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Pig leukocyte cysteine proteinase inhibitor (PLCPI), a new member of the stefin family
Author(s) -
Lenarc̆ic̆ Brigita,
Ritonja Anka,
Dolenc Iztok,
Stoka Veronika,
Berbic̆ Selma,
Pungerc̆ar Joz̆e,
Štrukelj Borut,
Turk Vito
Publication year - 1993
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(93)80822-c
Subject(s) - papain , cysteine , cysteine proteinase inhibitors , biochemistry , chemistry , enzyme , proteinase inhibitor , microbiology and biotechnology , serine , amino acid , peptide sequence , enzyme inhibitor , cathepsin , biology , apoptosis , programmed cell death , caspase , gene
A new stefin type low‐ M r , cysteine proteinase inhibitor (PLCPI) was isolated from pig polymorphonuclear leukocytes as a contaminant of the cathelin sample. The inhibitor consists of 103 amino acids, and its M r , was calculated to be 11,768. The inhibitor exhibits considerable sequence identity with inhibitors from the stefin family, particularly with human stefin A. The PLCPI is a fast acting inhibitor of papain and cathepsins L and S ( k ass ⩾ 1 × 10 6 M −1 · s −1 ) and forms very tight complexes with these enzymes ( K i , ⩽ 190 pM). The affinity for cathepsins B and H ( K i ⩾ 125 nM) was lower. These results also show that the inhibitory activity previously ascribed to cathelin was due to the presence of PLCPI.