Abstract
In a previous study, we reported the apparent similarity between a low resolution electron density map of mitochondrial malate dehydrogenase and a model of cytoplasmic malate dehydrogenase (Roderick, S. L., and Banaszak, L. J. (1983) J. Biol. Chem. 258, 11636-11642). We have since determined the polypeptide chain conformation and coenzyme binding site of crystalline porcine heart mitochondrial malate dehydrogenase by x-ray diffraction methods. The crystals from which the diffraction data was obtained contain four subunits of the enzyme arranged as a "dimer of dimers," resulting in a crystalline tetramer which possesses 222 molecular symmetry. The overall polypeptide chain conformation of the enzyme, the location of the coenzyme binding site, and the preliminary location of several catalytically important residues have confirmed the structural similarity of mitochondrial malate dehydrogenase to cytoplasmic malate dehydrogenase and lactate dehydrogenase.
Highlights
From the Department of Biological Chemistry, Division of Biology and Biomedical Sciences, Washington University, St
The overall polypeptide chain conformation of the enzyme, the location the coenzyme binding site, and the preliminary locagenase, and an“x-ray” sequence of porcine heart cytoplasmic malate dehydrogenase indicated that the malate and lactate dehydrogenases are only about 20-25% homologous, a number of residues are absolutely conserved (Birktoft et al, oft1h9o8u2gah).tAtmo ocnogmtphreissee are ahistidine and aspartic acid residue a proton relay system from the 2-hytion of several catalytically important residues have droxyl oxygen of the reduced substrate to thehistidine imidaconfirmed the structural similarity of mitochondrial zole ring andan arginine residue whichmayserve asa malate dehydrogenase to cytoplasmic malate dehydro-counterion to the 1-carboxylate group of the substrate
We described the similarity of an cycarbon model of cytoplasmic malate dehydrogenase toan electron density map of porcine heart mitochondrial malate (Roderickand Banaszak, 1983).The interpretation of electron density maps at higher resolution presented in this report has resulted in an a-carbon model of mitochondrial malate dehydrogenase and a more precise representation of the coenzyme binding site
Summary
Larity between a low resolution electron density map The subunits of tetrameric lactate dehydrogenase are reof mitochondrial malate dehydrogenase aandmodel of lated by three mutually perpendicular and intersecting 2-fold cytoplasmicmalatedehydrogenase(Roderick, S. Heavy atom derivative crystals were prepared as in thelow resolution study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
