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Synthesis and characterization of a spin‐labeled aminoacyl transfer ribonucleic acid
Author(s) -
Kabat David,
Hoffman Brian,
Rich Alexander
Publication year - 1970
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.1970.360090108
Subject(s) - chemistry , transfer rna , iodoacetamide , amino acid , cysteine , aqueous solution , aminoacyl trna , reagent , side chain , site directed spin labeling , rna , biochemistry , organic chemistry , polymer , enzyme , membrane , gene
Abstract Unfractionated yeast transfer ribonucleic acid (tRNA) was reacted in aqueous acetone solution with the sulfhydryl spin‐labeling reagnent, N ‐(l‐oxyl‐2,2,5,5‐tetramethyl‐3‐Pyrrolidinyl)iodoacetamide. Whereas tRNA stripped of amino acids reacted only slowly, there were sites on tRNA charged with cysteine which combined rapidly with the reagent. The latter class of spin‐label was quickly cleaved from the tRNA upon incubation in mildly alkaline solution (pH 8.0), suggesting that it was attached to the cysteinyl side chains. The paramagnetic resonance spectrum of column‐purified spin‐labeled cysteinyl tRNA showed that the spin‐label was partially immobilized as a result of its interaction with the tRNA. When the tRNA was slowly heated, an abrupt increase occurred in the rotational mobility of the paramagnetic amino‐acid side chain.