Lima bean proteinase inhibitor. Origins of circular dichroism bands and modification by Br/sub 2//sup -/ and (CNS)/sub 2//sup -/
Origins of CD bands in lima bean proteinase inhibitor were deduced from an acetylation-deacetylation study of the sole tyrosyl residue in the protein (Tyr 69), and by analogy with Bowman-Birk soybean proteinase inhibitor. A broad negative CD band centered around 280 nm arises mainly from the longest wavelength transition of cystinyl side chains. The second cystinyl transition gives rise to a positive CD band of a comparable intensity at 247 nm. the /sup 1/L/sub b/ vibronic transition of Tyr 69 has negative CD around 280 nm, contributing approximately 10% of the total CD intensity at 278 nm. the 232 nm positive shoulder is from the /sup 1/L/sub a/ vibronic transition of Tyr 69. Radical anions, Br/sub 2//sup -/ and (CNS)/sub 2/, generated by the irradiation of N/sub 2/O-saturated inhibitor solutions containing KBr or KCNS, reduced tyrosyl CD without affecting disulfide CD bands, indicating that the radical anions damaged Tyr 69 without altering protein conformation. The inhibitor modified at Tyr 69 by Br/sub 2//sup -/ and (CNS)/sub 2//sup -/ retained full activity toward trypsin and chymotrypsin. The irradiation of the inhibitor in the air saturated solution led to loss in tyrosyl as well as cystinl CD bands and decline in both antiproteinase activities.
- Research Organization:
- Univ. of California, Los Angeles
- DOE Contract Number:
- EY-76-C-03-0012
- OSTI ID:
- 5376549
- 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
Similar Records
gamma. irradiation of Bowman--Birk soybean proteinase inhibitor
Structure-function relationships of proteinase inhibitors from soybean (Bowman-Birk) and lima bean
Related Subjects
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
560111 -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOCHEMISTRY
BROMINE
CARBONIC ACID DERIVATIVES
CHEMICAL RADIATION EFFECTS
CHEMISTRY
CHYMOTRYPSIN
DICHROISM
ELEMENTS
ENZYME INHIBITORS
ENZYMES
HALOGENS
HYDROLASES
IRRADIATION
LEGUMINOSAE
NONMETALS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PEPTIDE HYDROLASES
PHASEOLUS
PLANTS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
STRUCTURAL CHEMICAL ANALYSIS
THIOCYANATES
TRYPSIN