2pan
Crystal structure of E. coli glyoxylate carboligase
OverviewOverview
Thiamine diphosphate (ThDP), a derivative of vitamin B1, is an enzymatic cofactor whose special chemical properties allow it to play critical mechanistic roles in a number of essential metabolic enzymes. It has been assumed that all ThDP-dependent enzymes exploit a polar interaction between a strictly conserved glutamate and the N1' of the ThDP moiety. The crystal structure of glyoxylate carboligase challenges this paradigm by revealing that valine replaces the conserved glutamate. Through kinetic, spectroscopic and site-directed mutagenesis studies, we show that although this extreme change lowers the rate of the initial step of the enzymatic reaction, it ensures efficient progress through subsequent steps. Glyoxylate carboligase thus provides a unique illustration of the fine tuning between catalytic stages imposed during evolution on enzymes catalyzing multistep processes.
About this StructureAbout this Structure
2PAN is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Glyoxylate carboligase lacks the canonical active site glutamate of thiamine-dependent enzymes., Kaplun A, Binshtein E, Vyazmensky M, Steinmetz A, Barak Z, Chipman DM, Tittmann K, Shaanan B, Nat Chem Biol. 2008 Feb;4(2):113-8. Epub 2008 Jan 6. PMID:18176558 Page seeded by OCA on Sun May 4 12:44:30 2008