Thermal unfolding of yeast glycine transfer RNA

Abstract

The molecular unfolding of yeast tRNAGly was studied by a conbination of NMR spectroscopy, melting techniques and relaxation kinetics. From these studies the following pathway of unfolding was found. In a coupled melting transition the tertiary, the DHU [dihydrouridine] and the anticodon structure are disrupted. This is followed by the melting of the acceptor arm, while the T.psi.C arm, which only contains G.cntdot.C pairs, melts out last. Interestingly, during the first melting transition a new structure not belonging to the original cloverleaf structure is formed. The thermodynamic and kinetic parameters of the melting transitions were determined and are discussed in relation to earlier work. The present NMR experiments and earlier studies show that the ring current calculations based on the cloverleaf structure provide a good first-order interpretation of the NMR spectra of tRNA.