摘要
本文应用荧光光谱法和CD光谱法测定了天冬氨酸酶在不同浓度盐酸胍中变性时的构象与活力变化,并测定了天冬氨酸酶在不同浓度盐酸胍中变性时的巯基暴露速度。发现一部分色氨酸残基位于分子疏水核内部,另一部分位于分子表面;至少一部分酪氨酸残基与其相邻近基团形成氢键。该酶的大部分巯基位于分子内部结构比较稳定的区域而不在分子表面。低浓度盐酸胍作用下,构象发生明显变化,而活力维持原水平;盐酸胍达到一定浓度后,活力才发生骤然下降。CD谱表明,α-螺旋构象维持整个分子构象,因而对于维持活性中心构象是重要的。
Fluorescence and circular dichroism spectra of aspartase were obtained in guanidine hydrochloride of different concentrations. Reactive thiol groups during denaturation of aspartase in guanidine hydrochlorid of different concentrations were monitored. It was found that some tryptophan residues were on the surface of the enzyme and others in the hydrophobic interior. Some tyrosine residues form the H-bonds with near groups. Most sulfhydryl groups are in the interior of the enzyme rather than on the surface. The activity of the aspartase depends on the high content of α-Helix. α-Helix is important to sustain the entire conformation of the enzyme and the avtive site's conformation.
出处
《生物化学杂志》
CAS
CSCD
1990年第5期432-436,共5页
关键词
天冬氨酸酶
变性
构象
Aspartase, Denaturation, Conformation
