1e8d: Difference between revisions

The structure and function of hydroxynitrile lyase from Manihot esculenta, (MeHNL) have been analyzed by X-ray crystallography and site-directed, mutagenesis. The crystal structure of the MeHNL-S80A mutant enzyme has, been refined to an R-factor of 18.0% against diffraction data to 2.1-A, resolution. The three-dimensional structure of the MeHNL-S80A-acetone, cyanohydrin complex was determined at 2.2-A resolution and refined to an, R-factor of 18.7%. Thr11 and Cys81 involved in substrate binding have been, substituted by Ala in site-directed mutagenesis. The kinetic measurements, of these mutant enzymes are presented. Combined with structural data, the, results support a mechanism for cyanogenesis in which His236 as a general, base abstracts a proton from Ser80, thereby allowing proton transfer from, the hydroxyl group of acetone cyanohydrin to Ser80. The His236 imidazolium, cation then facilitates the leaving of the nitrile group by proton, donating.

1E8D is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Manihot_esculenta Manihot esculenta] with CNH as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Transferred_entry:_3.3.2.4 Transferred entry: 3.3.2.4], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.37 4.2.1.37] Structure known Active Sites: ASA and ASB. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1E8D OCA].  

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