Enzyme Structure and Functions:

Topics: Enzyme, Chemical reaction, Catalysis Pages: 4 (906 words) Published: November 19, 2012

Enzymes are biological catalysts. They increase the rate of reactions by a factor of between 106 to 1012 times, allowing the chemical reactions that make life possible to take place at normal temperatures Definition of enzyme:

A protein with catalytic properties due to its power of specific activation is defined as an enzyme.

Enzymes are proteins their function depends on its complexity. The reaction takes place in a small part of the enzyme called the active site, while the rest of the protein acts as "scaffolding". The shape and the chemical environment inside the active site permits a chemical reaction to proceed more easily Many enzymes need cofactors (or coenzymes) to work properly. Tightly bound cofactors are called prosthetic groups

Cofactors that are bound and released easily are called coenzymes These can be metal ions (such as Fe2+, Mg2+, Cu2+) or organic molecules (such as haem, biotin, FAD, NAD or coenzyme A). Many of these are derived from dietary vitamins, which is why they are so important. The complete active enzyme with its cofactor is called a holoenzyme, while just the protein part without its cofactor is called the apoenzyme. HW DOES AN ENZYME WORK?


In any chemical reaction, a substrate (S) is converted into a product (P) In an enzyme-catalysed reaction, the substrate first binds to the active site of the enzyme to form an enzyme-substrate (ES) complex, then the substrate is converted into product whilst attached to the enzyme, and finally the product is released, thus allowing the enzyme to start all over again An example is the action of the enzyme sucrase hydrolysing sucrose into glucose and fructose.

The substrate molecule is complementary in shape to that of the active site. It was thought that the substrate exactly fitted into the active site of the enzyme molecule like a key fitting...
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