- 作者: Henry J. Tsai
- 作者服務機構: Pharmaceutical R&D laboratories, Development Center for Biotechnology, 101 Ln 169, Kang-Ning St, Hsi-Chih 221, Taipei County, 221, Taiwan, ROC
- 中文摘要: --
- 英文摘要: Human brain relies on a steady supply of glucose as the source of fuel, and type 1 hexokinase is the major isozyme governing the introduction of glucose to glycolysis in the brain. One unique regulatory property associated with type I isozyme is the alleviation of product inhibition by inorganic phosphate which binds to the N-terminal half, and the conformational change induced by inorganic phosphate must be propagated to the active site in the C-terminal half. With a single interdomain α-helix as the only covalent connection between the N- and C-terminal halves, the question arises as what role the interdomain α-helix plays at the interdomain signal transduction. Two mutants were constructed in an attempt to answer this question. The first mutant, A464P/E465G, with a helix breaker embedded in the interdomain α-helix had a smaller magnitude of phosphate alleviation than the wild type. The second mutant, with an insertion of seven additional residues between Gln 466 and His 467, had this phosphate relief property further diminished. Neither mutant showed dramatic changes nor the other kinetic properties. It is speculated that the interdomain α-helix is important for keeping the proper non-covalent contact so that transmission of the conformational changes across the N- and C-terminal half boundary can be achieved.
- 中文關鍵字: --
- 英文關鍵字: glucose 6-phosphate inhibition, inorganic phosphate relief, interdomain helix, mammalian hexokinase