アミノアシルtRNA合成反応における二価陽イオンとポリアミンの役割

抄録

Requirement of Mg²⁺ in aminoacyl-tRNA formation has been well established. Replacement of Mg²⁺ requirement by various cations, such as Mn²⁺, Ca²⁺, Co²⁺, K⁺ and NH⁺₄ has also been reported. Polyamines, such as spermine, spermidine and putrescine, could also replace Mg²⁺ requirement in several aminoacyl-tRNA formations.
The role of these cations in the reaction was studied and it was found that these cations played two distinct roles; that is, (1) to bind to tRNA to activate it to be charged with amino acids, (2) to bind tightly to aminoacyl-tRNA synthetase, probably at its active center, which is necessary for the enzyme to be active. Mg²⁺ could play both the role (1) and (2), whereas polyamines could play the role (1). Mn²⁺ seemed to be very important to play the role (2).
Concerted mechanism of aminoacyl-tRNA formation in the presence of polyamines is also discussed.