3C6X: HNL from Hevea brasiliensis to atomic resolution

Hydroxynitrile lyases are versatile enzymes that enantiospecifically cope with cyanohydrins, important intermediates in the production of various agrochemicals or pharmaceuticals. We determined four atomic resolution crystal structures of hydroxynitrile lyase from Hevea brasiliensis: one native and three complexes with acetone, isopropyl alcohol, and thiocyanate. We observed distinct distance changes among the active site residues related to proton shifts upon substrate binding. The combined use of crystallography and ab initio quantum chemical calculations allowed the determination of the protonation states in the enzyme active site. We show that His(235) of the catalytic triad must be protonated in order for catalysis to proceed, and we could reproduce the cyanohydrin synthesis in ab initio calculations. We also found evidence for the considerable pK(a) shifts that had been hypothesized earlier. We envision that this knowledge can be used to enhance the catalytic properties and the stability of the enzyme for industrial production of enantiomerically pure cyanohydrins.
PDB ID: 3C6XDownload
MMDB ID: 64779
PDB Deposition Date: 2008/2/6
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.05  Å
Source Organism:
Similar Structures:
Biological Unit for 3C6X: dimeric; determined by author and by software (PISA)
Molecular Components in 3C6X
Label Count Molecule
Proteins (2 molecules)
Molecule annotation
Chemicals (14 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB