Portal de Periódicos da CAPES

Effects of Polyamines on In Vitro DNA Synthesis by DNA Polymerases from Calf Thymus

1976; Oxford University Press; Volume: 79; Issue: 5 Linguagem: Inglês

10.1093/oxfordjournals.jbchem.a131157

1756-2651

Shonen Yoshida, Shigeo Masaki, Teruo Ando,

Biopolymer Synthesis and Applications

DNA synthesizing reactions catalyzed by both large and small species of calf thymus DNA polymerase (DNA polymerase-α and -β) [EC 2.7.7.7] were stimulated to comparable extents by the presence of spermidine or spermine, and it was not possible to differentiate these two species in terms of their sensitivities to polyamines. Optimal concentrations for stimulation were 0.5–1.0 mM for spermidine and 2-10 μ M for spermine. Excess polyamines strongly inhibited the reactions. The modes of stimulation were as follows: 1) Stimulation was observed with templates bearing long single-stranded sections when either natural DNA or synthetic homopolymer-oligomer duplex was used. 2) The natural DNA-dependent reaction was stimulated by polyamines at suboptimal concentrations of Mg2+; the apparent Km value for Mg2+ was lowered on adding polyamines, while the Vmax value was unchanged. When synthetic homopolymer-oligomer duplex was used as a template, the reaction was stimulated by spermidine even at the optimal concentration of Mn2+. 3) Polyamines markedly influenced the salt requirements of the reactions of DNA polymerase. Spermidine could replace salts such as KCl or NaCl at concentrations less than 1/100 of those of salts.