title: Active form of Pseudomonas mevalonii 3-hydroxy-3-methylglutaryl coenzyme A reductase.
abstract: Based on multiple gel permeation chromatographic experiments, we report a Stokes radius of 59.7 A for Pseudomonas mevalonii 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase; EC 1.1.1.88) and its His381Asn, His381Gln, and His381Lys mutant enzymes. Comparison of this Stokes radius with the radius calculated from the crystal structure indicated that the active form of P. mevalonii HMG-CoA reductase was a hexamer and not a dimer as previously thought. The Stokes radius, an S26,w of 11.0, and an estimated V of 0.723 were used in the Svedberg equation to calculate an anhydrous molecular mass of 270,084 Da for P. mevalonii HMG-CoA reductase (monomer mass 45,538 Da), consistent with the enzyme being a hexamer in solution. The Stokes radii of all standard proteins examined correlated with the inverse error function complement of their partition coefficient, Kd. Kd did not correlate with logarithm of the standard protein's molecular weight. Eight nonstandard proteins had Stokes radii that matched their crystallographic radii of longest axis. This indicated that the frozen conformation of a protein in its crystal form can dictate restraints on its shape in solution.
authors.affiliation: Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907-1153, USA. rogers@purdue.edu
authors.forename: K S
authors.initials: KS
authors.lastname: Rogers
authors.forename: V W
authors.initials: VW
authors.lastname: Rodwell
authors.forename: P
authors.initials: P
authors.lastname: Geiger
mesh_terms: D002850:Chromatography, Gel; D003911:Dextrans; D004789:Enzyme Activation; D005782:Gels; D006903:Hydroxymethylglutaryl CoA Reductases / Q000737:chemistry*; D007202:Indicators and Reagents; D008970:Molecular Weight; D011485:Protein Binding; D011487:Protein Conformation; D011549:Pseudomonas / Q000201:enzymology*; D014461:Ultracentrifugation
chemical_list: D003911:Dextrans; D005782:Gels; D007202:Indicators and Reagents; C025614:sephadex; D006903:Hydroxymethylglutaryl CoA Reductases