scholarly journals Structure of a Clostridium botulinum C143S Thiaminase I/Thiamin Complex Reveals Active Site Architecture,

Biochemistry ◽  
2013 ◽  
Vol 52 (44) ◽  
pp. 7830-7839 ◽  
Author(s):  
Megan D. Sikowitz ◽  
Brateen Shome ◽  
Yang Zhang ◽  
Tadhg P. Begley ◽  
Steven E. Ealick
Keyword(s):  
Active Site ◽  
Clostridium Botulinum ◽  
Thiaminase I

scholarly journals Thiaminase I (42 kDa) heterogeneity, sequence refinement, and active site location from high-resolution tandem mass spectrometry

1995 ◽  
Vol 6 (10) ◽  
pp. 981-984 ◽  
Author(s):  
Neil L. Kelleher ◽  
Colleen A. Costello ◽  
Tadhg P. Begley ◽  
Fred W. McLafferty
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Tandem Mass Spectrometry ◽  
Active Site ◽  
Tandem Mass ◽  
Site Location ◽  
Thiaminase I

scholarly journals Structures of Clostridium botulinum Neurotoxin Serotype A Light Chain Complexed with Small-Molecule Inhibitors Highlight Active-Site Flexibility

2007 ◽  
Vol 14 (5) ◽  
pp. 533-542 ◽  
Author(s):  
Nicholas R. Silvaggi ◽  
Grant E. Boldt ◽  
Mark S. Hixon ◽  
Jack P. Kennedy ◽  
Saul Tzipori ◽  
...  
Keyword(s):  
Small Molecule ◽  
Light Chain ◽  
Active Site ◽  
Clostridium Botulinum ◽  
Botulinum Neurotoxin ◽  
Small Molecule Inhibitors ◽  
Serotype A ◽  
Botulinum Neurotoxin Serotype A

Cryo-electron microscopy of two-dimensional crystals of reduced type B botulinum neurotoxin

1992 ◽  
Vol 50 (1) ◽  
pp. 530-531
Author(s):  
P. F. Flicker ◽  
V.S. Kulkarni ◽  
J. P. Robinson ◽  
G. Stubbs ◽  
B. R. DasGupta
Keyword(s):  
Disulfide Bonds ◽  
Clostridium Botulinum ◽  
Structural Changes ◽  
Two Dimensional ◽  
Type B ◽  
Single Chain ◽  
Muscle Paralysis ◽  
Cryo Electron Microscopy ◽  
Disulfide Linkages ◽  
Intracellular Action

Botulinum toxin is a potent neurotoxin produced by Clostridium botulinum. The toxin inhibits release of neurotransmitter, causing muscle paralysis. There are several serotypes, A to G, all of molecular weight about 150,000. The protein exists as a single chain or or as two chains, with two disulfide linkages. In a recent investigation on intracellular action of neurotoxins it was reported that type B neurotoxin can inhibit the release of Ca++-activated [3H] norepinephrine only if the disulfide bonds are reduced. In order to investigate possible structural changes in the toxin upon reduction of the disulfide bonds, we have prepared two-dimensional crystals of reduced type B neurotoxin. These two-dimensional crystals will be compared with those of the native (unreduced) type B toxin.

Locating Al in the DABCO catalyst before and after Al extraction

1990 ◽  
Vol 48 (4) ◽  
pp. 265-267
Author(s):  
Kathleen B. Reuter
Keyword(s):  
Active Site ◽  
Inverse Relationship ◽  
Transverse Direction ◽  
Reaction Rate ◽  
Acid Phosphate ◽  
Fracture Surfaces ◽  
Al Content ◽  
Before And After ◽  
Relationship Of

The reaction rate and efficiency of piperazine to 1,4-diazabicyclo-octane (DABCO) depends on the Si/Al ratio of the MFI topology catalysts. The Al was shown to be the active site, however, in the Si/Al range of 30-200 the reaction rate increases as the Si/Al ratio increases. The objective of this work was to determine the location and concentration of Al to explain this inverse relationship of Al content with reaction rate.Two silicalite catalysts in the form of 1/16 inch SiO2/Al2O3 bonded extrudates were examined: catalyst A with a Si/Al of 83; and catalyst B, the acid/phosphate Al extracted form of catalyst A, with a Si/Al of 175. Five extrudates from each catalyst were fractured in the transverse direction and particles were obtained from the fracture surfaces near the center of the extrudate diameter. Particles were also obtained from the outside surfaces of five extrudates.

