In the liver, the enzyme glucokinase and, in the brain, the enzyme hexokinase both catalyse the phosphorylation of glucose: $\text{glucose} + \text{ATP} \rightarrow \text{glucose phosphate} + \text{ADP}$ The activity of each enzyme was recorded at a range of glucose concentrations. The graph presents the results. What describes the different activities of the two enzymes?
- ABoth enzymes hold glucose and ATP molecules together at the active site.
- BGlucokinase becomes saturated with glucose at a lower concentration of glucose than hexokinase.
- CGlucokinase phosphorylates more molecules of glucose per minute.
- DThe affinity of hexokinase for glucose is greater than that of glucokinase.