Conjugated proteins. Prosthetic groups. Coenzymes

FIGURE 25.6 Fatty acids are conjugated both to coenzyme A and to acyl carrier protein through the sulfliydryl of phosphopantetheine prosthetic groups. 

Very special proteins are called enzymes. These are biological catalysts. Their primary function is to increase the rate of reactions in organisms and they are found in all living systems. Many enzymes, like pepsin or trypsin are relatively simple proteins. Others are conjugated proteins containing prosthetic groups often known as coenzymes. Because of their extreme importance to... 

Enzymes are proteins that can catalyze certain reactions. Simple enzymes consist only of amino acid units, examples being pepsin and ribo-nuclease. Conjugated enzymes contain in addition a nonprotein (prosthetic) group, a so-called coenzyme. Enzymes are generally classified according to the type of reaction they catalyze. 

Prosthetic group a nonproteogenic, low M, group present in a conjugated protein. In an enzyme, a P.g. is a catalytically active group attached to the enzyme protein (apoenzyme). In the wide sense, P.g. are therefore Coenzymes (see), but many authors make a clear distinction, i.e. P.g. are covalently bound... 

What is an enzyme A prosthetic group A conjugated protein A coenzyme A substrate ... 

While some enzymes are composed solely of protein, others require one or more non-protein substances of low molecular weight for their activity. If the non-protein moiety is firmly bound to the protein part it is known as a prosthetic group and the protein is a conjugated protein-, but where the enzyme is only active in the presence of a discrete small organic molecule, separable by dialysis, the non-protein substance is known as a coenzyme. 

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