Dissecting the total transition state stabilization provided by amino acid side chains at orotidine 5'-monophosphate decarboxylase: a two-part substrate approach.
Kinetic analysis of decarboxylation catalyzed by S154A, Q215A, and S154A/Q215A mutant yeast orotidine 5'-monophosphate decarboxylases with orotidine 5'-monophosphate (OMP) and with a truncated nucleoside substrate (EO) activated by phosphite dianion shows (1) the side chain of Ser-154 stabilizes the transition state through interactions with the pyrimidine rings of OMP or EO, (2) the side chain of Gln-215 interacts with the phosphodianion group of OMP or with phosphite dianion, and (3) the interloop hydrogen bond between the side chains of Ser-154 and Gln-215 orients the amide side chain of Gln-215 to interact with the phosphodianion group of OMP or with phosphite dianion.
Barnett
Shonoi A
SA
Department of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, USA.
Amyes
Tina L
TL
Wood
Bryant M
BM
Gerlt
John A
JA
Richard
John P
JP
D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007700:Kinetics; D008954:Models, Biological; D015394:Molecular Structure; D009964:Orotidine-5'-Phosphate Decarboxylase / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity; D014542:Uridine Monophosphate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
D000596:Amino Acids; C409383:uridine 5'-hexadecylphosphate; C005417:orotidylic acid; D014542:Uridine Monophosphate; D009964:Orotidine-5'-Phosphate Decarboxylase