1Rs/201s 11:ss PM Q 63.1hoo G 1/20/2015 o4:09 PM Grade boo Print Calculator Peri

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1Rs/201s 11:ss PM Q 63.1hoo G 1/20/2015 o4:09 PM Grade boo Print Calculator Periodic Table Question 14 of 19 sapling earning Hexokinase catalyzes the first step of glycolysis, in which glucose is phosphoryl ated to form glucose-6-phosphate Which of the following statements are accurate? Choose all that apply. n Because hexokinase brings the oH of glucose close to ATP, the hydroxyl group of water can enter the active site and hydrolyze ATF to ADP and Pi. n Most kinases require the presence of a monovalent metal ion cofactor to prevent ATP hydrolysis. Hexokinase consists of two domains, or lobes, that come together when glucose and the complex are bound. Hexokinase transfers the terminal phosphate of ATP to carbon 3 of glucose Hexokinase is a type of transferase that catalyzes the transfer of a phosphoryl group from ATP to a hexose. Hexokinase is found in the cytosol. OPrevious 8 Give up & View solution Annur a

Explanation / Answer

Options 1,3,5,6 are correct with respect to Hexokinase.

In the first reaction of glycolysis, the gama-phosphoryl group of an ATP molecule is transferred to the oxygen at the C-6 of glucose (magnesium ion is required as the reactive form of ATP is the chelated complex with magnesium (II) ion). This step is a direct nucleophilic attack of the hydroxyl group on the terminal phosphoryl group of the ATP molecule (Aleshin, 99). This produces glucose-6-phosphate and ADP. Hexokinase is the enzyme that catalyzes this phosphoryl-group-transfer. Hexokinase undergoes and induced-fit conformational change when it binds to glucose, which ultimately prevents the hydrolysis of ATP. It is also allosterically inhibited by physiological concentrations of its immediate product, glucose-6-phosphate. This is a mechanism by which the influx of substrate into the glycolytic pathway is controlled.

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