At a constant enzyme concentration, the rate of an enzymatic reaction is directly influenced by the concentration of the substrate. Initially, when the substrate concentration is low, the reaction rate increases almost linearly with an increase in substrate because there are plenty of active sites available on enzyme molecules for substrate binding. Each enzyme molecule can bind to a substrate molecule without competition, resulting in a proportional increase in reaction rate. As the substrate concentration continues to rise, more enzyme active sites are occupied, and the rate of reaction increases but at a slower pace. Eventually, a point is reached where virtually all active sites are occupied by substrate molecules. At this saturation point, increasing substrate concentration further does not increase the reaction rate because the enzymes are working at their maximum capacity, a phenomenon described by Michaelis-Menten kinetics. The maximum reaction rate achieved under these conditions is termed Vmax, and the substrate concentration at which the reaction rate is half of