• Applied Biological Chemistry
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• v.36 no.6
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• pp.539-546
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• 1993

This paper describes the purification and partial characteristics of aminopeptidase from Microccus sp. LL3 to utilize the microorganism as a potential agent for industrial application for the purpose of shortening ripening period of cheddar cheese. The optimal temperature and pH for enzyme activity were $35^{\circ}C$ and 7.0, respectively for L-leucine-p-nitroanilide as substrate. The enzyme remained stable for 10 minutes up to $50^{\circ}C$. The activity of aminopeptidase was stimulated by $Mg^{++}$ ion but strongly inhibited by $Hg^{++}$, metal complexing reagents, ethylenediaminetetraacetate (EDTA) and 1,10-phenanthroline. The enzyme was thought to be metallopeptidase. This enzyme had a broad substrate specificity, but was inactive on peptide with arginine as N-terminal amino acid. An intracellular aminopeptidase from Micrococcu sp. LL3 was purified by chromatography on DEAE-Sephacel and filtration on Sepacryl S-300. The enzyme has a molecular weight of 43,500.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.479-484
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• 1992

This study was undertaken to determine the effects of cultural conditions on cell growth and casein hydrolysis for cell production in order to add Micrococcus sp. LL3 as a potential agent for industrial application with aim of shortening ripening period and improving flavor. Optimum temperature for cell growth and caseinolysis was $30^{\circ}C$ and $37{\circ}C$, respectively, and optimum pH was 7.0. The enzyme remained stable up to $50^{\circ}C$. Hydrolysis patterns of casein were also observed on SDS-PAGE. Both ${\alpha}-casein$ and ${\beta}-casein$ were totally hydrolysed by enzymes from Micrococcus sp. LL3 during culture. A preferential attack on ${\beta}-casein$ was observed. Production of aminopeptidase which cleaved polypeptides was the highest in early stationary phase during cell growth.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.327-333
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• 1991

This study was carried out to determine the effects of media compositions on cell growth and casein hydrolysis for cell production in order to add Micrococcus sp. LL3 as a potential agent for industrial application for the shortening of ripening period. Monosaccharides like glucose, mannose and fructose were mare excellent as carbon source, but arabinose and xylose markedly inhibited cell growth and caseinolysis. Among the organic nutrients, yeast extract was more effective for cell growth and for caseolysis. However, inorganic nitrogen sources were less effective than organic sources. Urea inhibited cell growth severely. Cell growth and caseinolysis were rather increased a little in the broth containing 1% NaCl, and the organism tolerated and grew in relatively high concentrations of NaCl up to 9%. Addition of vitamin did not affect cell growth and caseolysis in level of $0.1\;{\mu}g/ml$ concentration. Cell growth and caseinolysis were stimulated by addition of glutamic acid and $MgSO_4$ with concentration of 0.2% and 0.05% respectively.