Structures of c-di-GMP/cGAMP degrading phosphodiesterase VcEAL: identification of a novel conformational switch and its implication

2019 ◽  
Vol 476 (21) ◽  
pp. 3333-3353 ◽  
Author(s):  
Malti Yadav ◽  
Kamalendu Pal ◽  
Udayaditya Sen
Keyword(s):  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Triosephosphate Isomerase ◽  
Catalytic Mechanism ◽  
Degradation Mechanism ◽  
Structural Basis ◽  
Conserved Residues ◽  
Phosphodiester Bond ◽  
Cyclic Dinucleotides

Cyclic dinucleotides (CDNs) have emerged as the central molecules that aid bacteria to adapt and thrive in changing environmental conditions. Therefore, tight regulation of intracellular CDN concentration by counteracting the action of dinucleotide cyclases and phosphodiesterases (PDEs) is critical. Here, we demonstrate that a putative stand-alone EAL domain PDE from Vibrio cholerae (VcEAL) is capable to degrade both the second messenger c-di-GMP and hybrid 3′3′-cyclic GMP–AMP (cGAMP). To unveil their degradation mechanism, we have determined high-resolution crystal structures of VcEAL with Ca2+, c-di-GMP-Ca2+, 5′-pGpG-Ca2+ and cGAMP-Ca2+, the latter provides the first structural basis of cGAMP hydrolysis. Structural studies reveal a typical triosephosphate isomerase barrel-fold with substrate c-di-GMP/cGAMP bound in an extended conformation. Highly conserved residues specifically bind the guanine base of c-di-GMP/cGAMP in the G2 site while the semi-conserved nature of residues at the G1 site could act as a specificity determinant. Two metal ions, co-ordinated with six stubbornly conserved residues and two non-bridging scissile phosphate oxygens of c-di-GMP/cGAMP, activate a water molecule for an in-line attack on the phosphodiester bond, supporting two-metal ion-based catalytic mechanism. PDE activity and biofilm assays of several prudently designed mutants collectively demonstrate that VcEAL active site is charge and size optimized. Intriguingly, in VcEAL-5′-pGpG-Ca2+ structure, β5–α5 loop adopts a novel conformation that along with conserved E131 creates a new metal-binding site. This novel conformation along with several subtle changes in the active site designate VcEAL-5′-pGpG-Ca2+ structure quite different from other 5′-pGpG bound structures reported earlier.

Contributions of the substrate-binding arginine residues to maleate-induced closure of the active site of Escherichia coli aspartate aminotransferase

2001 ◽  
Vol 268 (6) ◽  
pp. 1640-1645
Author(s):  
Annelise Matharu ◽  
Hideyuki Hayashi ◽  
Hiroyuki Kagamiyama ◽  
Bruno Maras ◽  
Robert A. John
Keyword(s):  
Escherichia Coli ◽  
Active Site ◽  
Aspartate Aminotransferase ◽  
Substrate Binding ◽  
Arginine Residues

Alkane upgrading effected by silica-supported pincer-iridium catalysts: Evidence of a shared active site with solution-phase species

2020 ◽  
Author(s):  
Alan Goldman ◽  
Boris Sheludko ◽  
Fuat Celik ◽  
Cristina Castro
Keyword(s):  
Active Site ◽  
Solution Phase ◽  
Iridium Catalysts

Active site-inhibited seven: Mechanism of action including signal transduction

2001 ◽  
Vol 38 (4F) ◽  
pp. 39-42 ◽  
Author(s):  
Lars C. Petersen
Keyword(s):  
Signal Transduction ◽  
Mechanism Of Action ◽  
Active Site

Ancylostoma caninum Anticoagulant Peptide Blocks Metastasis In Vivo and Inhibits Factor Xa Binding to Melanoma Cells In Vitro

1998 ◽  
Vol 79 (05) ◽  
pp. 1041-1047 ◽  
Author(s):  
Kathleen M. Donnelly ◽  
Michael E. Bromberg ◽  
Aaron Milstone ◽  
Jennifer Madison McNiff ◽  
Gordon Terwilliger ◽  
...  
Keyword(s):  
Active Site ◽  
Thrombin Generation ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Melanoma Cells ◽  
Factor V ◽  
Ancylostoma Caninum ◽  
Metastatic Activity

SummaryWe evaluated the in vivo anti-metastatic activity of recombinant Ancylostoma caninum Anticoagulant Peptide (rAcAP), a potent (Ki = 265 pM) and specific active site inhibitor of human coagulation factor Xa originally isolated from bloodfeeding hookworms. Subcutaneous injection of SCID mice with rAcAP (0.01-0.2 mg/mouse) prior to tail vein injection of LOX human melanoma cells resulted in a dose dependent reduction in pulmonary metastases. In order to elucidate potential mechanisms of rAcAP’s anti-metastatic activity, experiments were carried out to identify specific interactions between factor Xa and LOX. Binding of biotinylated factor Xa to LOX monolayers was both specific and saturable (Kd = 15 nM). Competition experiments using antibodies to previously identified factor Xa binding proteins, including factor V/Va, effector cell protease receptor-1, and tissue factor pathway inhibitor failed to implicate any of these molecules as significant binding sites for Factor Xa. Functional prothrombinase activity was also supported by LOX, with a half maximal rate of thrombin generation detected at a factor Xa concentration of 2.4 nM. Additional competition experiments using an excess of either rAcAP or active site blocked factor Xa (EGR-Xa) revealed that most of the total factor Xa binding to LOX is mediated via interaction with the enzyme’s active site, predicting that the vast majority of cell-associated factor Xa does not participate directly in thrombin generation. In addition to establishing two distinct mechanisms of factor Xa binding to melanoma, these data raise the possibility that rAcAP’s antimetastatic effect in vivo might involve novel non-coagulant pathways, perhaps via inhibition of active-site mediated interactions between factor Xa and tumor cells.

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