Description by quasi elastic laser light scattering of a biological preparation: sarcoplasmic reticulum vesicles.

Abstract

Quasi elastic laser light scattering (QELS) was used to describe the size and the homogeneity of a membrane preparation: vesicles from skeletal sarcoplasmic reticulum. The data were compared with results obtained by electron-microscopy. The advantages of each method are discussed. By electron-microscopy the average value for the diameter of the vesicles obtained after negative staining is 0.100±0.040 μm. With the freeze-etching technique this value ranges from 0.13 to 0.25 μm. For the same biological preparation the analysis of the QELS recording curves displaying one correlation time (τ) gives an apparent diameter for the vesicles of 0.17 μm. Although it is difficult to describe by QELS the homogeneity of the preparation, the technique remains a very convenient method for evaluating variation of the size of the vesicles, and thus offers the possibility to follow general modification in the size of a vesicular preparation. The effect of trypsin and phospholipase C treatment on vesicle size is studied: an increase of vesicle size is clearly observed after trypsin treatment.