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Extended Chains (extended + chain)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Fast and faster: A designed variant of the B-domain of protein A folds in 3 ,sec

PROTEIN SCIENCE, Issue 4 2004
Pooja Arora
Abstract We have introduced the mutation glycine 29 to alanine, designed to increase the rate of protein folding, into the B-domain of protein A (BdpA). From NMR lineshape analysis, we find the G29A mutation increases the folding rate constant by threefold; the folding time is 3 ,sec. Although wild-type BdpA folds extremely fast, simple-point mutations can still speed up the folding; thus, the folding rate is not evolutionarily maximized. The short folding time of G29A BdpA (the shortest time yet reported) makes it an attractive candidate for an all-atom molecular dynamics simulation that could potentially show a complete folding reaction starting from an extended chain. We also constructed a fluorescent variant of BdpA by mutating phenylalanine 13 to tryptophan, allowing fluorescence-based time-resolved temperature-jump measurements. Temperature jumps and NMR complement each other, and give a very complete picture of the folding kinetics. [source]

On the Lamellar Crystal Structure of Nylons 6,8 and 8,10: A Study Combining Electron Microscopy and Energy Analysis

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 1 2003
Marta Bermúdez
Abstract Lamellar crystals of nylon 6,8 and nylon 8,10 with chains in a fully extended conformation were obtained by crystallization in solution, and examined by electron and X-ray diffraction. The same crystal structure appeared to be shared by both nylons crystallized in glycerin. This structure consisted of a mixture of ,- and ,-forms with features similar to that previously described for lamellar crystals of nylon 4,6 grown in the same solvent. Crystallization of nylon 8,10 in hexane-2,5-diol afforded lamellar crystals with sheets stacked in the ,-form. A comparative energy evaluation of the different models that are feasible for the crystal structure of these nylons with fully extended chains indicated very small energy differences among them. The presence of different chain arrangements in the same lamellar crystal, as well as the crystallization of the same nylon in different crystal forms upon slight modification of the crystallization conditions, are fully consistent, therefore, with the results obtained in the energy analysis. Nylon 8,10 crystals grown in hexane-2,5-diol at 150,°C. Inset: The respective electron diffraction patterns. [source]

cis -Dichloridobis{dimethyl[3-(9-phosphabicyclo[3.3.1]non-9-yl)propyl]amine-,P}platinum(II)

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009
Peter N. Bungu
The title compound, [PtCl2(C13H26NP)2], is a rare example of a sterically bulky ligand adopting a cis geometry in a square-planar complex. It crystallizes on a twofold rotation axis which bisects the Pt centre and the P,Pt,P, and Cl,Pt,Cl, angles. The ligand exhibits a random packing disorder in the N,N -dimethylpropylamine substituent, with the two orientations refining to occupancies of 0.404,(15) and 0.596,(15). Weak intermolecular interactions between a Cl and a H atom of the ligand of a neighbouring molecule result in extended chains along the a axis. The effective cone angle for the dimethyl[3-(9-phosphabicyclo[3.3.1]non-9-yl)propyl]amine (Phoban[3.3.1]-C3NMe2) ligand was determined as being in the range 160,181°, depending on the choice of atoms used in the calculations. [source]

Bis­(pentane-1,5-di­ammonium) deca­iodo­triplumbate(II)

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2004
David G. Billing
The title compound, {(NH3C5H10NH3)2[Pb3I10]}n, crystallizes as an organic,inorganic hybrid. As such, the structure consists of extended chains of [Pb3I10]n4n, ions extending along [111]. The asymmetric unit contains two independent Pb atoms: one is in a general position and the other is on an inversion centre. Each Pb atom is octahedrally coordinated by six iodide ions and exhibits both face- and edge-sharing with adjacent atoms in the inorganic chain. The organic counter-ion, viz. pentane-1,5-di­ammonium, lies in channels formed by the chains and interacts with these chains via N,H,I hydrogen bonding. [source]