BIOLOGY Volume 1 - A Guide to General Biology - 2004

4. ENZYMES

4.5. Enzyme Cofactors

Many Enzymes require certain non-protein components known as Cofactors for their efficient function. Cofactors are substances whose presence is absolutely essential for the manifestation of catalytic activity in enzymes, although, unlike enzymes themselves, they remain stable at relatively high temperatures. The Role of cofactors can be played by various substances—ranging from simple inorganic ions to complex organic molecules; in some cases, they remain unchanged at the end of the reaction, while in others, they are regenerated through a subsequent process. Cofactors are subdivided into three types: inorganic ions, prosthetic groups, and Coenzymes. These will be discussed in the next three sections.

4.5.1. Inorganic Ions (Enzyme Activators)

It is believed that these ions induce the enzyme or substrate molecules to adopt a conformation that facilitates The formation of the enzyme-substrate complex. This increases the probability that the enzyme and substrate will actually react with each other and, consequently, enhances The rate of the reaction catalyzed by the given enzyme. For example, The activity of salivary amylase is increased in the presence of chloride ions.