蛇肌果糖1，6－二磷酸酯酶的R态和T态的构象

几种高活性形式的蛇肌果糖１，６－二磷酸酯酸的紫外差光谱与酶在尿素或盐酸胍中差光谱相似，它们的酶学性质及巯基暴露的程度各不相同，提示这些高活性形式的酶的构象呈稳定的松驰状态（Ｂ态），构象松驰的程度也各不相同。受果糖２，６－二磷酸、ＡＭＰ和过量底物抑制的酶处于三种不同的低活性状态，它们的构象特征与Ｒ态相反，提示此三种低活性酶构象处于较紧凑状态（Ｔ态）。这几种Ｔ态酶流基暴露的程度，受蛋白水解酶限制性酶解的速度不同，说明这些Ｔ态酶的构象的紧凑程度是有差异的。蛇肌酶的不同的活化状态所具有不同的稳定的构象状态，在能量上可能相差很小，便于受到多种因子的调节。这可能是别构酶所普遍具有的现象。

The Comformations of R and T States of Snake Muscle Fructose 1, 6-Bisphosphatase

There are several forms of snake muscle Fructose 1,6-bisphosphathe with higher activity at pH 7.5.The U.V.difference spectra resemble those of the enzyme in low concentration of urea or guanidine hydrochloride. Those forms of FruP2ase which are at a relaxed conformation are designated as R slotes. Results indicate that the R states are different from each other in the conformation and property such as Km, Mg2 effects and AMP inhibition etc. When the enzyme is inhibited by AMP,Fru2,6P2 or excess substrate,the inhibited forms of the enzyme which are at a compact con formation are designated as T states.T states of the enzyme are different from each other in the exposed snlfuydryl groups of the enzyme and the velocity of Proteolysis by subtilisin or trypsin. On the basis of the observations we propose that nuder various conditions snake muscle FruP2ase could be present in different activated and inhibited states.These conformational slotes are relatively stable.The differences of the free energy between these conformational states are small,so that the allosteric enzyme could be easily regulated allosterically from one state to another state using the ligand binding energy.