Crystal structure of glyceraldehyde-3-phosphate dehydrogenase from Plasmodium falciparum at 2.25 Å resolution reveals intriguing extra electron density in the active site

2005 ◽  
Vol 62 (3) ◽  
pp. 570-577 ◽  
Author(s):  
Mark A. Robien ◽  
Jürgen Bosch ◽  
Frederick S. Buckner ◽  
Wesley C. E. Van Voorhis ◽  
Elizabeth A. Worthey ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Plasmodium Falciparum ◽  
Electron Density ◽  
Active Site ◽  
Extra Electron

Crystal structure of acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Kohei Sasamoto ◽  
Tomoki Himiyama ◽  
Kunihiko Moriyoshi ◽  
Takashi Ohmoto ◽  
Koichi Uegaki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cellulose Acetate ◽  
Electron Density ◽  
Active Site ◽  
Catalytic Domain ◽  
Crystal Packing ◽  
Signal Sequence ◽  
Industrial Applications ◽  
Side Chain ◽  
Active Site Conformation

The acetylxylan esterases (AXEs) classified into carbohydrate esterase family 4 (CE4) are metalloenzymes that catalyze the deacetylation of acetylated carbohydrates. AXE from Caldanaerobacter subterraneus subsp. tengcongensis (TTE0866), which belongs to CE4, is composed of three parts: a signal sequence (residues 1–22), an N-terminal region (NTR; residues 23–135) and a catalytic domain (residues 136–324). TTE0866 catalyzes the deacetylation of highly substituted cellulose acetate and is expected to be useful for industrial applications in the reuse of resources. In this study, the crystal structure of TTE0866 (residues 23–324) was successfully determined. The crystal diffracted to 1.9 Å resolution and belonged to space group I212121. The catalytic domain (residues 136–321) exhibited a (β/α)7-barrel topology. However, electron density was not observed for the NTR (residues 23–135). The crystal packing revealed the presence of an intermolecular space without observable electron density, indicating that the NTR occupies this space without a defined conformation or was truncated during the crystallization process. Although the active-site conformation of TTE0866 was found to be highly similar to those of other CE4 enzymes, the orientation of its Trp264 side chain near the active site was clearly distinct. The unique orientation of the Trp264 side chain formed a different-shaped cavity within TTE0866, which may contribute to its reactivity towards highly substituted cellulose acetate.

scholarly journals Crystal structure of Rv1220c, a SAM-dependentO-methyltransferase fromMycobacterium tuberculosis

2017 ◽  
Vol 73 (6) ◽  
pp. 315-320 ◽  
Author(s):  
Qiaoling Yan ◽  
Neil Shaw ◽  
Lanfang Qian ◽  
Dunquan Jiang
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Mycobacterium Tuberculosis ◽  
Electron Density ◽  
Active Site ◽  
Metal Binding ◽  
Structural Information

Rv1220c fromMycobacterium tuberculosisis annotated as anO-methyltransferase (MtbOMT). Currently, no structural information is available for this protein. Here, the crystal structure ofMtbOMT refined to 2.0 Å resolution is described. The structure reveals the presence of a methyltransferase fold and shows clear electron density for one molecule ofS-adenosylmethionine (SAM), which was apparently bound by the protein during its production inEscherichia coli. Although the overall structure ofMtbOMT resembles the structures ofO-methyltransferases fromCornybacterium glutamicum,Coxiella burnettiandAlfa alfa, differences are observed in the residues that make up the active site. Notably, substitution of Asp by His164 seems to abrogate metal binding byMtbOMT. A putative catalytic His–Asp pair located in the vicinity of SAM is absolutely conserved inMtbOMT homologues from all species ofMycobacterium, suggesting a conserved function for this protein.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

scholarly journals Crystal Structure, Exogenous Ligand Binding, and Redox Properties of an Engineered Diiron Active Site in a Bacterial Hemerythrin

2013 ◽  
Vol 52 (22) ◽  
pp. 13014-13020 ◽  
Author(s):  
Yasunori Okamoto ◽  
Akira Onoda ◽  
Hiroshi Sugimoto ◽  
Yu Takano ◽  
Shun Hirota ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ligand Binding ◽  
Active Site ◽  
Redox Properties ◽  
Exogenous Ligand

scholarly journals Crystal Structure of the Dithiol Oxidase DsbA Enzyme fromProteus MirabilisBound Non-covalently to an Active Site Peptide Ligand

2014 ◽  
Vol 289 (28) ◽  
pp. 19810-19822 ◽  
Author(s):  
Fabian Kurth ◽  
Wilko Duprez ◽  
Lakshmanane Premkumar ◽  
Mark A. Schembri ◽  
David P. Fairlie ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Peptide Ligand
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