1E89

ON THE MECHANISM OF CYANOGENESIS CATALYZED BY HYDROXYNITRILE LYASE FROM MANIHOT ESCULENTA. CRYSTAL STRUCTURE OF ACTIVE SITE MUTANT SER80ALA IN COMPLEX WITH ACETONE CYANOHYDRIN

Summary for 1E89

• Entry DOI: 10.2210/pdb1e89/pdb
• Related: 1DWO 1DWP 1DWQ
• Descriptor: HYDROXYNITRILE LYASE (2 entities in total)
• Functional Keywords: lyase, hydroxynitrile lyase, active site mutant, acetone cyanohydrin complex
• Biological source: MANIHOT ESCULENTA (CASSAVA)
• Total number of polymer chains: 2
• Total formula weight: 59638.42

Authors

Lauble, H.,Miehlich, B.,Foerster, S.,Wajant, H.,Effenberger, F. (deposition date: 2000-09-18, release date: 2001-08-17, Last modification date: 2023-12-13)

Primary citation

Lauble, H.,Miehlich, B.,Foerster, S.,Wajant, H.,Effenberger, F.
Mechanistic Aspects of Cyanogenesis from Active-Site Mutant Ser80Ala of Hydroxynitrile Lyase from Manihot Esculenta in Complex with Acetone Cyanohydrin
Protein Sci., 10:1015-, 2001

PubMed Abstract: 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.

PubMed: 11316882
DOI: 10.1110/PS.01301

Experimental method

X-RAY DIFFRACTION (2.1 Å)