Chemistry and biochemistry of some biologically active bacterial lipids.

Work, which was begun in the author's laboratory in 1948, on the chemistry of various lipid fractions of Mycobacteria and other acid-fast micro-organisms, has led to the identification and elucidation of the chemistry of a number of compounds having unusual structures and interesting biological activities. The principal compounds studied are branchedchain high molecular weight fatty acids, gl ycolipids and peptido-glycolipids. Some information on biosynthetic mechanisms in these series has also been obtained. The infection of a healthy animal or human being by tubercle bacilli gives rise to several pathological manifestations, such as: (i) formation of tubercles; (ii) establishment of a delayed type of hypersensitivity; (iii) loss of weight, haemorrhages, and death, due to the presence of a toxic factor; (iv) increased production of antibodies; (v) development of resistance to a second infection. We shall see that all of these pathological phenomena are due to particular lipid fractions of the tubercle bacillus. Besides these, we shall consider also a new category of glycolipids which are typical for certain strains of Mycobacteria (see Table 1).