Question

what are cofactors that are required by enzymes

Answer 1

Many enzymes catalyze biochemical reactions as such. However,many enzymes require further components than the amino acid residues of the protein polypeptide chain for their activity. So, the active sites of a large number of enzymes require specially constructed functional groups. Such groups are provided by relatively small non protein molecules called cofactors.

Such a cofactor may be an organic molecule normally referred to as coenzyme or it may be a metal ion.

Cofactors function by providing functional groups needed for the reaction or by slightly altering the structural conformation of the enzyme to which they are bound. This alteration allows substrates to bind more easily, making a reaction more probable. Cofactors can be prosthetic groups which are tightly bound to the enzyme, or the cofactors can be coenzymes which can be loosely bound. Such an enzyme without the cofactor is called an apoenzyme; the complete catalytically active form is called a holoenzyme.