Abstract
The effects of purine catabolites in growth media on the biosynthesis of Serratia marcescens and Lactobacillus plantarum purine nucleoside phosphorylase (PNP) activity were examined. Serratia PNP activity was decreased approximately by 30% in the presence of high concentrations of inosine $(5{\sim}15\;mM)$, but was not affected at low concentrations of inosine $(0.1{\sim}1\;mM)$. However, Lactobacillus PNP activity was increased above 60% by inosine among the range from 5 to 15 mM. Serratia PNP activity was decreased approximately by 45% in the presence of high concentrations of hypoxanthine $(5{\sim}15\;mM)$, but was not affected at low concentrations of hypoxanthine $(0.1{\sim}0.5\;mM)$. Lactobacillus PNP activity was increased approximately by 20% in the presence of low concentrations of hypoxanthine $(0.1{\sim}0.5\;mM)$, and increased approximately by $50{\sim}65%$ in the presence of concentrations of hypoxanthine $(1{\sim}15\;mM)$. Serratia and Lactobacillus PNP activity was increased 20% by low concentrations of uric acid (0.5 mM), but was decreased $40{\sim}80%$ at high concentrations of same purine catabolite $(10{\sim}15\;mM)$. These data suggest that purine nucleoside phosphorylase in Serratia marcescens ATCC 25419 and Lactobacillus plantarum ATCC 8014 is positively regulated by a low uric acid concentration, and then may play a regulatory role in a purine nucleotide catabolic pathway.
최소 배지와 MRS 배지에 여러 퓨린 뉴클레오시드을 첨가하여 각각 호기적과 혐기적 조건하에서 배양시킨 Serratia marcescens ATCC 25419와 Lactobacillus plantarum ATCC 8014 세포 추출물에서 PNP의 비활성도를 조사한 결과 이노신은 5 mM 이상의 농도에서 Serratia PNP의 비활성도를 대조군과 비교하여 30% 정도 감소시켰으나, Lactobacillus PNP의 비활성도를 60% 이상 증가시켰다. 히포잔틴은 $0.1{\sim}0.5\;mM$의 낮은 농도에서는 Serratia PNP의 비활성도에 거의 영향을 주지 않았으나, 5 mM 이상의 농도에서는 45% 정도를 감소시켰다. 하지만 히포잔틴은 $0.1{\sim}1\;mM$의 낮은 농도에서는 Lactobacillus PNP의 비활성도를 20%, $1{\sim}15\;mM$의 농도에서는 $50{\sim}65%$ 정도 증가시켰다. 한편, 요산은 0.5 mM의 농도에서 Serratia와 Lactobacillus PNP의 비활성도를 20% 정도 증가시킨 반면, $5{\sim}10\;mM$의 농도에서 $20{\sim}25%$ 정도, 그리고 15 mM의 농도에서는 $60{\sim}80%$ 감소시켰다. 이러한 결과들로부터 5 mM 이상 농도의 이노신과 히포잔틴은 Serratia PNP의 비활성도를 30%이상 감소시킨 반면, Lactobacillus PNP의 비활성도를 60% 이상 증가시켰으며 낮은 농도(0.5 mM)의 요산은 효소의 비활성도를 증가시키고 높은 농도(15 mM)의 요산은 감소시키는 등 퓨린 뉴클레오티드 분해 대사 과정에서 요산은 Serratia marcescens와 Lactobacillus plantarum PNP 생합성의 조절 역할을 하는 것으로 사료된다.