title: Insight into the biochemical characteristics of a novel glucokinase gene mutation.
abstract: Glucokinase (GCK) acts as a glucose sensor and regulates β-cell insulin secretion. The heterozygous mutations in the gene encoding GCK cause a reduction of the enzyme activity, which results in a monogenic form of diabetes, maturity-onset diabetes of the young. In the present study, we identified and functionally characterized a novel missense mutation in the GCK gene, which results in a protein mutation Glu(339)→Lys (E339K), from a Chinese family with hyperglycemia. The same GCK mutation that co-segregated with diabetes phenotype was identified in five members of this family but was not found in 200 healthy control individuals. We expressed and affinity-purified the GCK proteins from bacterial expression system that carries mutation (E339K) and fused to glutathione S-transferase. The expressed GCK protein was subjected to the measurement of its biochemical effects of the missense mutation on GCK activity. Our results showed that the mutation reduced the GCK protein yield. The enzymatic kinetics and the thermal stability analysis on the recombinant GCK proteins revealed that the mutation inactivates enzyme kinetics and severely impaired the GCK protein stability.
authors.affiliation: Department of Endocrinology, The Third Affiliated Hospital of Sun Yat-sen University, Research Center for Diabetes Care of Guangdong Province, 600 Tianhe Road, Guangzhou, 510630, Guangdong, People's Republic of China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Shen
authors.forename: Mengyin
authors.initials: M
authors.lastname: Cai
authors.forename: Hua
authors.initials: H
authors.lastname: Liang
authors.forename: Hongwei
authors.initials: H
authors.lastname: Wang
authors.forename: Jianping
authors.initials: J
authors.lastname: Weng
mesh_terms: D044466:Asian People / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000235:genetics; D005260:Female; D005941:Glucokinase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000201:enzymology* / Q000235:genetics; D008297:Male; D020125:Mutation, Missense; D010375:Pedigree; D055550:Protein Stability
chemical_list: D005941:Glucokinase