Sandbox Reserved 401: Difference between revisions
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During the first step of glycolysis, the gama-phosphoryl group af n ATP molecule is trasferred to the oxygen at the C-6 position of glucose. A magnesium ion is required as the reactive form of ATP is the chelated complex with magneium (II) ion. This is a direct nucleophillic attack of the hydroxyl group on the terminal phosphoryl group of ATP molecule. This reaction produces glucoe-6-phosphate, and ADP. | During the first step of glycolysis, the gama-phosphoryl group af n ATP molecule is trasferred to the oxygen at the C-6 position of glucose. A magnesium ion is required as the reactive form of ATP is the chelated complex with magneium (II) ion. This is a direct nucleophillic attack of the hydroxyl group on the terminal phosphoryl group of ATP molecule. This reaction produces glucoe-6-phosphate, and ADP. | ||
[[Image:Hexokinase mechanism.jpg]] | [[Image:Hexokinase mechanism.jpg]] | ||
== Structure == | |||
Hexokinases structure was first determined from yeast by Tom Steitz at the University of Yale. This compound is composed of a large homodimer of 920 amino acids in each chain. Each chain is about equal molecular weights. Hexokinase has a tertiary structure which includes an open alpha/beta sheet. There is a lot of variation associated with this structure. Its composed of three alpha helices, and five beta sheets. The open beta sheet is composed of four parallel sheets, and one antiparallel sheet. The beta loops,and alpha helices connect the beta sheets to produce this open alpha/beta sheet. Hexokinase is capable of binding two ligands, glucose, and glucose-6-phosphate. | |||