The ratio of hapten and bovine serum albumin in an antigen conjugate was determined by matrix-assisted laser desorption/ionization mass spectrometry. A hybridoma secreting monoclonal antibodies against solamargine was produced by fusing splenocytes immunized with a solamargine-bovine serum albumin conjugate with HAT-sensitive mouse myeloma cell line, P3-X63-Ag8-653. Extensive cross-reaction of anti-solamargine antibodies against solasonine appeared. Aglycone of solamargine, solasodine cross-reacted with anti-solamargine antibodies resulting in a 43.8% cross-reaction. Insignificant cross-reaction appeared with tomatine (2.06%). The full measuring range of the assay extends from 57.5 pmol ml(-1) to 11.5 nmol ml(-1) of solamargine.

No abstract

CooA from Rhodospirillum rubrum is a transcriptional activator in which a heme prosthetic group acts as a CO sensor and regulates the activity of the protein.In this study, the electronic relaxation of the heme, and the concurrent recombination between ligands and the heme at ϳ280 K were examined in an effort to understand the environment around the heme and the dynamics of the ligands. Upon photoexcitation of the reduced CooA at 400 nm, electronic relaxation of the heme occurred with time constants of 0.8 and 1.7 ps. The ligand rebinding was substantially completed with a time constant of 6.5 ps, followed by a slow relaxation process with a time constant of 173 ps. In the case of CO-bound CooA, relaxation of the excited heme occurred with two time constants, 1.1 and 2.4 ps, which were largely similar to those with reduced CooA. The subsequent CO recombination process was remarkably fast compared with that of other CO-bound heme proteins. It was well described as a biphasic geminate recombination process with time constants of 78 ps (60%) and 386 ps (30%). About 10% of the excited heme remained unligated at 1.9 ns. The dynamics of rebinding of CO thus will help us to understand how the physiologically relevant diatomic molecule approaches the heme binding site in CooA with picosecond resolution.CooA, a transcriptional activator from Rhodospirillum rubrum, is a heme protein that acts as a CO sensor in vivo by binding . CooA is the first example of a transcriptional regulator containing heme as a prosthetic group (1). Only CObound CooA activates transcription of the genes for the key CO-oxidizing enzymes (2-6). Although the ferrous heme in CooA is in a six-coordinate form (3, 4), one of the heme axial ligands is replaced by exogenous CO upon the binding of CO (3,5,7), which triggers the conformational change in CooA required for specific binding to the target DNA (2,3,5,6,8).Though CO has been widely used as a probe to study the biochemical and biophysical properties of heme proteins, it has been thought to have no physiological role. CooA is the first example of a heme protein in which CO has a physiological function. Analysis of the dynamics of binding and escape of the ligand in heme proteins provides information on the intrinsic reactivity of the site for heme iron biding with the ligand, and how the reactivity and the pathway of the ligand are controlled by the protein. Observation of the motion of ligands such as O 2 , NO, and CO within heme proteins is facilitated by the simple photodissociation of diatom-heme protein complexes (9 -11). The dynamics of geminate rebinding, escaping, and bimolecular rebinding of ligands can be studied by various spectroscopic methods over a wide time range.Flash photolysis studies on CO-bound CooA will provide some useful information on the mechanisms of CO sensing by the heme and information on the regulation of CooA activity by CO. Measurement of transient absorption in the Soret band region on a tens of nanosecond or longer time scale has recently been carried out in studi...

Resonant Ultrasound Spectroscopy has been used to characterize elastic and anelastic anomalies in a polycrystalline sample of multiferroic Pb(Fe(0.5)Nb(0.5))O(3) (PFN). Elastic softening begins at ~550 K, which is close to the Burns temperature marking the development of dynamical polar nanoregions. A small increase in acoustic loss at ~425 K coincides with the value of T(*) reported for polar nanoregions starting to acquire a static or quasi-static component. Softening of the shear modulus by ~30-35% through ~395-320 K, together with a peak in acoustic loss, is due to classical strain/order parameter coupling through the cubic → tetragonal → monoclinic transition sequence of ferroelectric/ferroelastic transitions. A plateau of high acoustic loss below ~320 K is due to the mobility under stress of a ferroelastic microstructure but, instead of the typical effects of freezing of twin wall motion at some low temperature, there is a steady decrease in loss and increase in elastic stiffness below ~85 K. This is attributed to freezing of a succession of strain-coupled defects with a range of relaxation times and is consistent with a report in the literature that PFN develops a tweed microstructure over a wide temperature interval. No overt anomaly was observed near the expected Néel point, ~145 K, consistent with weak/absent spin/lattice coupling but heat capacity measurements showed that the antiferromagnetic transition is actually smeared out or suppressed. Instead, the sample is weakly ferromagnetic up to ~560 K, though it has not been possible to exclude definitively the possibility that this could be due to some magnetic impurity. Overall, evidence from the RUS data is of a permeating influence of static and dynamic strain relaxation effects which are attributed to local strain heterogeneity on a mesoscopic length scale. These, in turn, must have a role in determining the magnetic properties and multiferroic character of PFN.

Low-temperature direct bonding of poly-methylmethacrylate (PMMA) plates was achieved by pre-treatment with vacuum ultraviolet irradiation in the presence of oxygen gas (VUV/O3), with vacuum ultraviolet irradiation in a nitrogen atmosphere (VUV), or with oxygen plasma. Based on surface analysis by attenuated total reflection Fourier-transform infrared spectrometry (ATR-FT-IR), x-ray photoelectron spectroscopy and near edge x-ray absorption fine structure spectroscopy, chemical changes of the PMMA surface after the pre-treatment were investigated. Changes in morphology and softening point were also investigated by nano-thermal analysis and atomic force microscopy. From the results, the bonding mechanisms proposed are described as follows: during the bonding process, the increased or generated polar groups cause an increase in the dipolar interactions (such as hydrogen bonding) between two pre-treated PMMA surfaces; in the case of VUV/O3 or VUV pre-treatment, a low-Tg layer is generated on the surface and this layer acts as an adhesive for the direct bonding of layers by diffusion.