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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 ?
Creatine kinase isoenzyme patterns in human tissue obtained at surgery.
Characterization of the major laccase isoenzyme from Trametes pubescens and regulation of its synthesis by metal ions.
At a phenylacetate concentration of 1 mmol/L, the mean specific activities (micromoles of substrate hydrolyzed per milligram of PON1 protein) of PON1 type Q and R isoenzymes for phenylacetate (i.
The binomial distribution pattern (Fig 2) of the 28 GDH hexameric isoenzymes [7, 22] is a protein population array that displays the subunit relationships among the isoenzymes in the horizontal, vertical, and diagonal directions on the neutral acrylamide gel electrophoretic landscape.
Creatine kinase isoenzymes in extracts of various human skeletal muscles.
Methods for identifying cell lines were not limited to isoenzyme phenotypes.
The results of this In vitro metabolism study indicated that AHCC is not an inhibitor of the major CYP450 isoenzyme pathways.
brucei stocks from man and animals by isoenzyme electrophoresis (22) and polymerase chain reaction based methods have led to the identification of more mammalian hosts as reservoirs for T.
There are two kinds of isoenzymes of aspartate aminotransferase: mitochondrial aspartate aminotransferase (mAST) and cytosolic AST.
Two isoenzymes of 11beta-HSD have been characterized and cloned in human tissues.
Titan LDH (Lactate dehydrogenase) isoenzymes kits (Helena Lab.
Simplified procedure of electrophoretic separation of serum protein is the best method for the separation of isoenzymes.