<unk> s (also known as isoenzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction.  These enzymes usually display different kinetic parameters (i.e. different KM values), or different regulatory properties.
The existence of<unk> s 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,<unk> s (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<unk> s represent enzymes from different genes whose products catalyse the same reaction, the two words are usually used interchangeably.
Isozyme
Brinase
Elastase
Diastase
Fibrinolysin
Enzyme
Caspase
Pegaspargase