Isoenzymes

1. Multiple Forms of Enzymes and the Emergence of the Isoenzyme Concept.- 2. Origins and Structures of Multiple Forms of Enzymes.- Origins of isoenzymes.- Isoenzymes determined by multiple gene loci.- Isoenzymes determined by multiple alleles.- Hybrid isoenzymes.- Structural differences between isoenzymes and their investigation.- Differences in primary structure.- Peptide maps and partial sequences.- Selective chemical or enzymic modification.- Secondary and tertiary structures.- Quaternary structure.- Non-isoenzymic multiple forms of enzymes.- Variations in covalent structures.- Variations in non-polypeptide constituents.- Non-covalent modifications of enzyme structure.- 3. Differences in Properties between Multiple Forms of Enzymes.- Catalytic differences between multiple forms of enzymes.- Differences in specific activity.- Differences in reaction with substrates.- Selective inhibition of isoenzymes.- Differences between isoenzymes in other catalytic properties.- Physicochemical differences between multiple forms of enzymes.- Differences in ionic characteristics.- Differences in stability.- Differences in molecular size.- Immunochemical differences between multiple forms of enzymes.- Immunoanalytical procedures useful in studies of multiple forms of enzymes.- Properties of multiple forms of enzymes: general considerations.- Differences in catalytic properties.- Differences in antigenicity.- Differences in resistance to inactivation.- Differences in charge or size.- 4. Distribution and Biological Functions of Multiple Forms of Enzymes.- Distribution of enzymes determined by multiple gene loci.- Intracellular distribution of isoenzymes.- Effect of multiple allelism on isoenzyme distribution.- Physiological function of multiple forms of enzymes.- Compartmentalization of metabolic pathways in tissues and organelles.- Functions of other multiple forms of enzymes.- 5. Multiple Forms of Enzymes in Phylogeny and Genetics.- Gene duplication and the evolution of multiple loci.- Isoenzymes of lactate dehydrogenase in various species.- Widely-distributed multiple forms of other enzymes.- Genetics of isoenzymes.- Isoenzymes and genetic disease.- Chromosomal assignments of enzyme-determining genes.- 6. Multiple Forms of Enzymes in Ontogeny.- Changes during normal development.- Isoenzymes determined by multiple gene loci.- Developmental changes in isoenzymes in plants.- Developmental changes in multiple forms of enzymes due to post genetic modifications.- Changes associated with abnormal development.- Changes associated with malignant transformation.- Selective induction of isoenzymes.- 7. Multiple Forms of Enzymes in Diagnostic Enzymology.- Lactate dehydrogenase isoenzymes.- Creatine kinase isoenzymes.- Multiple forms of alkaline phosphatase.- Acid phosphatase isoenzymes.- Other isoenzymes.- References.