Editing of errors in amino acid selection by an aminoacyl-tRNA synthetase prevents attachment of incorrect amino acids to tRNA, thereby greatly enhancing accuracy of translation of the genetic code. Editing of the non-protein amino acid homocysteine, a frequent type of an error-correcting process, involves reaction of the side chain sulfhydryl group of homocysteine with its activated carboxyl g...

Acetylcholine (ACh)- and high KCl-stimulated 45Ca uptake into rat uterine segments was inhibited by 3-deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL), and this inhibitory effect was attenuated by L-methionine (L-Met). Ca-depleted Ringer solution in which uterine muscle had been incubated with L-Met did not enhance the contractile response of another uterine segment to ACh and high K...

Evidence is presented that the editing mechanisms of aminoacyl-tRNA synthetase operate by two alternative pathways: pre-transfer, by hydrolysis of the non-cognate aminoacyl adenylate; post-transfer, by hydrolysis of the mischarged tRNA. The methionyl-tRNA synthetases from Escherichia coli and Bacillus stearothermophilus and isoleucyl-tRNA synthetase from E. coli, for example, are shown to rejec...

Homocysteine (hcy) is an intermediate metabolite in the metabolic pathway of cysteine and methionine. As a non-coded amino acid, hcy is not normally incorporated into protein. However, homocysteine can be recognized and activated by methionyl-tRNA synthetase (MetRs) to produce Hcy-thiolactone (HTL), which can react with the ε-amino group of a protein lysine residue. The N-hcy-linked protein car...