Enzymes and their Activators

Enzymes are proteins that consist of sequences of amino acids gathered together by peptide bonds. An enzyme molecule may contain one or more peptide bond or polypeptide chains. The sequence of amino acids inside the polypeptide chains is specific for each enzyme and is believed to establish the unique three-dimensional structure in which the chains are composed.

This conformation, which is essential for the functionality of the enzyme, is determined by interactions of amino acids in different zones of the peptide chains with each other and with the nearby medium. These interactions are somewhat weak and may be disrupted readily by high temperatures, acid or alkaline conditions, or changes in the polarity of the medium. These changes produce an unfolding of the peptide chains (or denaturation) and a subsequent loss of enzymatic activity, solubility, and other abilities characteristic of the original enzyme.

Many enzymes contain an extra, nonprotein component, called a coenzyme. This may be an organic molecule, often a vitamin by-product, a metal ion (copper and zinc for some of the enzymes in snail secretions) or an organic (usually metal-containing) group.

The coenzyme, in most instances, participates directly in the catalytic reaction. For example, it may act as an intermediate carrier of a group being carried from one substrate to another. Some enzymes have coenzymes that are tightly linked to the protein and difficult to eliminate, while others have coenzymes that dissociate readily. When the protein unit and the coenzyme are separated from each other, neither conserves the catalytic abilities of the original conjugated protein (the holoenzyme).

By simply mixing the protein unit and the coenzyme together, the fully active holoenzyme can usually be reconstituted. The same coenzyme may be associated with many enzymes which catalyze different reactions. It is thus mainly the nature of the protein unit rather than that of the coenzyme which determines the specificity of the reaction.

The enzyme-cofactor combination provides an active configuration, usually including an active site into which the substance (substrate) implied in the reaction can fit. Many enzymes are specific to one substrate. If a competing molecule blocks the active site or changes its shape, the enzyme’s action is inhibited. If the enzyme’s composition is destroyed its activity is lost.

Enzymes are classified by the type of reaction they accelerate: (1) oxidation-reduction, (2) change of a chemical group, (3) hydrolysis, (4) removal or addition of a chemical radical, (5) isomerization, and (6) joining together of substrate units (polymerization).

Enzymes accelerate all aspects of cellular metabolism, including the digestion of food, in which large nutrient molecules (including proteins, carbohydrates, and fats) are divided into smaller molecules; the conservation and transformation of chemical energy; and the creation of cellular elements and components.

The fermentation of wine, leavening of bread, curdling of milk into cheese, and brewing of beer are all enzymatic reactions. The uses of enzymes in medicine include destroying disease-causing microbes, the treatment of wounds, and diagnosing some diseases.

Thanks to enzymatic processes, science has been able to derive new treatments that can help repair damaged skin.

A new skin moisturizer offers the chance to get rid of scars, imperfections and several skin conditions thanks to a natural ingredient that repairs damaged tissue.

- Kathleen LeRoi