PROTEIN-LIPID PARTICLES OF MEDICINAL LEECH SALIVARY GLAND SECRETION: THEIR SIZES AND MORPHOLOGY
First the picture of the positional relationship of proteins and lipids in particles consisting of medicinal leech salivary gland secretion (SGS) is reported. Their sizes and morphology are described. During investigations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), SGS bears resemblances to particles of different sizes and form. This picture is supported by confocal laser scanning microscopy of SGS preparations treated with FITC. After incubation with nonionic detergents (Brij 35 and Tween 20), TEM fixed the dissociation of fragments composed protein-lipid particles (P-LP). Increasing of free protein concentration was determined by a modified Lowry method. Probing of lipids in SGS preparations with perylene showed that they are concentrated mainly inside P-LP without touching the surface. Similarly, distributed cholesterol it detected by probing with bodipy-cholesteryl, a hydrophobic fluorescent analog of cholesterol. It is fixed on the surface of P-LP to a greater extent than lipids, which is seen on the surface sections during confocal analysis of electronic SGS pictures. This analysis detected in SGS P-LP the structures outwardly looking like caveoles full of cholesterol. SGS preliminarily frozen at -70°C transformed into a multitude of very small similar "particles" as seen by TEM visualization. Their fixed distribution resembles the crystalline structure of water.