| 摘要 |
PURPOSE:To obtain a new aminopeptidase capable of breaking the proline linkage at the amino terminal of a peptide, thus capable of decomposing peptides as a cause of the bitter taste of foods and beverages or medicines to eliminate bitter taste from such foods or medicines, through its production by Lactobaclllus helveticus. CONSTITUTION:Lactobacillus helveticus SBT 2171 strain (FERM P-14381) is inoculated into a medium and subjected to static culture at 37 deg.C for 10-16h followed by centrifuging the resultant culture fluid to collect the bacilli which are then suspended in a buffer solution and subjected to ultrasonic crushing treatment, and the crushed product is centrifuged; the resultant supernatant is then subjected to e.g. column chromatography to separate and purify the product, thus obtaining the objective new aminopeptidase which has the following characteristics: molecular weight: about 95kDa (SDS electrophoresis), about 93kDa (amino acid analysis); isoelectric point: about 4.9; optimum temperature: about 50 deg.C; optimum pH: 6-8; activity: specifically decomposes a protein with proline at the amino terminal; and inhibition of acitivity: inhibited by ethylenediaminetetraacetic acid, bestatin, etc., Zn<2+>, Fe<2+>, Cu<2+>, and promoted by Co<2+>. |
