Action of hexaamminecobalt on the activity of Serratia marcescens nuclease

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• 作者：Filimonova ; Maria ; Gubskaya ; Valentina ; Nuretdinov ; Il'dus ; Leshchinskaya ; Inna
• 关键词：DNA transition from B ; to A ; form characteristics ; hexaamminecobalt ; magnesium ; 4 ; (chloromercurio)benzoate ; nuclease ; Serratia marcescens
• 刊名：Biometals
• 出版时间：2003
• 出版年：2003
• 期刊代码：19_09660844
• 类别：bio
• 卷：16
• 期：3
• 页码：447-453
• 数据来源：sp

摘要

Using CD spectroscopic and kinetic analysis, a refined mechanism of Co(NH₃)₆³⁺ action on activity of Serratia marcescens nuclease was elucidated. The mechanism was identical with previously found mechanisms of Mg²⁺ and C₇H₅O₂Hg⁺. Similarly to Mg²⁺ and C₇H₅O₂Hg⁺, Co(NH₃)₆³⁺ binding to the DNA substrate induced changes in the secondary structure which resulted in changes of the enzymatic activity of the S. marcescens nuclease. Upon binding of 0.03 Co(NH₃)₆³⁺ per DNA phosphate, highly polymerized DNA displayed A-form characteristics. The DNA transition from B-form to A-form intermediate was followed by a decrease of the nuclease activity. The diminishing nuclease activity was consistent with diminishing values of Km and Kcat. Co(NH₃)₆³⁺ binding to the highly polymerized DNA caused a 1.7–2.8-fold decrease in Km, and 13.3–19.9 decrease in Vmax compared with Mg-DNA complex. A vast excess of Co(NH₃)₆³⁺ did not affect the activity of S. marcescens nuclease if the DNA in the assay mixture remained in its B-form conformation. Preincubation of S. marcescens nuclease with Co(NH₃)₆³⁺ did not influence the tertiary structure of the enzyme.