Detection of the Recovery Substance for Cell Divison in UV-Irradiated Escherichia coli B -Stabilization of the Active Substance by Magnesium-

자외선 조사한 대장균 B 주의 세포분열 회복활성물질 -Magnesium에 의한 활성물질의 안정화-

Recovery component for cell division in UV-irradiated E. coli B was detected with use of the cell extract of E. coli B/r which is a resistant mutant of E. coli B against UV-irradiation. The active substance was non-dialyzable and increased the activity by adding B-NAD remarkably. One more factor for increasing or promoting the restoration recognized was magnesium. Magnesium was effective to stabilze the substance in procedure of isolation. Two active substances were obtained from sucrose gradient centrifugation. One of them was recovred from the botton area and the other from top area just below below surface. the former was not stabilized by magnesium, while the latter stabilized the activity by it remarkably. The former which did not require magnesium was insensitive to protease and the latter which required magnesium was sensitive to it. Both were insensitive to RNase and DNase. Recovery ratio was doubled by using nitrogen gas than aeration in purification process. DNA-ligase less mutant was revealed same activity on it's recovery ratio with the parent strain of E. coli K-12. The active substance stimulating the filament cell may exist as a complex which is inactivated easily in the dissociated state ana requrie B-NAD or magnesium.

자연선조사한 대장균B주의 세포분열회복활성분을 구명코저 자외선내성균인 대장균 B/r 주의 초음파추출액으로부터 활성성분分을 분리한 결과 $\beta$-NAD가 관여함이 발표되었다. 본고에서는$\beta$-NAD 이외 Magnesium이 활성물질의 안정화가 중요한 역할을 나타냄을 구명하였으며 10~30%의 서당밀 도구배원심분리에 의해 2 개의 새로운 활성부분이 있음을 확인하였다. 2 개의 활성물질 가운데 하나는 원심관의 최하부에 위치하였으며 또 다른 하나는 상부의 분자량 45,000 부위에서 회수되었다. 하부에 위치한 활성획분은 Mg++이 그 활성에 무관하였으나 상부의 저분자 활성부분은 $Mg^{++}$을 첨가하지 않으면 회수가 불가능하였다. 저분자활성부분은 pronase에 대해 감수성이었으며 DNA-ligase 는 아님이 추정되었다. 초원심분리과정에 $N_2$ gas를 처리할 경우 aeration에 비해 약 2 배의 활성이 나타났다. $Mg^{++}$은 $\beta$-NAD에 또하나의 회복활성 및 필수적인자로 요구된다고 생각된다.