DNA催化活性的研究Ⅲ．多聚核苷酸的催化作用

STUDIES ON CATALYTIC ACTIVITY OF DNA MOLECULES Ⅲ.THE CATALYTIC FUNCTION OF POLYRIBOTIDE

以多聚腺苷酸（ｐｏｌｙＡ），多聚尿苷酸（ｐｏｌｙＵ）及其混合复性的ｐｏｌｙＡ·ｐｏｌｙＵ与乙酸－α－萘酯及坚牢蓝ＲＲ盐混合保温，研究了多聚核苷酸催化乙酸－α－萘酯水解的作用，结果表明：由ｐｏｌｙＡ·ｐｏｌｙＵ组成的双链ＲＮＡ具有与ＤＮＡ分子相似的催化活性，ｐｏｌｙＡ这一单链多聚物也能起催化作用，ｐｏｌｙＵ则没有这一功能。据此认为，核酸分子的催化活性与核糖２＇－位脱氧与否无关，而碱基的堆积为素酯分子的疏水奈环基团提供足够的疏水空间，则是催化活性所必须的。双链ＤＮＡ及双链ＲＮＡ都能满足这一条件，ｐｏｌｙＡ中嘌呤碱基堆积则刚能容纳下萘环，所以均能催化萘酯的水解；而ｐｏｌｙＵ中嘧啶碱基的堆积不足以容纳下萘环，因而不具备这一催化作用。

The color reaction of catalyzing α-Naphthylacetate to hydrolyze polyribotidepoly(A),poly(U)and their renaturated mixture poly(A)poly(U)incubated together withα-Naphylacetate and fast blue RR salt was studied.The result showed that the annealed poly(A)· poly(U) and the single strand polymers of Adenine were able to hydrolyze α-Naphthy-lacetate but poly(U)was not.It suggested that no matter that the2'-OH of riboes was deox-idated or not,its catalvtic ability was not affected,but the pattern of the bases stacking alongthe strand which provided enough hydrophobia region for naphthyl ring to insert were essen-tial to the catalvsis. DNA,dsRNA with the base-pair accommodated naphthyl ring easily andpoly(A)Adenine stack just accommodated one. Poly(U)with Uridine stack did not providesufficient region for a naphthyl ring,so only poly(U)was not able to catalyze α-Naphthylac-etate to hvdrolvze.