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181.
182.
Golemi-Kotra D Mahaffy R Footer MJ Holtzman JH Pollard TD Theriot JA Schepartz A 《Journal of the American Chemical Society》2004,126(1):4-5
Many protein domains involved in cell signaling contain or interact with proline-rich sequences, and the design of molecules that perturb signaling pathways represents a foremost goal of chemical biology. Previously we described a protein design strategy in which the well-folded alpha-helix in avian pancreatic polypeptide (aPP) presents short alpha-helical recognition epitopes. The miniature proteins designed in this way recognize even shallow protein clefts with high affinity and specificity. Here we show that the well-folded type-II polyproline helix in aPP can present the short PPII-helical recognition epitope within the ActA protein of Listeria monocytogenes. Like miniature proteins that use an alpha-helix for protein recognition, the miniature protein designed in this way displays high affinity for a natural ActA target, the EVH1 domain Mena1-112, and achieves the elusive goal of paralog specificity, discriminating well between EVH1 domains Mena1-112, VASP1-115, and Evl1-112. Most importantly, the miniature protein competed with ActA in Xenopus laevis egg cytoplasmic extracts, decreasing actin-dependent motility of L. monocytogenes and causing extreme speed variations and discontinuous tail formation. Our results suggest that miniature proteins based on aPP may represent an excellent framework for the design of ligands that differentiate the roles of EVH1 domains in vitro and in vivo. 相似文献
183.
K. Haneda X. Z. Zhou A. H. Morrish R. J. Pollard T. Majima 《Hyperfine Interactions》1990,54(1-4):551-556
Ultrafine antiferromagnetic FeF2 particles (<10 nm) were prepared by a new technique, viz, the SF6-sensitized infrared photodecomposition of Fe(CO)5 induced by a transversely excited atmospheric (TEA) CO2 laser. The magnetic properties have been examined by57Fe Mössbauer spectroscopy. At low temperatures the magnetic hyperfine field decreases faster with increasing temperature than the hyperfine field of the bulk; this behavior appears to be consistent with collective magnetic excitations. The transition between the paramagnetic and antiferromagnetic states takes place at a higher temperature and over a broader range as compared to the bulk. FeF2 ultrafine particles are relatively sensitive to oxidation; cubic-type iron oxide is formed. 相似文献
184.
A stable vector algorithm for the solution of block diagonallinear systems is obtained by a permutation of the unknownscalled wrap-around partitioning combined with standard QR factorization.Wrap-around partitioning uses blocking and selects the unknownsin the blocks in turns. After a suitable orthogonal eliminationstep one ends up with a reduced system which is again blockbidiagonal and so wrap-around partitioning can be applied again.Using a simple model for vectorization overhead it is shownthat small block sizes give best performance. The minimal blocksize 2, which corresponds to cyclic reduction, is suboptimaldue to memory bank conflicts. 相似文献
185.
186.
Two hundred ninety experimental absolute intensities of nu(1) and nu(3) transitions of ozone have been measured, with good accuracy (<2%). They are used to derive the transition-moment parameters for these bands. The agreement between our observed and calculated line intensities is satisfactory. This work shows that the intensities of these two bands are on average 4% smaller than those used in the literature. In addition, 20 intensities of the nu(2) + nu(3) - nu(2) band confirm this value. Also, 42 line intensities of the 2nu(1)-nu(3) band are reported. Copyright 2001 Academic Press. 相似文献
187.
188.
Matthew J. Pollard Christopher K. Hilton Hongli Li Kimberly Kaplan Richard A. Yost Herbert H. HillJr. 《International Journal for Ion Mobility Spectrometry》2011,14(1):15-22
Since the development of electrospray ionization (ESI) for ion mobility spectrometry mass spectrometry (IMMS), IMMS have been
extensively applied for characterization of gas-phase bio-molecules. Conventional ion mobility spectrometry (IMS), defined
as drift tube IMS (DT-IMS), is typically a stacked ring design that utilizes a low electric field gradient. Field asymmetric
ion mobility spectrometry (FAIMS) is a newer version of IMS, however, the geometry of the system is significantly different
than DT-IMS and data are collected using a much higher electric field. Here we report construction of a novel ambient pressure
dual gate DT-IMS coupled with a FAIMS system and then coupled to a quadrupole ion trap mass spectrometer (QITMS) to form a
hybrid three-dimensional separation instrument, DT-IMS-FAIMS-QITMS. The DT-IMS was operated at ~3 Townsend (electric field/number
density (E/N) or (Td)) and was coupled in series with a FAIMS, operated at ~80 Td. Ions were mobility-selected by the dual
gate DT-IMS into the FAIMS and from the FAIMS the ions were detected by the QITMS for as either MS or MSn. The system was evaluated using cocaine as an analytical standard and tested for the application of separating three isomeric
tri-peptides: tyrosine-glycine-tryptophan (YGW), tryptophan-glycine-tyrosine (WGY) and tyrosine-tryptophan-glycine (YWG).
All three tri-peptides were separated in the DT-IMS dimension and each had one mobility peak. The samples were partially separated
in the FAIMS dimension but two conformation peaks were detected for the YWG sample while YGW and WGY produced only one peak.
Ion validation was achieved for all three samples using QITMS. 相似文献
189.
Ernesto A Aguilar Salegio Anthony N Pollard Malcolm Smith Xin-Fu Zhou 《BMC neuroscience》2011,12(1):11
Background
Injury to the peripheral branch of dorsal root ganglia (DRG) neurons prior to injury to the central nervous system (CNS) DRG branch results in the regeneration of the central branch. The exact mechanism mediating this regenerative trigger is not fully understood. It has been proposed that following peripheral injury, the intraganglionic inflammatory response by macrophage cells plays an important role in the pre-conditioning of injured CNS neurons to regenerate. In this study, we investigated whether the presence of macrophage cells is crucial for this type of regeneration to occur. We used a clodronate liposome technique to selectively and temporarily deplete these cells during the conditioning phase of DRG neurons. 相似文献190.
S. Sankar MR. Manikandan S.D. Gopal Ram T. Mahalingam G. Ravi 《Journal of Crystal Growth》2010,312(19):2729-2733
The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. 相似文献