Home  About us  Contact
 

Equivalent Site (equivalent + site)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Novel brain 14-3-3 interacting proteins involved in neurodegenerative disease

FEBS JOURNAL, Issue 16 2005
Shaun Mackie
We isolated two novel 14-3-3 binding proteins using 14-3-3 , as bait in a yeast two-hybrid screen of a human brain cDNA library. One of these encoded the C-terminus of a neural specific armadillo-repeat protein, ,-catenin (neural plakophilin-related arm-repeat protein or neurojungin). ,-Catenin from brain lysates was retained on a 14-3-3 affinity column. Mutation of serine 1072 in the human protein and serine 1094 in the equivalent site in the mouse homologue (in a consensus binding motif for 14-3-3) abolished 14-3-3 binding to ,-catenin in vitro and in transfected cells. ,-catenin binds to presenilin-1, encoded by the gene most commonly mutated in familial Alzheimer's disease. The other clone was identified as the insulin receptor tyrosine kinase substrate protein of 53 kDa (IRSp53). Human IRSp53 interacts with the gene product implicated in dentatorubral-pallidoluysian atrophy, an autosomal recessive disorder associated with glutamine repeat expansion of atrophin-1. [source]

Trigonal sodium cal­cium germanate, Na2.54Ca1.73Ge3O9

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2001
Fumito Nishi
Single crystals of a new germanate, Na2.54Ca1.73Ge3O9, have been synthesized. The structure has a six-membered ring of GeO4 tetrahedra, which is similar to the rings of the silicate analogue Na2Ca2Si3O9, and both structures contain pseudo-cubic subcells with an edge length of 3.8,Å. The details of the two compounds are slightly different, however. For example, two O atoms are statistically distributed about twofold axes in the title compound, while the silicate analogue has no such O-atom distributions. In addition, the title germanate has an extra partially populated metal site containing 54,(4)% Na, with no equivalent site in the silicate analogue. [source]

Structure of the M148Q mutant of rusticyanin at 1.5,Å: a model for the copper site of stellacyanin

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2001
Michael A. Hough
The small blue copper protein rusticyanin from Thiobacillus ferrooxidans contains a type 1 Cu centre with a single axial ligand, Met148, which together with the His-Cys-His trigonal planar ligands produces a distorted trigonal pyramidal coordination geometry to copper. Type 1 Cu sites are found in cupredoxins and several multicopper proteins, including oxidases and nitrite reductases. The role of the axial ligand has been extensively debated in terms of its function in the fine tuning of the redox potential and spectroscopic properties of type 1 Cu sites. Numerous mutations of the Met ligand in azurins have been studied, but interpretation of the results has been complicated by the presence of the additional carbonyl oxygen ligand from Gly45, a neighbouring residue to the coordinating His46. The importance of the axial ligand has been further emphasized by the finding that the type 1 centre in Rhus vernicifera stellacyanin, with the lowest redox potential in a type 1 Cu site of 184,mV, has Gln as the axial ligand, whilst fungal laccase and ceruloplasmin, which have redox potentials of 550,800,mV, have a Leu in this position. Here, the crystal structure of the M148Q mutant of rusticyanin at 1.5,Å resolution is presented. This is a significantly higher resolution than that of the structures of native rusticyanin. In addition, the M148Q structure is that of the oxidized protein while the native structures to date are of the reduced protein. The mutant protein crystallizes with two molecules per asymmetric unit, in contrast to the one present in the native crystal form. This mutant's redox potential (550,mV at pH 3.2) is lowered compared with that of the native protein (,670,mV at pH 3.2) by about 120,mV. The type 1 Cu site of M148Q closely mimics the structural characteristics of the equivalent site in non-glycosylated cucumber stellacyanin (redox potential ,260,mV) and, owing to the absence in rusticyanin of the fifth, carbonyl ligand present in azurin, may provide a better model for the R. vernicifera stellacyanin (redox potential ,184,mV) type 1 Cu site, which also lacks the fifth ligand. Furthermore, the presence of two molecules in the asymmetric unit cell indicates a potential binding region of the redox partners. [source]

Crystal structures and isotope effect on Na5H3(SeO4)4·2H2O and Na5D3(SeO4)4·2D2O crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2010
T. Fukami
Abstract Differential scanning calorimetry (DSC) and X-ray diffraction measurements have been performed on pentasodium trihydrogen tetraselenate dihydrate Na5H3(SeO4)4·2H2O and deuterated Na5D3(SeO4)4·2D2O crystals. Any distinct anomaly around 428 K in the DSC curves for both crystals is suggested to be caused by a chemical reaction of thermal decomposition with hydrolysis at high temperature. The space group symmetry (triclinic P) and the structure parameters are determined at room temperature. The hydrogen atom in the centrosymmetric O-H(D)-O hydrogen bond of both crystals is found to be equally distributed at two equivalent sites in the bond. The expansions of two O-H-O hydrogen bonds by the substitution of deuterium are observed to be 0.016(6) and 0.011(4) Å. The geometric isotope effect on hydrogen bonds is confirmed to be existed in Na5H3(SeO4)4·2H2O. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]