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151.
The folding and assembly of the Fv fragment of the phosphorylcholine binding antibody McPC603, a non-covalent heterodimer of the variable domains VH and VL, was investigated. Since both domains, each engineered for stability and folding efficiency, could now be obtained in native and soluble form by themselves, fluorescence spectra of VH and VL in unfolded, folded and associated states can be reported. VH and VL only associate when they are native, and the stability of the heterodimer is strongly increased in the presence of antigen. VH rapidly folds into an hyperfluorescent intermediate, and the native state is reached in two parallel, proline-independent reactions. VL displays two fast refolding reactions, which are followed by two slower phases, limited by proline cis/trans-isomerization. The rate-limiting step for both the Fv and the scFv (single-chain Fv) fragment is the formation of the native VH-VL interface, which depends on ProL95 being in cis. The folding of the Fv fragment is fast after short-term denaturation or in the presence of proline cis/trans-isomerase catalysis, but the scFv fragment falls into a kinetic trap, observed by the persistence of the slow phases under all conditions. Furthermore, the scFv fragment, but not the Fv fragment, gives rise to premature interface formation, indicated by the fluorescence spectra and a much higher transient binding of 8-anilino-1-naphthalene sulfonate. The analysis of the folding pathway of the domains VH and VL in isolation and in non-covalent and covalent assemblies should provide helpful insights into the folding of multimeric proteins in general, and for the further engineering of stable and well-folding antibody fragments in particular. 相似文献
152.
Moo-Young Huh Hyun-Chul Kim Jong-Jin Park Olaf Engler 《Metals and Materials International》1999,5(5):437-443
In order to investigate the evolution of through-thickness texture gradients in various ferritic steel sheets, samples of
a deep drawing steel, a ferritic stainless steel and a low carbon steel were deformed by cold rolling with and without application
of a lubricant during the deformation process. The hot band texture of all samples examined showed notable through-thickness
texture gradients. The evolution of the cold rolling texture in the ferritic stainless steel and the low carbon steel in a
solution-treated state was nearly independent of the lubrication during rolling. However, in the deep drawing steel and the
as-received low carbon steel, the lubrication played an important role in the formation of the through-thickness texture gradients.
Whereas the samples rolled with lubrication showed uniform textures throughout the sheet thickness, in the samples rolled
without lubrication pronounced shear textures were observed on the sheet surface. The evolution of these through-thickness
texture gradients is discussed in terms of inhomogeneous strain states computed by an FEM model.
This article is based on a presentation made in the symposium “ ’99 International Symposium on Textures of Materials”, held
at Sunchun National University, Sunchun, April 21–22, 1999 under the auspices of The Korean Institute of Metals and Materials
and The Research and Development Center for Automobile’s Parts and Materials. 相似文献
153.
154.
Degradation of cationic starches and subsequent permethylation and Hofmann-elimination of the methyl-glucosides yields the corresponding enolether derivatives, which can be analyzed by GLC and GLC-MS. The relative ratio of 2-, 3- and 6-substitution in the anhydroglucose unit as well as of un-, mono-, di- and trisubstitution in the anhydroglucose unit as well as of un-, mono-, di- and trisubstituted monomers can be determined. The experimental results are compared with the data calculated by means of a kinetic model. Only slight deviations from a random distribution in the anhydroglucose unit are observed and discussed. Enzymatic degradation of the cationic starch ethers and measurement of the liberated glucose should give indication to the distribution along the polymer chain. 相似文献
155.
Optical coatings:trends and challenges 总被引:1,自引:1,他引:0
1Introduction Today,opticalcoatinghasbeenregardedas oneofthemostimportantsegmentinoptics technology[1].Itcansufficientlyimprovethe performanceofthewholeopticalsystem,satisfy thefunctionrequirements,andthereforeisan intensivelyactiveresearchfieldworldwide.Opticalcoatingscanbefoundinnearly everytechnicalapplicationstartingwithtelecom munications,spacetechnologies,andlasers.Meanwhile,itplaysasignificantroleinmany fieldsdevelopment,suchasphysics,chemistry andsynchrotronemissionapplication.Theeffi… 相似文献
156.
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158.
In this paper we present a procedure for the selection of the minimal dc reverse bias voltage of a high-speed optically triggered sampling circuit. The optically triggered sampling circuit is based on a PIN photodiode. A set of expressions that includes the optical power dependence of the current passing through the PIN photodiode is derived. Theoretical results of the procedure are experimentally verified with practical measurements obtained from a 3 giga samples per second (GS/s) and a 20 GS/s sampling circuit implemented with commercial PIN photodiodes. Reductions in the signal-to-noise and distortion ratio of 37.28 and 6.9?dBs, as well as increments in the spurious free dynamic range of 31 and 19?dBs in the sampled signals, are respectively averted by the selection of the minimal reverse bias. 相似文献
159.
Copper island films have been prepared by thermal evaporation in vacuum and characterized by in situ as well as ex situ spectrophotometry. The parallel investigation of the island morphology by means of transmission electron microscopy allowed us to establish a clear correlation between film structure and optical properties. The effective optical constants of the copper island films could be determined by means of a fit of their ex situ transmission and reflection spectra. The effective optical constants have been used for designing and preparing optical multilayer coatings applicable for attenuator or color filter specifications. Measured characteristics of the multilayer coatings are in very good agreement with the calculated spectra. 相似文献
160.
Kye-Man Lee Hyung-Gu Kang Moo-Young Huh Olaf Engler 《Metals and Materials International》2010,16(5):851-856
Two different types of shear textures were observed in cold rolled aluminum sheets after normal rolling without lubrication
and after asymmetrical rolling carried out with the upper and lower rolls running at different velocities. Finite element
simulations showed that the formation of the different shear textures could be attributed to differences in the strain history
during rolling. The development of shear textures was quantified by assuming various idealized strain paths in polycrystal-plasticity
deformation texture simulations. The net shear accumulating during a rolling pass plays an important role in determining the
type of the resulting shear texture. 相似文献