Related Experiment Video
Updated: Jul 3, 2026

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
Crystallization and preliminary X-ray diffraction experiments of arylmalonate decarboxylase from Alcaligenes
Masayoshi Nakasako1, Rika Obata, Ryosuke Okubo
1Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Kanagawa 223-8522, Japan. nakasako@phys.keio.ac.jp
Abstract:
Arylmalonate decarboxylase catalyses the enantioselective decarboxylation of alpha-aryl-alpha-methylmalonates to produce optically pure alpha-arylpropionates. The enzyme was crystallized with ammonium sulfate under alkaline pH conditions with the aim of understanding the mechanism of the enantioselective reaction. X-ray diffraction data collected to a resolution of 3.0 A at cryogenic temperature showed that the crystals belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 83.13, b = 99.62, c = 139.64 A. This suggested that the asymmetric unit would contain between four and six molecules. Small-angle X-ray scattering revealed that the enzyme exists as a monomer in solution. Thus, the assembly of molecules in the asymmetric unit was likely to have been induced during the crystallization process.
Related Concept Videos
Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives
Determination of Crystal Structures
Alkylation of β-Diester Enolates: Malonic Ester Synthesis
X-ray Diffraction of Biological Samples
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...

