ABSTRACT
This chapter discusses some cofactors under the general groupings of coenzymes, prosthetic groups, and inorganic ions. Many enzymes, on hydrolysis, give only amino acids; therefore, their catalytic properties must reside in a unique arrangement of amino acid residues. Other enzymes contain, in addition to the polypeptide chains, small molecules that are essential for activity of the enzyme. With prosthetic groups, the repetitive cycle is performed while the cofactor is attached tightly to one enzyme. The best method of assigning the organic cofactors to one of the two groups is on the basis of the mechanism involved in their repetitive turnover in the functioning system. Vitamins and essential trace metals are integral parts of cofactors. Recognition that thiamine performs its role as a part of a cofactor came in 1937 through work of Lohmann and Schuster. The pyridine coenzymes are essential cofactors for a number of enzymes involved in the oxidation and reduction of substrates by the transfer of hydrogen.
