Unstable mutants and molecular hybrids in enzyme deficiency conditions.

Multiple molecular forms contribute to various types of enzyme heterogeneity: "Iso(en)-zymes" and "Allozymes" (enzyme variants) are of genetic origin whereas "Metazymes" represent secondary modifications of epigenetic nature. The concept of variability originates from the discovery of a large number of enzyme variants. Structural gene mutations can lead to enzyme variants of low specific activity or reduced stability and can cause enzyme deficiencies. In heterozygous carriers of oligomeric enzyme defects, the formation of hybrid molecules is possible by random assembly of simultaneously synthetized normal and mutant subunits. The study of normal processes as well as enzyme anomalies contributes essentially to better understanding of biochemical individuality and evolutionary events at a molecular level.