Bactericidal activity of rat leucocytic extracts. II. Characterization of the bactericidal substance in leucocyte mitochondrial extracts.

The bactericidal substance present in mitochondrial extracts from rat leucocytes was found to be non-dialyzable, fractionated at 30 per cent (NH(4)SO(4) saturation and was able to withstand temperatures up to 100 degrees C. The tentative identification of a lipoprotein as the responsible bactericidal substance is based on various observations; an ultraviolet absorption at a peak associated with alpha, beta unsaturated fatty acids, 205 to 208 mmicro, inactivation of the bactericidal substance by ether treatment at -70 degrees C. but not at 0 degrees C. and inhibition of the bactericidal activity with lipase treatment as well as with trypsin.