Properties of Enzymes
Properties of Enzymes include,
a) Catalytic Property
b) Specificity
c) Active nature in minute quantity
d) Reversibility
e) Thermolability
f) Sensitivity to pH
g) Proteinaceous nature
a) Catalytic Property
An enzyme is an organic catalyst. As enzymes participate in biological reaction, they are also called biocatalysts. Enzymes associate with the substrates and form an enzyme-substrate complex. At the end of the reaction, the substrate is converted to products and the enzyme is released. Enzyme remains unchanged at the end of the reaction catalyzed by it. It only speeds up a rate of a reaction and never changes the equilibrium of a reaction.
b) Specificity
Enzymes are reaction specific. One enzyme catalyzes only one specific reaction or acts on a particular substrate. For example, enzyme sucrose catalyzes the hydrolysis of only sucrose and no other substrate.
c) Active in Minute Quantity
Enzymes are active in extremely small quantities. The number of substrate molecules converted into products by one molecule of an enzyme in one minute time is called turn over number (TON). For example, if one molecule of sucrase can convert 100 molecules of sucrose in one minute, the TON of sucrase is 100. This varies from enzyme to enzyme. The TON of any enzymes is constant.
d) Reversibility
Most enzymes are reversible in their action. They can speed up a particular reaction either in forward or in backward direction. For example, the enzyme aldolase converts a hexose into two trioses, and the same enzyme forms a hexose from two trioses.
Hexose (6C) □(↔┴( Aldolase ) ) Triose (3C)+Triose (3C)
e) Thermolability
Enzymes are heat sensitive. At low temperatures they are temporarily inactivated. Very cold temperatures in a refrigerator, keeps the enzyme in a temporarily inactive state. Food is not spoiled because neither microbial enzymes nor the enzymes in the food can act at low temperatures to cause it spoilage.
At high temperature they get denatured, because enzymes are chemically proteins. The optimum temperature for most of enzymes is within the range of 25°-30°C.
f) Sensitivity to pH
They hydrogen ion concentration controls the enzymatic activity to a great extent. Most of the enzymes, work at their best in neutral pH. However some enzymes work in acidic medium while others require an alkaline medium to function.
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