Serratia marcescens ATCC 25419가 생산하는 Acetolactate Synthase Isozyme의 특성

The Properties of Acetolactate Synthase Isozyme Produced by Serratia marcescens ATCC 254 19

Serratia marcescens ATCC 25419를 질소원이 풍부한 BHI 배지에서 황산 암모늄 분별 침전을 시킨 후 DAEA-Sephacel chromatography, Phenyl-Sepharose hydrophobic chromatography, Sephacryl S-400 gel filtration, native gel elution을 거쳐 ALS isozyme Rf 0.83을 분리하였다. 분리한 ALS isozyme Rf 0.83의 native 형태는 gel filtration을 이용하여 분자량을 측정한 결과, 531,400이었고, SDS-PAGE를 수행한 결과 55,000의 large subunit와 38,900의 small subunit로 구성된 multimer임을 알 수 있었다.

One acetolactate synthase isozyme which has Rf value of 0.83 on polyacrylamide gel electrophoresis was purified from Sewatia marcescens ATCC 25419 by ammonium sulfate fractionation, DEAE-Sephacel chromatography, Phenyl-Sepharose chromatography, Sephacryt S-400 gel filtration followed by native gel elution. The native molecular weight of the enzyme was determined to be 531,400 by gel filtration method, and SDS-polyacrylamide gel electrophoresis separated the native enzyme into two polypeptides having molecular sizes of 55,000 and 38,900 respectively. In kinetic parameters, $K_m$ value for pyruvate was 2.54 mM, and $V_{max}$ was 21.75 nmoie/min/mg. The enzyme showed maximal activity around pH 8.0 and optimal temperature of the acetolactate formation was $37^{\circ}C$. Feedback inhibition studies indicate that the purified enzyme is rather resistant to branched chain amino acids when compared with acetolactate synthase isozymes of plants or other enterobacteria.