| 摘要 |
PURPOSE: To provide a novel dipeptidase which is produced by Lactobacillus helveticus, has a specific molecular weight, isoelectric point, optimal temperature and optical pH, specifically hydrolyzes dipeptides whereby the substances causing bitter tastes can be removed from beverage, food products and medicines. CONSTITUTION: Lactobacillus helveticus such as Lactobacillus helveticus SBT 2171 (FERM-P-14381) is cultured in a medium, the culture mixture is centrifugpd to collect the cell bodies, which are suspended in a buffer solution, crushed with ultrasonic waves, the crushed product is centrifuged to collect the supernatant. The supernatant is purified with column chromatography to give this novel dipeptidase which has the amino acid sequence starting from the N- terminus given in the formula (X is an unidentified amino acid), about 50kDa (SDS electrophoresis) or about 49kDa (amino acid analysis) molecular weight, about 4.9 isoelectric point, about 55 deg.C optimal temperature and about 8.0 optimal pH, specifically hydrolyzes dipeptides, is inhibited its enzymatic activity by EDTA, 1,10-phenanthroline or bestatin, decreased with Cu<2+> or Fe<2+> and increased with Co<2+> . |
