title: Properties and substrate specificity of the leucyl-, the threonyl- and the valyl-transfer-ribonucleic acid synthetases from Aesculus species.
abstract: 1. Leucyl- and threonyl-tRNA synthetases were partially purified up to 100-fold and 30-fold respectively from cotyledons of Aesculus hippocastanum and were largely separated from the other aminoacyl-tRNA synthetases. Valyl-tRNA synthetase was purified 25-fold from cotyledons of Aesculus californica. 2. Some properties are reported for the three enzymes when assayed by the [(32)P]pyrophosphate-ATP exchange technique. 3. beta-(Methylenecyclopropyl)alanine, isoleucine, azaleucine, norleucine and gamma-hydroxynorvaline acted as alternative substrates for the leucyl-tRNA synthetase; the enzyme's affinity for beta-(methylenecyclopropyl)-alanine and for isoleucine was about 80-fold less than that exhibited for leucine. 4. alpha-Cyclopropylglycine and alpha-cyclobutylglycine acted as alternative substrates for the valyl-tRNA synthetase.
mesh_terms: D000409:Alanine / Q000378:metabolism; D002848:Chromatography, DEAE-Cellulose; D005998:Glycine / Q000378:metabolism; D007532:Isoleucine / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D008025:Ligases / Q000032:analysis*; D010759:Phosphorus Isotopes; D010944:Plants / Q000201:enzymology*; D012343:RNA, Transfer / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology; D013912:Threonine / Q000378:metabolism; D014633:Valine / Q000378:metabolism
chemical_list: D010759:Phosphorus Isotopes; D007532:Isoleucine; D013912:Threonine; D012343:RNA, Transfer; D008025:Ligases; D007930:Leucine; D014633:Valine; D000409:Alanine; D005998:Glycine