tRNA structure and binding sites for cations

✍ Scribed by Antoine Danchin

• Book ID: 102760213
• Publisher: Wiley (John Wiley & Sons)
• Year: 1972
• Tongue: English
• Weight: 917 KB
• Volume: 11
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1972.360110702

✦ Synopsis

Equilibrium dialysis and electronic and nuclear resonance spectroscopy show that tRNA cooperatively binds divalent metal ions a t very low concentrations (free metal concentration 3 x 10-6 M ) . The first two methods show that different purified tRNAs have a very similar behavior, including initiator tRNAyt. tRNAs with an extra arm in the clover-leaf model, however, appear to have a slightly different behavior.

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:

The binding can be described in terms of two classes of sites.

for the cooperativity Co++ > Mg++ > Mn++ for the weak binding sites Mn++ > Co++ > Mg++