Quasi-elastic light scattering from structured particles

We present a formulation by which the scattered field correlation function of a nonstationary structured particle can be calculated. Specifically, we consider the case of micron-size bacteria, where the Rayleigh- Gans-Debye approximation may be used to evaluate the correlation function. We show that the width of the intensity correlation spectrum (as measured, for example, by the photon correlation technique) exhibits I an oscillatory behavior which is characteristic of the interference pattern produced by the internal structure. Two cases are of interest: diffusion and motility are considered in detail, and some evidence of the predicted behavior is shown from the photon correlation measurement of E. coli bacteria.

Raman studies of the conformation of the basic pancreatic trypsin inhibitor

The vibrational Raman spectra of the basic pancreatic trypsin inhibitor in aqueous solution, as lyophilized powder and in a single crystal and presented. The thermal stability of this protein is demonstrated by the fact that minor alterations in the spectrum, mainly in the amide III band near 1260 cm-1, occur in the solution spectrum only at temperatures above 75 degrees C. No significant spectral changes appear when the pH value of the solution is varied in the range from 1.5 to 8.7. The distinct differences of the powder spectrum compared to that of the solution, show that lyophilization causes appreciable conformational changes both in the main-chain and in the side-chains. A difference in main chain conformation of the basic pancreatic trypsin inhibitor in single crystal and in solution is suggested by different amide III frequencies.