7aat
X-RAY STRUCTURE REFINEMENT AND COMPARISON OF THREE FORMS OF MITOCHONDRIAL ASPARTATE AMINOTRANSFERASE
Structural highlights
FunctionAATM_CHICK Catalyzes the irreversible transamination of the L-tryptophan metabolite L-kynurenine to form kynurenic acid (KA). Plays a key role in amino acid metabolism. Important for metabolite exchange between mitochondria and cytosol. May facilitate cellular uptake of long-chain free fatty acids (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe X-ray crystal structures of three forms of the enzyme aspartate aminotransferase (EC 2.6.1.1) from chicken heart mitochondria have been refined by least-squares methods: holoenzyme with the co-factor pyridoxal-5'-phosphate bound at pH 7.5 (1.9 A resolution), holoenzyme with pyridoxal-5'-phosphate bound at pH 5.1 (2.3 A resolution) and holoenzyme with the co-factor pyridoxamine-5'-phosphate bound at pH 7.5 (2.2 A resolution). The crystallographic agreement factors [formula: see text] for the structures are 0.166, 0.130 and 0.131, respectively, for all data in the resolution range from 10.0 A to the limit of diffraction for each structure. The secondary, super-secondary and domain structures of the pyridoxal-phosphate holoenzyme at pH 7.5 are described in detail. The surface area of the interface between the monomer subunits of this dimeric alpha 2 protein is unusually large, indicating a very stable dimer. This is consistent with biochemical data. Both subunit and domain interfaces are relatively smooth compared with other proteins. The interactions of the protein with its co-factor are described and compared among the three structures. Observed changes in co-factor conformation may be related to spectral changes and the energetics of the catalytic reaction. Small but significant adjustments of the protein to changes in co-factor conformation are seen. These adjustments may be accommodated by small rigid-body shifts of secondary structural elements, and by packing defects in the protein core. X-ray structure refinement and comparison of three forms of mitochondrial aspartate aminotransferase.,McPhalen CA, Vincent MG, Jansonius JN J Mol Biol. 1992 May 20;225(2):495-517. PMID:1593633[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences | ||||||||||||||||||||
