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트립토판 합성효소 잔기 치환체의 효소성질 결함에 대한 분석

Analysis of Mutant Tryptophan Synthases with Defective Enzymatic Properties

  • 김일 (부산대학교 자연과학대학 분자생물학과) ;
  • 신혜자 (동서대학교 응용공학부 환경공학전공) ;
  • 김한도 (부산대학교 자연과학대학 분자생물학과) ;
  • 임운기 (부산대학교 자연과학대학 분자생물학과)
  • Kim, Il (Department of Molecular Biology, College of Natural Sciences, Pusan National University) ;
  • Shin, Hye-Ja (Environmental Engineering Major, Division of Applied Engineering, Dongseo University) ;
  • Kim, Han-Do (Department of Molecular Biology, College of Natural Sciences, Pusan National University) ;
  • Im, Woon-Ki (Department of Molecular Biology, College of Natural Sciences, Pusan National University)
  • 발행 : 2004.04.01

초록

$\alpha$소단위체 56번 잔기가 치환된 돌연변이 (D56E/G/N) 트립토판 합성효소의 효소활성도는 매우 낮다. 이러한 돌연변이 효소에 $\alpha$$\beta$소단위체 특이 리간드를 처리하여 그 영향을 조사하였다. 양이온은 야생종과 잔기치환체에 다른 흡광도를 보여주었다. 반면, glycerophosphate는 모두 비슷한 양상의 흡광도를 보여주고 있다. glycerophosphate는 $\alpha$소단위체의 활성부위에 결합함으로 $\alpha$소단위체에 기질이 결합된 반응 단계에서는 56번 잔기가 $\alpha$$\beta$소단위체간의 이소조절에 관여하지 않고 있음을 시사한다. 따라서, 잔기 56번 치환 효소는 $\alpha$소단위체로부터 기질이 떨어진 이후에 일어나는 반응 단계에 결함이 있는 것으로 추정된다.

The mutant tryptophan synthases at $\alpha$Asp$^{56}$ have low catalytic activities. The enzymes were treated with $\alpha$ and $\beta$ subunit-specific ligands in the presence of L-serine and indoline. It was shown that the cations resulted in changes of absorbance patterns among the proteins, while glycerophosphate showed similar pattern of absorbance. The glycerophosphate binds to the active site of $\alpha$ subunit so that $\alpha$Asp$^{56}$ may not be involved in the allosteric control with the active site of $\alpha$ subunit occupied by substrate. The results suggest that $\alpha$Asp$^{56}$ may playa role in the step of a series of reaction occurring without bound substrates in the active site of asubunit.

키워드

참고문헌

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