Which property distinguishes hepatic glucokinase from hexokinase?
- A High affinity for glucose with a low Km
- B Induction by insulin and a sigmoidal glucose saturation curve ✓
- C Inhibition by its product glucose-6-phosphate
- D Expression in nearly all tissues of the body
Correct answer: B. Induction by insulin and a sigmoidal glucose saturation curve
Explanation
Glucokinase (hexokinase IV) is expressed mainly in liver and pancreatic beta cells, has a high Km for glucose (about 10 mmol/L), shows cooperativity giving a sigmoidal curve, and is transcriptionally induced by insulin. It lacks product inhibition by glucose-6-phosphate, which kills options A, C and D: those describe hexokinase I-III, which have low Km, are inhibited by glucose-6-phosphate, and are ubiquitous.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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