title: Enzyme kinetics and molecular modeling studies of G6PD(Mahidol) associated with acute hemolytic anemia.
abstract: G6PD(Mahidol) enzyme is the most common variant in the Achang Chinese ethnic group and clinically manifests as class II. In this study, G6PD(Mahidol) enzyme was characterized by molecular modeling to understand its kinetics. G6PD(Mahidol), G6PD(G487A) and G6PD(WT) proteins were heterologously expressed in the G6PD-deficient DF213 E. coli strain, purified and their steady-state kinetic parameters were determined. Compared with G6PD(WT), the Km, and Vmax of NADP+ with G6PD(G487A) were about 28-fold and 12-fold lower, respectively. The Ki values of dehydroepiandrosterone (DHEA), NADPH and ATP with G6PD(G487A) showed 29.5-fold, 2.36-fold reduction and 1.83-fold increase, respectively. A molecular modeling of G6PD(G487A) was performed based on the X-ray structure of human G6PD (PDB: 2BH9). It is suggested that Ser-163 might affect the stability of G6PD(G487A) alpha-helix d and beta-strand E, besides the conformation of beta-strand D. In conclusion, the biochemical and structural properties of G6PD(G487A) and G6PD(WT) enzymes are significantly different, which may be responsible for clinical diversity of G6PD deficiencies.
authors.affiliation: Department of Biochemistry, Kunming Medical University, Kunming 650031, China.
authors.forename: Hui-Ru
authors.initials: HR
authors.lastname: Lu
authors.forename: Qiong-Ling
authors.initials: QL
authors.lastname: Tang
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Hong-Jun
authors.initials: HJ
authors.lastname: Li
authors.forename: Dan-Yi
authors.initials: DY
authors.lastname: Li
authors.forename: Yin-Feng
authors.initials: YF
authors.lastname: Yang
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Tong
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Zhang
authors.forename: Yue-Chun
authors.initials: YC
authors.lastname: Zhu
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000743:Anemia, Hemolytic / Q000201:enzymology* / Q000209:etiology; D044466:Asian People; D003198:Computer Simulation; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics*; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000150:complications / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D009154:Mutation
chemical_list: D005954:Glucosephosphate Dehydrogenase