title: Purification and properties of guanine, queuine-tRNA transglycosylase from wheat germ.
abstract: Guanine, queuine-tRNA transglycosylase has been purified from wheat germ to homogeneity. The specific activity is 2,000 pmol h-1 mg-1 of protein. The enzyme has an apparent Mr = 140,000. It migrates as a single band with Mr = 68,000 on electrophoresis in sodium dodecyl sulfate gels, indicating two Mr = 68,000 subunits. Both guanine (Km = 6.0 X 10(-8) M) and queuine (KI = 9.5 X 10(-8) M) are substrates but 7-(aminomethyl)-7-deazaguanine is not. The enzyme requires a monovalent or a divalent cation; Na+ and Mg2+ are more effective activators than other cations. The optimum pH is 7.6. Six tRNA isoacceptors found in wheat germ are substrates for the enzyme.
mesh_terms: D000818:Animals; D002412:Cations; D007700:Kinetics; D008970:Molecular Weight; D010430:Pentosyltransferases; D010944:Plants / Q000201:enzymology*; D012343:RNA, Transfer / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D014166:Transferases / Q000302:isolation & purification* / Q000378:metabolism; D014908:Triticum / Q000201:enzymology
chemical_list: D002412:Cations; D012343:RNA, Transfer; D014166:Transferases; D010430:Pentosyltransferases; C020837:queuine tRNA-ribosyltransferase