title: Study of the rat liver S-adenosylmethionine synthetase active site with 8-azido ATP.
abstract: The active site of rat liver S-adenosylmethionine synthetase was studied using 8-azido ATP, a photolabile analogue of ATP. Both forms of the enzyme, tetramer and dimer, could be labelled by using concentrations of the analogue similar to the KmATP values for each form, 350 microM and 1 mM respectively. Labelling of both S-adenosylmethionine synthetase forms with 8-azido [alpha-32P]ATP, followed by tryptic digestion and purification by HPLC, afforded one specifically labelled peptide in each case. Identification of the labelled peptide by amino acid analysis and peptide sequencing, and comparison with the enzyme sequence, indicated that the same peptide (267-286) was modified in both enzyme forms. The results are discussed on the basis of the high degree of similarity that this peptide shows in all the known S-adenosylmethionine synthetase sequences.
authors.affiliation: Pharmazeutisch-Chemisches Institut, Universität Heidelberg, Germany.
authors.forename: H P
authors.initials: HP
authors.lastname: Deigner
authors.forename: J M
authors.initials: JM
authors.lastname: Mato
authors.forename: M A
authors.initials: MA
authors.lastname: Pajares
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000345:Affinity Labels; D000595:Amino Acid Sequence; D000818:Animals; D001386:Azides / Q000494:pharmacology*; D001665:Binding Sites; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D008716:Methionine Adenosyltransferase / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000345:Affinity Labels; D001386:Azides; D010455:Peptides; C017040:8-azidoadenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D008716:Methionine Adenosyltransferase