Isozymes (also known as
isoenzymes or more generally as
Multiple forms of enzymes) are
enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters (e.g. different
KM values), or different regulatory properties. The existence of isozymes permits the fine-tuning of metabolism to meet the particular needs of a given tissue or developmental stage (for example
lactate dehydrogenase (LDH)). In
biochemistry, isozymes (or isoenzymes) are
isoforms (closely related variants) of enzymes. In many cases, they are coded for by
homologous genes that have diverged over time. Although, strictly speaking,
allozymes represent enzymes from different
alleles of the same
gene, and isozymes represent enzymes from different genes that process or
catalyse the same reaction, the two words are usually used interchangeably.