibited by peptide aldehydes despite the presence of bulky sidechains in P 1 , suggesting that these reversible inhibitors do not bind as substrate analogues.