1llq
Crystal Structure of Malic Enzyme from Ascaris suum Complexed with Nicotinamide Adenine Dinucleotide
OverviewOverview
The structure of the Ascaris suum mitochondrial NAD-malic enzyme in binary complex with NAD has been solved to a resolution of 2.3 A by X-ray crystallography. The structure resembles that of the human mitochondrial enzyme determined in complex with NAD [Xu, Y., Bhargava, G., Wu, H., Loeber, G., and Tong, L. (1999) Structure 7, 877-889]. The enzyme is a tetramer comprised of subunits possessing four domains organized in an "open" structure typical of the NAD-bound form. The subunit organization, as in the human enzyme, is a dimer of dimers. The Ascaris enzyme contains 30 additional residues at its amino terminus relative to the human enzyme. These residues significantly increase the interactions that promote tetramer formation and give rise to different subunit-subunit interactions. Unlike the mammalian enzyme, the Ascaris malic enzyme is not regulated by ATP, and no ATP binding site is observed in this structure. Although the active sites of the two enzymes are similar, residues interacting with NAD differ between the two. The structure is discussed in terms of the mechanism and particularly with respect to previously obtained kinetic and site-directed mutagenesis experiments.
About this StructureAbout this Structure
1LLQ is a Single protein structure of sequence from Ascaris suum. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the malic enzyme from Ascaris suum complexed with nicotinamide adenine dinucleotide at 2.3 A resolution., Coleman DE, Rao GS, Goldsmith EJ, Cook PF, Harris BG, Biochemistry. 2002 Jun 4;41(22):6928-38. PMID:12033925 Page seeded by OCA on Sat May 3 00:02:34 2008