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N‐terminal acetyl group is essential for the inhibitory function of carboxypeptidase Y inhibitor (I C )
Author(s) -
Mima Joji,
Kondo Takahiro,
Hayashi Rikimaru
Publication year - 2002
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/s0014-5793(02)03676-1
Subject(s) - chemistry , circular dichroism , phenylmethylsulfonyl fluoride , carboxypeptidase , stereochemistry , exopeptidase , yeast , escherichia coli , biochemistry , acetylation , amino acid , enzyme , serine , gene
Carboxypeptidase Y (CPY) inhibitor, I C , a yeast cytoplasmic inhibitor in which the N‐terminal amino acid is acetylated, was expressed in Escherichia coli and produced as an unacetylated form of I C (unaI C ). Circular dichroism and fluorescence measurements showed that unaI C and I C were structurally identical and produce identical complexes with CPY. However, the K i values for unaI C for anilidase and peptidase activity of CPY were much larger, by 700‐ and 60‐fold, respectively, than those of I C . The reactivities of phenylmethylsulfonyl fluoride and p ‐chloromercuribenzoic acid toward the CPY–unaI C complex were considerably higher than those toward the CPY–I C complex. Thus, the N‐terminal acetyl group of I C is essential for achieving a tight interaction with CPY and for its complete inactivation.