RESUMO
The properties and functions of the DNA topoisomerases are reviewed on the basis of the literature and the author's own data. The techniques of isolation and characterization of the covalent complexes of the topoisomerases with DNA are described.
Assuntos
DNA Topoisomerases Tipo I/metabolismo , DNA/metabolismo , Animais , Sequência de Bases , Ciclo Celular , Células Cultivadas , Cricetinae , Cricetulus , DNA Topoisomerases Tipo I/isolamento & purificação , DNA Super-Helicoidal/metabolismo , Eletroforese em Gel de Ágar , Feminino , Peixes , Cinética , Novobiocina/farmacologia , Conformação de Ácido Nucleico , Oócitos/enzimologiaRESUMO
A new DNAase was isolated from unfertilized loach eggs. The enzyme is activated by bivalent metal ions (Mg2+, Ca2+, Mn2+) and is inhibited by Na+ and N-ethylmaleimide. The maximal activity of DNAase lies within the pH range of 9.0-9.5. The enzyme is thermostable and predominantly hydrolyzes the two-chain DNA by producing one-chain ruptures. The DNAase activity during the purification procedure and enzymatic analysis was determined by a highly sensitive method based on registration of superhelical plasmid or phage DNA conversion into open circular or linear molecules.
