Muramic acid 8-lactam

Under certain circumstances, many bacteria produce capsules outside their ceU envelopes. Capsules are usually made of polysaccharide however, some Bacillus capsules are composed of D-glutamic acid polypeptide. Certain Gram positive bacteria, most notably strains of Bacillus and Clostridium, produce modified ceUs (endospores) capable of surviving in adverse environments. Spore PG is found between an inner and outer membrane and differs from that in the normal vegetative cell muramic acid is mostly in the lactam form the spore PG has fewer peptide cross-links and the ceU exterior is coated with keratin. The spore also contains large quantities of calcium dipicolinate, a substance involved in microbial heat resistance. 

The substitution of sodium acetate or N-methyl-imldazole for pyridine in the preparation of alditol acetate derivatives for the capillary g.c. analysis of neutral and amino-sugars using selected ion monitoring m.s. detection has been examined. While N-methyl-imidazole effected full acetylation of alditols in the presence of borates and water, it led to a higher detector background than the more tedious use of sodium acetate. Muramic acid produced two alditol acetate derivatives, the lactams (1) and (2), in a reproduceable fashion only in the sodium acetate-catalyzed procedure... 

Muramic acid analogues, e.g. 67, have been synthesized fipom the azide 65 via lactam 66 (Scheme 20). Oxazolidine derivatives reported earlier (Vol.26, Ch.9, ref.37) have been converted into conformationally restricted muramoyl dipeptide analogues. ... 

Critical amounts of cortex (a peptidoglycan layer of bacterial spores) are required for different properties of Bacillus sphaericus spores. Characteristic properties of the spores, such as the refractility and the resistance to xylene, octanol, and heat, were measured. Reduction with sodium borotritide and acid hydrolysis, etc., has been used to detect muramic lactam, which is located specifically in the cortical peptidoglycan of bacterial spores. The cortex content of several sporulation-deficient mutants of B. subtilis was examined using this procedure. 

---