title: [Properties and substrate specificity of proteinase from buckwheat seeds].
abstract: A thiol proteinase was isolated from buckwheat seeds and purified 300-fold, using ammonium sulfate, acetone fractionation ion-exchange chromatography on Sephadex CM-50 and electrofocussing. The proteinase preparation obtained was found homogenous after polyacrylamide gel electrophoresis at pH 4.5. The molecular weight of the enzyme (75.000) was determined by gel-filtration through Sephadex G-100. The activation of proteinase by cysteine, 2-mercaptoethanol and dithiothreitol, its inhibition by p-chloromercurybenzoate and the absence of inhibition by diisopropyl fluorophosphate and EDTA suggest that the enzyme isolated is a thiol proteinase. The enzyme hydrolyzed many peptide bonds in the B-chain of insulin, showing high substrate specificity. The glutelin and globulin fractions of buckwheat seed proteins were hydrolyzed by the enzyme. It is assumed that the hydrolysis of reserve proteins of buckwheat seeds is the main function of the proteinase isolated.
mesh_terms: D002523:Edible Grain / Q000201:enzymology*; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D004789:Enzyme Activation; D008970:Molecular Weight; D010940:Plant Proteins / Q000378:metabolism; D012639:Seeds / Q000201:enzymology; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D013438:Sulfhydryl Compounds; D010450:Endopeptidases
vernacular_title: Svoistva i substratnaia spetsifichnost' proteinazy iz semian grechikhi