No abstract

When a solution of collagen molecules, at neutral pH and moderate ionic strength, is warmed from 4 degrees to 30 degrees C, a spontaneous self-assembly process takes place in which native-type collagen fibers are produced. Events occurring during thermally induced fibrillogenesis process can be monitored, in aqueous media and in real time, by Fourier transform infrared spectroscopic techniques. Tentative assignments of observed spectral bands are given.

A spectroscopic technique has been developed and used in our laboratory to study the adsorption of proteins from flowing aqueous solutions in real time.I.2 This technique which couples Fourier transform infrared spectroscopy with attenuated total reflectance (ATR) optics allows protein adsorption kinetics and relative amounts of adsorbed protein to be determined in real time. Relative amounts of adsorbed protein can be determined because it has been established that the amide I1 (1550 cm-') and the 1400 cm-* infrared bands are linearly related to total amount of protein a d~o r b e d .~ After the adsorption study is completed, desorption studies are performed by circulating saline through the ATR cell. Desorption studies allow the determination of both the relative amounts of desorbed (loosely bound) protein and the relative amounts of residual, tightly bound protein.Protein adsorption, in situ, has been measured by attenuated total reflection fluorescence techniques.*5 In sifu measurements have not been made by ATR techniques except in this laboratory,lJ and these measurements are concentrated on spectral studies of composition rather then flow rates. This note reports in srtu ATR/FT-IR (Fourier transform infrared) measurements for albumin at different flow rates and at different concentrations. These relative quantitative values for adsorbed and desorbed albumin are then compared to values for fibrinogen and a 1 : 1 mixture of albumin and fibrinogen.

Pressure dependence of NMR proton spin-lattice relaxation times and shear viscosity in liquid water in the temperature range −15-10°C J. Chem. Phys. 66, 896 (1977); 10.1063/1.433995 Concentration dependent relaxation times in organic radical solidsProton spin-lattice relaxation times (T,) for hydrous melts of Ca(N0 3 )2 containing 2.8, 4.0, 8.0, and 16.0 moles H 2 0/mole salt (55.5 to 2.32 moles H 2 0/I) at temperatures between 290 and 390 K are analyzed in terms of intramolecular and intermolecular contributions. Rotational correlation times for water (T ro ,) are estimated from the relaxation rates in the high temperature (narrow line) region using intermolecular correlation times (Tin,.,) estimated from melt viscosities or from diffusivities of protons or of dilute solute ions (Cd2+). The ratio Tin'e/Tm, increases from about 2.5 in pure water to about 17 in the viscous melt Ca(N03)2-2.8 H 2 0, suggesting a much greater medium effect on translational than on rotational motion. An empirical relation was found that quantitatively correlates the dependence of the relaxation rate, varying over three orders of magnitude, with viscosity (or water diffusivity) and the volume concentration of water at all of the compositions and temperatures investigated.Following the treatment of Abragam, 13 the BPP ex-preSSion for the relaxation rate in the high temperature

Pulse and continuous wave NMR measurements are reported for protons in hydrous melts of calcium nitrate at temperatures between --4 ~ and 120~ At temperatures near 50~ mean Arrhenius coefficients, AHT1 (kcal/mole), are 7.9, 7.3, and 4.8, respectively, for melts containing 2.8, 4.0, and 8.0 moles of water per mole of calcium nitrate, compared to 4.6 kcal/mole for pure water. Temperature dependence of T1 and T2 in Ca(NOj)2-2.8 H20 between --4 ~ and 120~ are non-Arrhenius and can be represented by a Fulcher-type equation with a "zero mobility temperature" (T0) of 225~ close to the value of To for solute diffusion, electrical conductance, and viscosity. Resolution of the relaxation rates into correlation times for intramolecular (rotational) and intermolecular (translational) diffusional motion is discussed in terms of the Bloembergen-Purcell-Pound and more recent models for dipolar relaxation. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 35.8.11.2 Downloaded on 2015-06-14 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 35.8.11.2 Downloaded on 2015-06-14 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 35.8.11.2 Downloaded on 2015-06-14 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 35.8.11.2 Downloaded on 2015-06-14 to IP