[Structure of the active center of the catalytic subunit of histone kinase]

A number of unknown ATP analogues is isolated when studying the structure of the active site of catalytic histonekinase subunit. Adenosine-5'-chloromethanepyrophosphonate adenosine-5'-(beta-bromoethanepyrophosphonate) and adenosine-5'-(p-fluorosulphonylphenylphosphate) were isolated under the reaction of chloromethanephosphonic acid, beta-bromoethanephosphonic acid and n-phenolsulphofluoride respectively with AMP imidazolide. Adenosine-5'-(beta-chloroethylphosphate) was obtained from AMP morpholide and ethylenechorohydrine. Adenosine-5'-chloracetylaminomethanephosphonate and adenosine-5'-(p-fluorosulphonylbenzoylaminomethanephosphonate) were obtained in the reaction of chloroacetyc anhydride and n-fluorosulphonylbenzoylchloride. Adenosine-5'-(p-aminophenylphosphate) is synthesized under the reduction of AMP mononitrophenyl ester. The treatment of the former with chloroacetyc anhydride produced adenosine-5'-(p-chloroacetylaminophenylphosphate. Interaction of ATP analogues obtained and also of early synthesized adenosine-5'-chloromethanephosphonate and adenosine-5'-(beta-bromoethanephosphonate) with homogenous catalytic histonekinase subunit is studied. The decrease in the reaction rate of Hi histone phosphorylation is found to take place. pH optimum of the enzyme inactivation with adenosine-5'-chloromethanepyrophosphonate and adenosine-5'-(beta-chloroethylphosphate) and the protective effect of the substrate (ATP) indicate covalent blocking imidazole ring in the active site. The date obtained suggest that the functional group of the active site of catalytic histonekinase subunit is histidine imidazole ring located close to terminal ATP phosphate.