Role of C-terminal methylation and side chain guanidinium group of arginine in stabilization of gold nanoparticles

2019 ◽  
Author(s):  
Manish Bajaj ◽  
Rohit K. Sharma
Keyword(s):  
Gold Nanoparticles ◽  
Side Chain ◽  
Guanidinium Group

scholarly journals “Newton’s cradle” proton relay with amide–imidic acid tautomerization in inverting cellulase visualized by neutron crystallography

2015 ◽  
Vol 1 (7) ◽  
pp. e1500263 ◽  
Author(s):  
Akihiko Nakamura ◽  
Takuya Ishida ◽  
Katsuhiro Kusaka ◽  
Taro Yamada ◽  
Shinya Fushinobu ◽  
...  
Keyword(s):  
Glycoside Hydrolases ◽  
Side Chain ◽  
Enzymatic Reactions ◽  
X Ray Diffraction ◽  
Peptide Bonds ◽  
Proton Relay ◽  
Newton’S Cradle ◽  
Dynamics Simulations ◽  
Hydrolysis Of

Hydrolysis of carbohydrates is a major bioreaction in nature, catalyzed by glycoside hydrolases (GHs). We used neutron diffraction and high-resolution x-ray diffraction analyses to investigate the hydrogen bond network in inverting cellulase PcCel45A, which is an endoglucanase belonging to subfamily C of GH family 45, isolated from the basidiomycete Phanerochaete chrysosporium. Examination of the enzyme and enzyme-ligand structures indicates a key role of multiple tautomerizations of asparagine residues and peptide bonds, which are finally connected to the other catalytic residue via typical side-chain hydrogen bonds, in forming the “Newton’s cradle”–like proton relay pathway of the catalytic cycle. Amide–imidic acid tautomerization of asparagine has not been taken into account in recent molecular dynamics simulations of not only cellulases but also general enzyme catalysis, and it may be necessary to reconsider our interpretation of many enzymatic reactions.

scholarly journals The Role of Arg13 in Protein Phosphatase M tPphA from Thermosynechococcus elongatus

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jiyong Su ◽  
Karl Forchhammer
Keyword(s):  
Amino Acid ◽  
Protein Phosphatase ◽  
Arginine Residue ◽  
Side Chain ◽  
Wild Type ◽  
Catalytic Center ◽  
Nitrophenyl Phosphate ◽  
Reduced Activity ◽  
Amino Acid Variants

A highly conserved arginine residue is close to the catalytic center of PPM/PP2C-type protein phosphatases. Different crystal structures of PPM/PP2C homologues revealed that the guanidinium side chain of this arginine residue can adopt variable conformations and may bind ligands, suggesting an important role of this residue during catalysis. In this paper, we randomly mutated Arginine 13 of tPphA, a PPM/PP2C-type phosphatase from Thermosynechococcus elongatus, and obtained 18 different amino acid variants. The generated variants were tested towards p-nitrophenyl phosphate and various phosphopeptides. Towards p-nitrophenyl phosphate as substrate, twelve variants showed 3–7 times higher Km values than wild-type tPphA and four variants (R13D, R13F, R13L, and R13W) completely lost activity. Strikingly, these variants were still able to dephosphorylate phosphopeptides, although with strongly reduced activity. The specific inability of some Arg-13 variants to hydrolyze p-nitrophenyl phosphate highlights the importance of additional substrate interactions apart from the substrate phosphate for catalysis. The properties of the R13 variants indicate that this residue assists in substrate binding.

The Role of Silver and Gold Nanoparticles in Enhancing Luminescence of Europium Complexes

2014 ◽  
Vol 14 (6) ◽  
pp. 4357-4362 ◽  
Author(s):  
Hongyan Zhao ◽  
Feng Song ◽  
Fengxiao Wang ◽  
Jiadong Liu ◽  
Yanling Liu ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Europium Complexes ◽  
Silver And Gold Nanoparticles

Accessibility in Calix[8]arene-Bound Gold Nanoparticles: Crucial Role of Induced-Fit Binding

2010 ◽  
Vol 114 (38) ◽  
pp. 16060-16070 ◽  
Author(s):  
Jeong-Myeong Ha ◽  
Andrew Solovyov ◽  
Alexander Katz
Keyword(s):  
Gold Nanoparticles ◽  
Crucial Role ◽  
Induced Fit

Role of Hydroxyl Groups in Low-Temperature CO Catalytic Oxidation over Zn4Si2O7(OH)2 Nanowire-Supported Gold Nanoparticles

2018 ◽  
Vol 122 (44) ◽  
pp. 25456-25466 ◽  
Author(s):  
Jing-Jing Li ◽  
Bao-Lin Zhu ◽  
Gui-Chang Wang ◽  
Zun-Feng Liu ◽  
Wei-Ping Huang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Low Temperature ◽  
Catalytic Oxidation ◽  
Hydroxyl Groups ◽  
Co Catalytic Oxidation ◽  
Supported Gold Nanoparticles ◽  
Supported Gold
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