Multienzyme complex contains several copies of one or several enzymes (polypeptide chains) packed into one assembly. Multienzyme complex carries out a single or a series of biochemical reactions taking place in the cells. It allows to segregate certain biochemical pathways into one place in the cell.[1]
Examples include pyruvate dehydrogenase, fatty acid synthetase, glutamine synthetase, proteasome, rubisco.
A multienzyme complex that functions in the histidine biosynthesis pathway has been studied at the biochemical and genetic level in the fungus Neurospora crassa. A gene (His-3) was found to encode a protein that functions as a multienzyme complex having three distinct enzymatic activities in the biosynthesis pathway.[2] A genetic analysis of mutants defective in the N. crassa histidine pathway indicated that the individual activities of the multienzyme complex occur in discrete regions of the His-3 genetic map. This finding suggested that each of the activities of the multienzyme complex are encoded separately from each other, but within the same gene.[2] Some His-3 mutants were also found that lacked all three activities simultaneously, suggesting that some mutations can cause loss of function of the whole multienzyme complex.