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The substrate concentration midway between these two limiting cases is denoted by K M. Thus, K M is the substrate concentration at which the reaction velocity is half of the maximum velocity. [2] The two important properties of enzyme kinetics are how easily the enzyme can be saturated with a substrate, and the maximum rate it can achieve.
By increasing the substrate concentration, the rate of reaction will increase due to the likelihood that the number of enzyme-substrate complexes will increase; this occurs until the enzyme concentration becomes the limiting factor.
Increasing the substrate concentration increases the rate of reaction (enzyme activity). However, enzyme saturation limits reaction rates. An enzyme is saturated when the active sites of all the molecules are occupied most of the time. At the saturation point, the reaction will not speed up, no matter how much additional substrate is added.
To find the maximum speed of an enzymatic reaction, the substrate concentration is increased until a constant rate of product formation is seen. This is shown in the saturation curve on the right. Saturation happens because, as substrate concentration increases, more and more of the free enzyme is converted into the substrate-bound ES complex.
, known as the turnover number or catalytic constant, normally expressed in s –1, is the limiting number of substrate molecules converted to product per enzyme molecule per unit of time. Further addition of substrate would not increase the rate, and the enzyme is said to be saturated.
Increasing the substrate concentration would diminish the "competition" for the substrate to properly bind to the active site and allow a reaction to occur. [3] When the substrate is of higher concentration than the concentration of the competitive inhibitor, it is more probable that the substrate will come into contact with the enzyme's active ...
When the substrate is present within a lipid raft, sequestration leads to an increased concentration of the protein near the substrate. Conversely, if the substrate is excluded from a lipid raft, sequestration results in decreased interaction between the protein and the substrate, as seen with PLD2. Either the substrate of the enzyme can move.
In chemistry, the term "turnover number" has two distinct meanings.. In enzymology, the turnover number (k cat) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [E T] for enzymes with two or more active sites. [1]