1e89: Difference between revisions

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==Overview==

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.

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.

==About this Structure==

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[[Category: Manihot esculenta]]

[[Category: Single protein]]

[[Category: Transferred entry: 3.3.2.4]]

[[Category: Transferred entry: 3 3.2 4]]

[[Category: Effenberger, F.]]

[[Category: Foerster, S.]]

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[[Category: hydroxynitrile lyase]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-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.
+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.
 ==About this Structure==
@@ Line 13: / Line 13: @@
 [[Category: Manihot esculenta]]
 [[Category: Single protein]]
-[[Category: Transferred entry: 3.3.2.4]]
+[[Category: Transferred entry: 3 3.2 4]]
 [[Category: Effenberger, F.]]
 [[Category: Foerster, S.]]
@@ Line 23: / Line 23: @@
 [[Category: hydroxynitrile lyase]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb  3 09:38:12 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:24:54 2008''