What is the effect of substrate concentration on enzyme activity? How does enzyme activity change as substrate concentration decreases? Explain on a molecular basis.

I am not sure what the question wants from me. Would this be right, and is there anything missing from my response? :: As the substrate concentration increases, the rate of reaction also increases. This is because more of the substrate is available to allow the enzyme to bind to it.

or wait..is it because if more substrate is available, then reactions will occur faster? I need some help wording this, please :)

Your response is partially correct, but there are some additional details you can include.

The effect of substrate concentration on enzyme activity is generally described by the Michaelis-Menten equation. According to this equation, the initial reaction rate (V0) increases with increasing substrate concentration up to a certain point, after which it levels off due to the saturation of available enzyme molecules with substrate.

At low substrate concentrations, the enzyme molecules have a high probability of being vacant, and as a result, the binding of substrate molecules to the active sites is relatively fast. This leads to an increase in the rate of reaction as substrate concentration increases. However, as the substrate concentration increases further, the active sites become increasingly occupied, which reduces the rate at which additional substrate molecules can bind to the enzymes.

At the point of saturation, all active sites of the enzyme are occupied by substrate molecules, and the enzyme reaches its maximum rate of reaction, known as Vmax. From this point onwards, further increases in substrate concentration will have no effect on the reaction rate, as all the enzyme molecules are already utilized.

On a molecular basis, when the substrate concentration is low, there are more empty active sites available for the substrate to bind to. This allows for more frequent collisions between the enzyme and substrate, leading to an increased rate of formation of the enzyme-substrate complex and higher reaction rates. As the substrate concentration decreases, there are fewer collisions, resulting in a reduction in enzyme activity.

It is important to note that this response provides a general overview, and the behavior of enzyme activity in relation to substrate concentration can slightly vary for different enzymes.

Your response is partially correct, but let me provide a more comprehensive explanation.

The effect of substrate concentration on enzyme activity can be described by the theory known as the Michaelis-Menten kinetics. According to this theory, enzyme activity is generally dependent on the concentration of the substrate.

As the substrate concentration increases, there is an initial rapid increase in the enzyme activity, known as the initial velocity or V0. This is because a higher substrate concentration means more substrate molecules are available for the enzyme to bind to. Therefore, enzyme-substrate collisions occur more frequently, resulting in a greater number of successful enzyme-substrate complex formations and, consequently, a higher rate of reaction.

However, there is a point at which increasing the substrate concentration no longer significantly affects the reaction rate. This occurs when the enzyme becomes saturated with substrate molecules, meaning all enzyme active sites are continuously occupied by substrates. At this point, the reaction rate reaches its maximum point, known as Vmax. Further increase in substrate concentration beyond this point does not cause any further increase in the reaction rate.

On the other hand, if the substrate concentration decreases, the enzyme activity will also decrease. This is because fewer substrate molecules are available for the enzyme to bind to, resulting in fewer successful enzyme-substrate complex formations and a lower rate of reaction.

At extremely low substrate concentrations, the enzyme activity may not be noticeable or may even reach a point where it becomes undetectable. This is because the probability of enzyme-substrate collisions decreases, reducing the frequency of successful enzyme-substrate complex formations.

To summarize, as substrate concentration decreases, enzyme activity decreases due to a decrease in the number of collisions between enzyme and substrate molecules. This decrease in enzyme activity occurs on a molecular basis, based on the principles of enzyme-substrate complex formation and the concept of molecular collision theory.