title: Purification and partial characterization of an intracellular aminopeptidase from Streptococcus salivarius subsp. thermophilus strain ACA-DC 114.
abstract: An intracellular aminopeptidase from Streptococcus salivarius subsp. thermophilus strain ACA-DC 114, isolated from traditional Greek yoghurt, was purified by chromatography on DEAE-cellulose and Sephadex G-100. The enzyme had a molecular weight of 89,000. It was active over a pH range 4.5-9.5 and had optimum activity on L-lysyl-4-nitroanilide at pH 6.5 and 35 degrees C with Km = 1.80 mmol/l; above 55 degrees C the enzyme activity declined rapidly. The aminopeptidase was capable of degrading substrates by hydrolysis of the N-terminal amino acid; it had very low endopeptidase and no carboxypeptidase activity. The enzyme was strongly inactivated by EDTA. Serine and sulphydryl group reagents had no effect on enzyme activity.
authors.affiliation: Laboratory of Dairy Research, Agricultural University of Athens, Greece.
authors.forename: E
authors.initials: E
authors.lastname: Tsakalidou
authors.forename: G
authors.initials: G
authors.lastname: Kalantzopoulos
mesh_terms: D000626:Aminopeptidases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D000818:Animals; D004492:Edetic Acid / Q000494:pharmacology; D004795:Enzyme Stability; D005516:Food Microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D013291:Streptococcus / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature; D015014:Yogurt / Q000382:microbiology*
chemical_list: D004492:Edetic Acid; D000626:Aminopeptidases