한국식품영양학회지 (The Korean Journal of Food And Nutrition)
- 제9권4호
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- Pages.372-378
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- 1996
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- 1225-4339(pISSN)
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- 2287-4992(eISSN)
이소루신 생합성 과정에서 Serratia marcescens Threonine Dehydratase의 조절 역할
The Regulatory Role of Serratia marcescens Threonine Dehydratase in a Isoleucine Biosynthesis
초록
최소 배지에 여러 아미노산을 첨가하여 배양시킨 Serratia marcescens ATCC 25419 세포 추출물에서 threonine dehydratase의 비활성을 조사한 결과 이소루신은 1~4mM에서 효소의 비활성을 100~140% 정도 증가시킨 반면 15~30mM에서 25~80% 정도 감소시켰다. 루신은 효소의 비활성을 1~120mM에서 60% 이상 감소시켰다. 한편, 발린은 효소의 비활성을 1~4mM에서 20% 정도, 8~10mM에서 10% 정도 감소시켰으나 20mM에서 효소의 비활성을 원래대로 회복시켰다. 각 2mM 농도의 이소루신과 발린 그리고 이소루신과 루신은 효소의 비활성을 각각 75, 50%씩 증가시킨 반면 세 아미노산을 각각 2과 10mM씩 동시 첨가했을 경우에는 각각 25, 58%씩 감소시켰다. 글리옥실산은 효소의 비활성을 75%, 이마다졸, 피루브산,
The effects of branched chain amino acids and metabolites in growth media on the biosynthesis of Serratia marcescens threonine dehydratase activity were examined. The enzyme activity was decreased above 60% by leucine among the range from 1 to 20 mM, and the enzyme activity was decreased approximately 20% by a low concentration of valine (1 to 4 mM), but not affected at high concentration (20 mM). However, the enzyme activity was increased approximately 100 to 140% by a low concentration of isoleucine (1 to 4 mM), but decreased approximately 25 to 80% at high concentration (15 to 30 mM). The enzyme activity was decreased by 25 and 58% by the simultaneous addition of all three branched chain amino acids at 2 and 10 mM concentration, respectively, but increased by 75 and 50% by the combination addition of isoleucine plus valine and isoleucine plus leucine at 2 mM, respectively. cAMP was decreased the enzyme activity approximately 10 to 40% by a low concentration (1 to 2 mM), but increased by 80% at high concentration (10 mM). These data suggest that S. marcescens threonine dehydratase should be multivalently repressed by branched chain amino acids, but positively regulated by a low isoleucine concentration and may play a regulatory role in an isoleucine biosynthetic pathway unlike the E. coli K-12 enzyme.