Mercury(II) binding to s4U in E.coli tRNAVal
AUTOR(ES)
Sunshine, Helen R.
RESUMO
The accessibility of the s4U base in native tRNAVal from E.coli was monitored by studying the binding of various mercurials. The relative binding order HgBr2[unk]HgCl2≫CH3HgOAc[unk]CH3HgCl[unk]PCMB parallels approximately the steric requirements of linear HgX2 or RHgX compounds for SN2 displacement by sulfur, although other factors are operative. Para-chloromercuri-benzoate (PCMB) does not bind the thiolated nucleotide unless the tertiary structure of the tRNA is opened up by removal of Mg2+ ions and heating to 40°. Under these conditions, equilibrium dialysis measurements using 14C-labeled PCMB showed one binding site (n = 0.93) with an association constant, K1, of 9 × 104M−1.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=343368Documentos Relacionados
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