Multienzyme complex

{{short description|Protein complex for carrying out biochemical reactions}}

In molecular biology, a '''multienzyme complex''' is a protein complex containing several copies of one or more enzymes packed into one macromolecular assembly. Multienzyme complexes carry out a single or multi-step biochemical reaction taking place within cells. It allows the cell to segregate certain biochemical pathways into one place in the cell.<ref name=Trends_in_biochemical_sciences_2015>{{Cite journal|doi = 10.1016/j.tibs.2015.11.006|pmid = 26699226|volume = 41|issue = 1|pages = 1–3|last = Neuman|first = Nicole|title = The Complex Macromolecular Complex: Trends in Biochemical Sciences|journal = Trends in Biochemical Sciences|year = 2016|doi-access = free}}</ref>

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.<ref name = Ahmed1968>Ahmed A. Organization of the histidine-3 region of Neurospora. Mol Gen Genet. 1968;103(2):185-93. doi: 10.1007/BF00427145. PMID 4306011</ref> 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.<ref name = Ahmed1968/> 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.

==References== {{reflist}}

Category:Enzymes