Other Crystal Forms (other + crystal_form)

Distribution by Scientific Domains

Selected Abstracts

The structure of the hexagonal crystal form of hen egg-white lysozyme

M. S. Weiss
The three-dimensional structure of hen egg-white lysozyme (HEWL) in a hexagonal crystal form has been determined and refined to 1.46, resolution. This hexagonal crystal form crystallizes from a saturated sodium nitrate solution at pH 8.4. The crystals belong to space group P6122, with unit-cell parameters a = b = 85.64, c = 67.93,. A total of 165 water molecules, 16 nitrate ions and five sodium ions were located in the electron-density map. The hexagonal crystal form exhibits a higher solvent content and a higher degree of disorder than other crystal forms of lysozyme. The flexibility of the protein depends on the crystal packing, although some residue ranges are flexible in all native HEWL crystal forms. [source]

Structure of a new `aspzincin' metalloendopeptidase from Grifola frondosa: implications for the catalytic mechanism and substrate specificity based on several different crystal forms

Tetsuya Hori
Crystal structures of a peptidyl-Lys metalloendopeptidase (MEP) from the edible mushroom Grifola frondosa (GfMEP) were solved in four crystal forms. This represents the first structure of the new family `aspzincins' with a novel active-site architecture. The active site is composed of two helices and a loop region and includes the HExxH and GTxDxxYG motifs conserved among aspzincins. His117, His121 and Asp130 coordinate to the catalytic zinc ligands. An electrostatically negative region composed of Asp154 and Glu157 attracts a positively charged Lys side chain of a substrate in a specific manner. A Tyr133 side chain located on the S1, pocket had different configurations in two crystal forms and was not observed in the other crystal forms. The flexible Tyr133 plays two roles in the enzymatic function of GfMEP. The first is to provide a hydrophobic environment with Phe83 in order to accommodate the alkyl part of the Lys side chain of a substrate and the second is as a `proton donor' to the oxyanion of the tetrahedral transition state to stabilize the reaction transition state. [source]

Crystallization of a 45,kDa peroxygenase/peroxidase from the mushroom Agrocybe aegerita and structure determination by SAD utilizing only the haem iron

Klaus Piontek
Some litter-decaying fungi secrete haem-thiolate peroxygenases that oxidize numerous organic compounds and therefore have a high potential for applications such as the detoxification of recalcitrant organic waste and chemical synthesis. Like P450 enzymes, they transfer oxygen functionalities to aromatic and aliphatic substrates. However, in contrast to this class of enzymes, they only require H2O2 for activity. Furthermore, they exhibit halogenation activity, as in the well characterized fungal chloroperoxidase, and display ether-cleavage activity. The major form of a highly glycosylated peroxygenase was produced from Agrocybe aegerita culture media, purified to apparent SDS homogeneity and crystallized under three different pH conditions. One crystal form containing two molecules per asymmetric unit was solved at 2.2, resolution by SAD using the anomalous signal of the haem iron. Subsequently, two other crystal forms with four molecules per asymmetric unit were determined at 2.3 and 2.6, resolution by molecular replacement. [source]

Four crystal forms of a Bence-Jones protein

Debora L. Makino
Four crystal forms have been grown and characterized by X-ray diffraction of a Bence-Jones protein collected from the urine of a multiple myeloma patient more than 40,years ago. Closely related tetragonal and orthorhombic forms belonging to space groups P43212 and P212121, with unit-cell parameters a = b = 68.7, c = 182.1 and a = 67.7, b = 69.4, c = 87.3,, diffract to 1.5 and 1.9,, respectively. Two closely related trigonal forms, both belonging to space group P3121 with unit-cell parameters a = b = 154.3, but differing by a doubling of the c axis, one 46.9, and the other 94.0,, diffract to 2.9 and 2.6, resolution, respectively. The trigonal crystal of short c -axis length shows a positive indication of twinning. The trigonal crystal of longer c axis, which appeared only after eight months of incubation at room temperature, is likely to be composed of proteolytically degraded molecules and unlike the other crystal forms contains two entire Bence-Jones dimers in the asymmetric unit. This latter crystal form may shed some light on the formation of fibrils common to certain storage diseases. [source]