Difference Between Hexokinase and Glucokinase

The main difference between hexokinase and glucokinase is that the hexokinase is an enzyme present in all cells whereas the glucokinase is an enzyme only present in the liver. Furthermore, hexokinase has a high affinity towards glucose while glucokinase has a low affinity towards glucose.

1. Why does the liver use glucokinase?
2. What is the function of hexokinase?
3. Why does glucokinase have a low affinity for glucose?
4. Why is hexokinase low km?
5. Is hexokinase in the liver?
6. Is glucokinase induced by insulin?
7. What happens if hexokinase is inhibited?
8. What is hexokinase deficiency?
9. What is hexokinase method?
10. Is glucokinase a hexokinase?
11. What is glucokinase inhibited by?
12. Does hexokinase or glucokinase have a higher affinity for glucose?

Why does the liver use glucokinase?

Glucokinase functions as the glucose sensor in the beta cell by controlling the rate of entry of glucose into the glycolytic pathway (glucose phosphorylation) and its subsequent metabolism. In the liver, glucokinase plays a key role in the ability to store glucose as glycogen, particularly in the postprandial state.

What is the function of hexokinase?

Hexokinase is the initial enzyme of glycolysis, catalyzing the phosphorylation of glucose by ATP to glucose-6-P. It is one of the rate-limiting enzymes of glycolysis. Its activity declines rapidly as normal red cells age.

Why does glucokinase have a low affinity for glucose?

Glucokinase phosphorylates glucose only when it is abundant because it has about a 50-fold affinity for glucose than does hexokinase. The role of glucokinase is to provide glucose 6-phosphate for the synthesis of glycogen, a storage form of glucose (Section 21.4), and for the formation of fatty acids (Section 22.1).

Why is hexokinase low km?

Hexokinase is also inhibited by glucose-6-phosphate. ... So, because of that hexokinase actually has a higher affinity for glucose (low Km), which means that it really wants to bind to glucose and do its job. Glucokinase, then, has a low affinity (high Km), so it won't bind quite so easily or quickly.

Is hexokinase in the liver?

Glucokinase (hexokinase D) is a monomeric cytoplasmic enzyme found in the liver and pancreas that serves to regulate glucose levels in these organs.

Is glucokinase induced by insulin?

Insulin is by far the most important of the hormones that have direct or indirect effects on glucokinase expression and activity in the liver. Insulin appears to affect both glucokinase transcription and activity through multiple direct and indirect pathways.

What happens if hexokinase is inhibited?

Whenever the concentration of glucose6-phosphate in the cell rises above its normal level, hexokinase is temporarily and reversibly inhibited, bringing the rate of glucose-6phosphate formation into balance with the rate of its utilization and reestablishing the steady state.

What is hexokinase deficiency?

Hexokinase deficiency manifests itself primarily as nonspherocytic hemolytic anemia (NSHA). The signs and symptoms of hexokinase deficiency are very similar to those of pyruvate kinase deficiency, a more common inherited cause of hemolytic anemia , and may include jaundice , fatigue, lethargy, and pale skin..

What is hexokinase method?

The hexokinase/glucose-6-phosphate dehydrogenase (G6PD) method developed by the American Association for Clinical Chemistry has been accepted as the reference method for glucose determination. ... Glucose is phosphorylated by hexokinase in the presence of ATP to form glucose-6-phosphate.

Is glucokinase a hexokinase?

Glucokinase (GK) belongs to the hexokinase family (Grossbard and Schimke, 1966). It catalyzes the phosphorylation of a glucose molecule to produce glucose 6-phosphate and plays an important role in glucose utilization and metabolism in the liver and pancreas (Al-Hasani et al., 2003).

What is glucokinase inhibited by?

Glucokinase is inhibited in the postabsorptive state by sequestration in the nucleus bound to GKRP, and it is activated postprandially by portal hyperglycemia and fructose through dissociation from GKRP, translocation to the cytoplasm, and binding to PFK2/FBP2.

Does hexokinase or glucokinase have a higher affinity for glucose?

Glucokinase and Hexokinase are enzymes which phosphorylate glucose to glucose-6-phosphate, trapping glucose inside the cell. ... Hexokinase is found in most tissues. Compared to glucokinase, hexokinase has a lower Km (higher binding affinity) and lower Vmax (lower capacity).