| 摘要 |
PURPOSE: To obtain a new endopeptidase acting on the inner peptide bonds of peptide chains to decompose the peptide but not decomposing the protein and giving the decomposition product useful for foods, beverages, medicines, etc., by culturing Lactobacillus helveticus. CONSTITUTION: A new endopeptidase which is produced from Lactobacillus helveticus, has an amino acid sequence started from the N-terminal of the formula, a mol.wt. of approximately 70kDa (a SDS electrophoresis method), an isoelectric point of approximately 4.8, the optimal temperature of approximately 30 deg.C, and the optimal pH of approximately 7.0, and acts on the inner peptide bonds of the peptide chains to decompose the peptide but not decompose the protein, and whose activity is inhibited with 1,10-phenathroline, ethylenediaminetetraacetic acid, p-chloromercurybenzenesulfonic acid, Cu<2+> , Zn<2+> and Fe<2+> . The enzyme is obtained by culturing Lactobacillus helveticus SBT 2171 (FERM P-14381) in a culture medium, collecting the cultured cells by a centrifugal method, crushing the collected cells and subsequently extracting the crushed cells. |
