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Barua Bipasha Andersen Niels H. 《International journal of peptide research and therapeutics》2001,8(3-5):221-226
Summary A novel 20-residue fold, designated the ‘Trp-cage’ motif, has been shown to be 98+% folded in both water and 30 vol-% trifluoroethanol
solution. Folding is cooperative and hydrophobically driven, resulting in the burial of the Trp sidechain and a stable H-bond
from the Trp-εNH to a sequence remote backbone carbonyl. In the present study the effects of replacing the Trp with His, Phe
and both isomers of β-naphthylalanine are examined. The results suggest that the hydrophobic cluster is a specific interaction
of proline rings with the indole ring which can be partially mimicked by a naphthalene ring. The His and Phe mutants are completely
unfolded in aqueous medium. The naphthylalanine mutants form a stable hydrophobic cluster in 30% trifluoroethanol, but are
less stable in water than the native structure. 相似文献
216.
The cytohistopathologic features of a verrucous cervical carcinoma are reported. The presence in a cervical smear of two distinct types of dyskaryotic cells, with regularity of size and shape, and of occasional vacuolated cells set in a bright, eosinophilic background should suggest the lesion. With the cytologic suggestion and the typical warty clinical appearance of the tumor, an accurate preoperative diagnosis may be established. 相似文献
217.
We consider a pair of stochastic integrate and fire neurons receiving correlated stochastic inputs. The evolution of this system can be described by the corresponding Fokker?CPlanck equation with non-trivial boundary conditions resulting from the refractory period and firing threshold. We propose a finite volume method that is orders of magnitude faster than the Monte Carlo methods traditionally used to model such systems. The resulting numerical approximations are proved to be accurate, nonnegative and integrate to 1. We also approximate the transient evolution of the system using an Ornstein?CUhlenbeck process, and use the result to examine the properties of the joint output of cell pairs. The results suggests that the joint output of a cell pair is most sensitive to changes in input variance, and less sensitive to changes in input mean and correlation. 相似文献
218.
Retinoids are unstable compounds being readily oxidized and/or isomerized to altered compounds, especially in the presence
of oxidants including air, light, and excessive heat. They are labile toward strong acids and solvents that have dissolved
oxygen or peroxides. In this review, procedures for handling and storage of retinoids and biological samples containing them
have been described. The physical and chemical properties of retinoids have been reported. Simplified procedures for derivatizations
and purification, and methods for quantitation of retinoids have been presented. 相似文献
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