Action of hexaamminecobalt on the activity of Serratia marcescens nuclease |
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| Authors: | Maria Filimonova Valentina Gubskaya Il'dus Nuretdinov Inna Leshchinskaya |
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| Institution: | (1) Department of Microbiology, Kazan State University, Kremliovskaya st. 18, Kazan, 420008, Russia;(2) Kazan Scientific Center of Russian Academy of Sciences, A.E. Arbuzov Institute of Organic and Physical Chemistry, Arbuzov st. 8, Kazan, 420088, Russia |
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| Abstract: | Using CD spectroscopic and kinetic analysis, a refined mechanism of Co(NH3)
6
3+
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)
6
3+
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)
6
3+
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)6
3+ 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)6
3+ 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)6
3+ did not influence the tertiary structure of the enzyme. |
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| Keywords: | DNA transition from B- to A-form characteristics hexaamminecobalt magnesium 4-(chloromercurio)benzoate nuclease Serratia marcescens |
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