Klebsiella pneumoniae가 생산하는 Glutamine synthetase의 정제 및 특성

Purification and Characterization of Glutamine synthetase of Klebsiella pneumoniae

K.pneumoniae의 nif 유전자 발현에 미치는 glnA 산물 (GS)의 영향을 살펴보기 앞서 K.pneumoniae의 GS를 분리.정제하여 그 성질을 조사하였다. K.pneumoniae의 GS는 분자량 약 600,000의 12개 동일 subunit으로 구성되어져 이었으며 최적 반응 pH 및 온도는 각기 pH 7.0, $37^{\circ}C$ 였고 pH 5-8사이에서 활성의 변화가 크지 않았으며 $57^{\circ}C$에서 10분간 열처리 할 때 50의 활성 감소가 나타났다. 또 암모니아 농도의 변화에 따라 adenylylation-deadenylylation 기작에 의한 활성조절기작이 E.coli GS와 동일 했으며 anti-E.coli GS 항체를 이용한 immunodiffusion에서도 K.pneumoniae GS가 E.coli GS와 혈청적으로 매우 유사함이 드러났다.

Glutamine synthetase (GS) of Kkbsiellu pmumonzae was purified and identified it's properties. It was determined to be composed of 12 identical subunits and it's molecular weight was about 600,000. It's optimum pH and temperature were identified as pH 7.0 and $37^{\circ}C$ respectively, and also there was no considerable variation of activity between pH 5 and 8. When GS was incubated at $57^{\circ}C$ for 10 min, it's activity was decreased to half of maximum activity. It was observed that K. pneumoniae has adenylylation-deadenylylation system which regulates activity of GS according to the quality and quantity of nitrogen source like GS of E. coli Also it's GS was very similar to that of E. coli. in structure deduced from the immunodiffuslon experiment using anti-E. coli GS antibody.