Nature Of Enzymes

Nature of Enzyme

Isoenzyme has slightly different molecular structures but exerts similar catalytic actions. E.g., Lactic, LHD.
Cofactors are non-protein substances which associate with the enzyme. It is only in the presence of cofactors that some enzymes can exhibit their catalytic activities, e.g., Mg++ ions.
An enzyme that functions only in the presence of cofactors is called apoenzyme. If the co-factor is an organic compound that can be easily separated from apoenzyme, it is called a coenzyme. If the co-factors are bound with the enzyme, it is called a prosthetic group. A combination of an apoenzyme and its cofactor is called a holoenzyme.
All enzyme has a specific three-dimensional structure; a part of it is known as active sites into which substrate fits. The point where a substitute is bound on the active sites is known as the substrate-binding site.
Mostly enzyme functions between 25-40ºC and a particular pH.

Figure: Effective of temperature on the enzyme

Figure: Effective of pH on the enzyme.

The number of substrate molecules converted to products per minute by enzyme molecule is called the turn over number. This exhibits the efficiency of an enzyme.