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gamma. irradiation of Bowman--Birk soybean proteinase inhibitor

Journal Article · · Radiat. Res.; (United States)
DOI:https://doi.org/10.2307/3574607· OSTI ID:7090760
;

Radiation damage to Bowman-Birk soybean proteinase inhibitor was studied in dilute aqueous solutions containing: (a) air, (b) N/sub 2/O plus KBr, and (c) N/sub 2/O plus KCNS. The degradation of tyrosines, monitored by changes in ultraviolet absorption and circular dichroism (CD) spectra of irradiated inhibitor, led to the loss of chymotrypsin-inhibitory activity without affecting antitrypsin activity. Of two tyrosyl residues in the inhibitor, Tyr 45, located next to the antichymotrypsin site, was shown to be essential to chymotrypsin-inhibitory activity. Radiation damage to Tyr 59 had no effect on either of the antiproteinase activities. The loss of trypsin-inhibitory activity paralleled decrease in disulfide Cd. The breakage of disulfide bonds was confirmed by the p-chloromercuribenzoate assay for sulfhydryl groups. However, the exact role of disulfide bonds in antitryptic activity, other than the maintenance of conformational integrity, is not apparent. It seems more likely that the loss of trypsin-inhibitory activity is due to damage in other amino acid(s), although the degradation of tyrosine (2 residues) and histidine (1 residue) did not affect antitryptic activity.

Research Organization:
Univ. of California, Los Angeles
OSTI ID:
7090760
Journal Information:
Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 72:3; ISSN RAREA
Country of Publication:
United States
Language:
English

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Related Subjects

560111* -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINO ACIDS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ENZYME INHIBITORS
ENZYMES
FOOD
GAMMA RADIATION
HYDROLASES
HYDROXY ACIDS
IONIZING RADIATIONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
RADIATION EFFECTS
RADIATIONS
SOYBEANS
SPECTRA
TRYPSIN
TYROSINE
VEGETABLES