A healthy 35-year-old man exhibits a peak serum glucose concentration of 215 mg/dL within 30 minutes of participating in a glucose tolerance test involving the consumption of 60 g of glucose. Two hours after ingestion, measurement of his serum glucose concentration shows it to be to 85 mg/dL. The observed decrease is due to the normal responses of tissues to insulin. In addition, part of the reduction is due to uptake and trapping of glucose within the liver cells, which is facilitated by which of the following enzymes?

Question

Quizplus · Accepted Answer

Glucokinase is the enzyme that facilitates the uptake and trapping of glucose within liver cells by phosphorylating glucose to glucose-6-phosphate, which is a crucial step in glucose metabolism. Hepatic glucokinase has a high K_m for glucose in order to ensure that the liver does not trap glucose before sufficient levels are obtained in the blood. This allows dietary carbohydrate to pass through the liver so that tissues such as the brain, skeletal muscle, erythrocytes, and kidney medulla can have access to the glucose. As the level of blood glucose increases, glucokinase will become more active, resulting in phosphorylation of more glucose thereby, trapping it in the hepatocyte.

A Healthy 35-Year-Old Man Exhibits a Peak Serum Glucose Concentration