Thiaisoleucine and protein synthesis.
Thiaisoleucine is an isoleucine analogue having the gamma-methylene group of the valerianic carbon chain substituted by a sulphur atom. It has been demonstrated that thiaisoleucine is activated and transferred to tRNAIle by rat liver aminoacyl-tRNA synthetase and inhibits isoleucine incorporation into polypeptides in protein synthesizing systems from rat liver or rabbit reticulocytes, whereas it does not affect either leucine incorporation or ribosome run-off or polypeptide chain elongation rate. All tests were performed in comparison with O-methyl-threonine, an isoleucine analogue with the gamma-methylene group substituted by an oxygen atom. In all the reactions studied, both thiaisoleucine and O-methyl-threonine act as competitive inhibitors of isoleucine. With respect to O-methyl-threonine, thiaisoleucine shows higher activity as an isoleucine inhibitor.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000818:Animals; D011756:Diphosphates / Q000378:metabolism; D007532:Isoleucine / Q000031:analogs & derivatives* / Q000378:metabolism; D007700:Kinetics; D014176:Protein Biosynthesis; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis; D011817:Rabbits; D051381:Rats; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013912:Threonine / Q000031:analogs & derivatives / Q000378:metabolism
D011756:Diphosphates; D012346:RNA, Transfer, Amino Acyl; D007532:Isoleucine; D013912:Threonine; D000255:Adenosine Triphosphate; D000604:Amino Acyl-tRNA Synthetases