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tRNA structure and binding sites for cations
Author(s) -
Danchin Antoine
Publication year - 1972
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1972.360110702
Subject(s) - chemistry , divalent , cooperativity , cooperative binding , binding site , transfer rna , crystallography , ion , metal , metal ions in aqueous solution , stereochemistry , biochemistry , organic chemistry , rna , gene
Equilibrium dialysis and electronic and nuclear resonance spectroscopy show that tRNA cooperatively binds divalent metal ions at very low concentrations (free metal concentration 3 × 10 −6 M ). The first two methods show that different purified tRNAs have a very similar behavior, including initiator tRNA F met . tRNAs with an extra arm in the clover‐leaf model, however, appear to have a slightly different behavior. The binding can be described in terms of two classes of sites. The cooperative association of divalent ions binding first does not parallel a cooperative change in the hyperchromism of the tRNA, while the non‐cooperative association of the second class of divalent ions corresponds to the concentrations needed to obtain a cooperative melting of the tRNA. The temperature dependence of the number of binding sites and of their binding constants is also presented. The nature of the divalent ion gives the following efficiency: for the cooperativity Co ++ >Mg ++ >Mn ++ for the weak binding sites Mn ++ >Co ++ >Mg ++