Structure-function relationships of proteinase inhibitors from soybean (Bowman-Birk) and lima bean
Contributions of tyrosyl residues to trypsin-and chymotrypsin-inhibitory activities in two homologous proteinase inhibitors were investigated by modifying them with N-acetylimidazole under various conditions. The acetylation of Tyr 55 is accompanied by 60% loss in antichymotryptic activity. Deacetylation with hydroxylamine restores the activity to the original level. The acetylation of Tyr 69 parallels decrease in antitryptic activity. The inhibitor acetylated at Tyr 69 is fully active toward chymotrypsin and has 30 to 40% antitryptic activity of the native. The original level of antitryptic activity is restored upon deacetylation. The acetylated only 29% (acetylated without guanidine hydrochloride) and 17% (acetylated with guanidine hydrochloride) of the original antitryptic activity. Deacetylation partially restores the lost antitryptic activity in the inhibitor acetylated without the denaturing agent. The total and irreversible loss of antitryptic activity in samples acetylated in the presence of 8 m urea or 6 m guanidine hydrochloride is attributed to the acetylation at the epsilon-amino group of Lys 26 at the trypsin-inhibitory site.
- Research Organization:
- Univ. of California, Los Angeles
- OSTI ID:
- 5308285
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 254:16; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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