Glucokinase is a homodimeric enzyme that has a glucose bindi

Glucokinase is a homodimeric enzyme that has a glucose binding site in each identical monomer. The K_D of the first glucose binding event is 1 mM, but the K_D for the second event is 10 mu M. What specific type of ligand binding is occurring? Sketch a binding curve for glucose binding to glucokinase (shape only, no values). Imagine a mutation that disrupts the dimer interface causing loss of quaternary structure but has no effect on the glucose binding site itself. Sketch a binding curve for glucose binding to the mutant glucokinase (shape only, no values).

Solution

A. Hexo kinase ligand binding pattern is Cooperation binding. It is due to, the first glucose molecule bind to hexokinase at high concentration I.e 1 mM. After binding it, the glucose modify the hexokinase and allow it to bind the next glucose molecule in very low concentration even. I.e. 10 uM. So this is called Cooperative binding mechanism observed in case of Oxygen bind to Hemoglobin

B. Sigmoid type of curve can observed when we plot the graph between x-axis (Glucose concentration), y-axis (Affinity between enzyme and substrate).

C. If quaternary structure loose, then the enzyme show hyper bolic curve like that of Michales and mentons when plot graph between x-axis and y-axis