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isozymes, different structural forms of enzymes with a single type of catalytic activity in organisms of the same species (or tissue).

Isoenzymes catalyze the same reaction but differ in amino acid composition and in some of their physical, immunological, and catalytic properties. Isoenzymes consist of several polypeptide chains (subunits), combined in various ways to form a quaternary enzyme structure. Thus, two forms of the lactate dehydrogenase enzyme are found in the chick—one characteristic of skeletal muscles, the other of heart muscle. In all, five isoforms of this enzyme have been found in chicks and other organisms, each form (tetramer) made up of four protein subunits of two types. Electrophoresis can be used to separate isoenzymes. In organisms of the same species (or in the same tissue), isoenzymes form a characteristic set, or spectrum, which may be altered with pathological tissue changes (useful in diagnosis) and in the process of ontogeny.


Wilkinson, G. Izofermenty. Moscow, 1968. (Translated from the English.)


References in periodicals archive ?
Rest three isoenzymes were isolated from coleoptile using extraction buffer (0.
Different garlic preparations have shown diverse and highly variable results of the effects of CYP isoenzymes and metabolism
20, in both types of cysts was observed in the esterase isoenzyme pattern; the esterase in the white cysts showed a darker band and exhibited more activity than the esterase in the brown cysts.
Objective: To determine the levels of serum lactate dehydrogenase 2 (LD2) Isoenzyme and b2 microglobulin (b2m) in patients of non-Hodgkin's lymphoma (NHL) and to correlate these levels in NHL patients with and without bone marrow infiltration.
Various studies have reported that autoantibodies to CA isoenzymes increase during the course of some immunological diseases.
CP is a multigene family, which consists of several related enzymes, including isoenzymes involved in four hydroxylations Lu and West (1980).
Adenosine deaminase activity and its isoenzymes in the sputum of patients with pulmonary tuberculosis.
There are 3 main isoenzymes of CK: CK-MM, CK-MB, and CK-BB, with characteristic distribution in different tissues.
Genetic polymorphism of the cytochrome P-450 isoenzymes can affect clopidogrel metabolism.
Ramponi, In Proceedings of the 40th National Congress of the Societa Italiana di Biochemica, Torino, Volume 6, Purification and some properties of two low Mr PTPase isoenzymes from Uromastix hardwickii, p.
13] Patients with intact CYP 2C19 and CYP 2D6 isoenzymes metabolized the drug normally and are considered as extensive metabolizers.
In addition, testosterone production through an alternative pathway catalyzed by other 17-(3-HSD isoenzymes may contribute to the androgenization of these structures.