Studies on the mung bean trypsin inhibitor--reduction and reoxidation of the disulfide bonds of the Lys active fragment.
Two peptide chains A1 and A2 of the Lys active fragment, linked via a couple of inter-disulfide bonds, could be separated from each other after reduction with dithiothreitol and gel filtration on Sephadex G-25. Reoxidation of the reduced peptide chain A1 resulted in recovering the inhibitory activity with 25% yield, based on the original activity of the Lys fragment. The A1 active fragment was further purified by affinity chromatography with immobilized trypsin. Sephadex G-25 gel filtration produced two forms of the A1 active fragment, the major fraction being a monomer and the minor one being a dimer with lower activity. The results obtained offered evidence of the evolution of mung bean inhibitor from an ancestral single-headed inhibitor by fused gene duplication with A2 as a connecting peptide. The CD spectra of the Lys fragment and the reoxidized peptide chain A1 were also compared.
D000596:Amino Acids / Q000032:analysis; D002942:Circular Dichroism; D004220:Disulfides / Q000032:analysis; D008239:Lysine; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010455:Peptides / Q000032:analysis; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013438:Sulfhydryl Compounds / Q000032:analysis; D014361:Trypsin Inhibitors / Q000032:analysis*
D000596:Amino Acids; D004220:Disulfides; D010455:Peptides; D013438:Sulfhydryl Compounds; D014361:Trypsin Inhibitors; D008239:Lysine