Iso-enzymes are enzymes that have a different amino acid sequence than regular enzymes, but have the same biochemical function. These enzymes usually differ from kinetic parameters (i.e., KM values or VMax), or different regulatory properties. An isoenzyme is usually caused by a mutation in the original gene. An example of an isoenzyme is lactic dehydrogenase (LDH), which is a tetramer consisting of a combination of two different monomers. Another example of an isoenzyme is glucokinase, a variant of hexokinase not inhibited by glucose-6-phosphate.
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