Millar D B
New Ideas Company, Rockville, Maryland 20852, USA.
Anal Biochem. 1998 Nov 15;264(2):271-8. doi: 10.1006/abio.1998.2840.
Sedimentation equilibrium studies of dilute solutions of tryptophan synthase reveal dissociation from the holoenzyme form, alpha 2 beta 2, into mixtures of alpha beta 2, small amounts of beta 2, and alpha as well as the original alpha 2 beta 2 holoenzyme. The holoenzyme form is stabilized by pyridoxal 5'-phosphate. A new sedimentation equilibrium analytical procedure shows the dissociation of the second alpha subunit to be negatively cooperative. The analytical procedure calculates theoretical error profiles with assumed values of the dissociation constant, k, and a cooperativity parameter until a match is made between one of the theoretical profiles and that computed from experimental data. The latter profile is calculated with an experimentally determined k and assumed values of the cooperativity parameter.
色氨酸合成酶稀溶液的沉降平衡研究表明，它会从全酶形式α2β2解离成αβ2、少量β2和α的混合物以及原始的α2β2全酶。全酶形式由磷酸吡哆醛5'-磷酸稳定。一种新的沉降平衡分析方法表明，第二个α亚基的解离具有负协同性。该分析方法通过解离常数k和协同性参数的假设值计算理论误差曲线，直到其中一个理论曲线与根据实验数据计算出的曲线相匹配。后者的曲线是用实验确定的k和协同性参数的假设值计算出来的。
