isoensüümi

An isoenzyme, also known as an isozyme or allozyme, is one of several different molecular forms of an enzyme that catalyze the same biochemical reaction. Isoenzymes can differ from each other in their amino acid sequence, which can lead to variations in their physical properties such asoelectric point, substrate affinity, and inhibition patterns. These differences in structure and function allow isoenzymes to be expressed in different tissues or at different developmental stages, or to respond to different regulatory signals.

The existence of isoenzymes provides a mechanism for fine-tuning metabolic pathways. For example, different isoenzymes of lactate dehydrogenase (LDH) are found in different tissues, such as heart muscle and skeletal muscle. The heart isoenzyme has a higher affinity for its substrate and is more resistant to inhibition by pyruvate, which is consistent with its role in aerobic respiration. In contrast, the skeletal muscle isoenzyme has a lower affinity for substrate and is more easily inhibited by pyruvate, which is suited for anaerobic conditions during intense exercise.

The study of isoenzymes is important in various fields, including molecular biology, biochemistry, and medicine. Identifying and characterizing specific isoenzymes can be useful for diagnosing diseases, as the levels or activities of certain isoenzymes can be altered in pathological conditions. For instance, elevated levels of certain LDH isoenzymes in the blood can indicate tissue damage, such as a heart attack or liver disease. Genetic variations in isoenzyme genes can also contribute to individual differences in enzyme activity and metabolic traits.