title: Glycosylation, amino acid analysis and kinetic properties of a major Kunitz-type trypsin inhibitor from Acacia victoriae Bentham seeds.
abstract: An Acacia victoriae trypsin inhibitor (AvTI) was purified from the seeds of prickly wattle (A. victoriae Bentham) by salt precipitation, ion-exchange and gel filtration chromatography, and its degree of glycosylation, amino acid composition, and kinetic properties were determined. Gel electrophoresis revealed at least four glycoprotein bands in the crude extract, salt-precipitated and ion-exchange protein fractions, while the purified AvTI showed only one band and a degree of glycosylation of 2.06%. Glutamate (13.3%), aspartate (10.3%), leucine (7.62%) and lysine (7.01%) were the major amino acids in AvTI while the contents of sulphur-containing amino acids, cysteine (1.38%) and methionine (0.75%), as well as of tryptophan (1.17%) were low. Its dissociation constant (Ki) for the inhibition of bovine trypsin was found to be 1.06×10(-8)M, indicating a high affinity between AvTI and this enzyme, and its role as a competitive inhibitor was confirmed by a double reciprocal plot. These results complement our earlier studies which indicated the presence of three isoforms of this Kunitz-type trypsin inhibitor in prickly wattle seed.
authors.affiliation: E.H. Graham Centre for Innovative Agriculture and School of Agricultural and Wine Sciences, Charles Sturt University, Private Bag 588, Wagga Wagga, NSW 2678, Australia.
authors.forename: K Y
authors.initials: KY
authors.lastname: Ee
authors.affiliation: School of Chemical Sciences and Engineering, University of New South Wales, Sydney, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Industry and Investment NSW, Pine Gully Road, Wagga Wagga, NSW 2650, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Rehman
authors.affiliation: E.H. Graham Centre for Innovative Agriculture and School of Agricultural and Wine Sciences, Charles Sturt University, Private Bag 588, Wagga Wagga, NSW 2678, Australia. Electronic address: sagboola@csu.edu.au.
authors.forename: S
authors.initials: S
authors.lastname: Agboola
keywords: Glycoprotein; Kinetics; Trypsin inhibitor; Wattle seed