This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzyme kinetics, Subject name: Biochemistry
Unit of Km is: 
Select and explain. 
A. second-1, B. Moles second-1, C. Millimoles, D. Millimoles Litre-1
D: Millimoles Litre-1
Answer: D: Millimoles Litre-1 
Explanation: The Km is the substrate concentration at 1/2 Vmax. As Km is the concentration, unit of Km will be the unit of concentration Km is a measure of a substrate's affinity for the enzyme. It is inversely propoional to the affinity.