Structure-activity analysis of the purine binding site of human liver glycogen phosphorylase.
Human liver glycogen phosphorylase (HLGP) catalyzes the breakdown of glycogen to maintain serum glucose levels and is a therapeutic target for diabetes. HLGP is regulated by multiple interacting allosteric sites, each of which is a potential drug binding site. We used surface plasmon resonance (SPR) to screen for compounds that bind to the purine allosteric inhibitor site. We determined the affinities of a series of compounds and solved the crystal structures of three representative ligands with K(D) values from 17-550 microM. The crystal structures reveal that the affinities are partly determined by ligand-specific water-mediated hydrogen bonds and side chain movements. These effects could not be predicted; both crystallographic and SPR studies were required to understand the important features of binding and together provide a basis for the design of new allosteric inhibitors targeting this site.
Ekstrom
Jennifer L
JL
Exploratory Medicinal Sciences, Groton, CT 06340, USA.
Pauly
Thomas A
TA
Carty
Maynard D
MD
Soeller
Walter C
WC
Culp
Jeff
J
Danley
Dennis E
DE
Hoover
Dennis J
DJ
Treadway
Judith L
JL
Gibbs
E Michael
EM
Fletterick
Robert J
RJ
Day
Yasmina S N
YS
Myszka
David G
DG
Rath
Virginia L
VL
D000495:Allosteric Site; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003920:Diabetes Mellitus / Q000188:drug therapy; D004353:Drug Evaluation, Preclinical / Q000295:instrumentation / Q000379:methods; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D024981:Glycogen Phosphorylase / Q000037:antagonists & inhibitors*; D006801:Humans; D006860:Hydrogen Bonding; D008024:Ligands; D008099:Liver / Q000201:enzymology; D015394:Molecular Structure; D011687:Purines / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry
D004791:Enzyme Inhibitors; D008024:Ligands; D011687:Purines; D014867:Water; D024981:Glycogen Phosphorylase