What is the use of sulphuric acid in the enzyme reaction?

Question

enzyme from cow's liver extract

Answer 1

Catalysis is an acceleration or retardation of the rate of a chemical reaction, brought about by the addition of a substance (the catalyst) to the reaction medium. The catalyst, usually present in small amounts, is not consumed in the reaction. Catalysis today is almost always associated with rate acceleration, and is very important in industry because rate acceleration usually means that a chemical compound can be made more cheaply and cleanly. It is hard to envision what modern society would be like without its use of myriad chemicals, polymers, and pharmaceuticals, most of which are prepared industrially by catalytic chemistry.

The rate of reaction refers to the amount of reactant consumed or product formed per unit of time at a given temperature and pressure. Generally speaking, the rate of reaction goes up as the temperature of the reaction is raised. This is related to the fact that most reactants have to "climb" over one or more energy barriers to reach the product stage. This can be likened to one's climbing a hill. The taller the hill, the more energy one expends in reaching its top. Reactants must become energetic enough to "reach" the top of an energy barrier if a reaction is to occur. Raising the reaction temperature ultimately imparts more energy to the reactants, creating a greater probability that more of them will be energetic enough to traverse the barrier, and this results in a faster rate.

What does a catalyst do? First of all, a catalyst does not change the energetic characteristics of the reactants and products and the barriers between them. It instead finds an alternate reaction pathway that bridges reactants and products, and one that has lower (and thus easier-to-traverse) energy barriers. An alternate pathway means a faster reaction rate. Although a catalyst can itself be considered a reactant, it is regenerated, unchanged, at a later stage in the catalytic process. The regenerated catalyst can then be used to catalyze another like reaction. Thus, in principle, only a very small amount of catalyst is needed to generate copious amounts of product. This is desirable, as many catalysts that are used industrially are very expensive.

Homogeneous catalysis refers to catalytic reactions in which the catalyst is in the same phase as the reactant. This is most often the liquid phase, although gas phase examples are known. Ozone in the stratosphere, for example, is converted into oxygen via the catalytic action of chlorine atoms formed as a result of the photochemical destruction of chlorofluorocarbon refrigerants.

The Fischer esterification, named after the eminent German chemist Emil Fischer, is the Brønsted acid–catalyzed reaction of an alcohol with a carboxylic acid to form an ester (see Table 1). Sulfuric acid is often the catalyst. Esters are widely used in the soap, perfume, and food industries.