Answer:
A. The conformational shift that occurs when glucose, but not water, enters the active site prevents water from hydrolyzing ATP. True
B. Hexokinase consists of two domains, or lobes, that come together when glucose and the MgATP2–MgATP2– complex are bound. True
C. Hexokinase is a type of transferase that catalyzes the transfer of a phosphoryl group from ATP to a hexose. True
Explanation:
A. Hexokinase suffers and conformational changes by binding glucose in a reaction that prevents ATP hydrolysis.
B. Hexokinase is an enzyme with two domains that function by binding to the substrate (i.e., glucose). The region linking both protein domains is responsible for the catalytic activity.
C. Hexokinase is a type of transferase that catalyzes the transfer of a phosphoryl group from ATP to a hexose. During the first stage of glycolysis, the hexokinase transfers one phosphorous group from magnesium-ATP (Mg-ATP) to one hexose molecule, such as fructose, mannose or glucose.
False statements:
- Most kinases require the presence of a monovalent metal ion cofactor to prevent ATP hydrolysis. False: In canonical kinases, conserved amino acids bind to divalent metal ions before the transference of the phosphate group to their substrates.
- Hexokinase is found in the mitochondrial membrane. False: Hexokinase is found in the cytosol.
- Hexokinase transfers the terminal phosphate of ATP to carbon 3 of glucose. False: Hexokinase catalyzes the transfer of the terminal phosphate ATP to form glucose 6-phosphate.
