ENZYMIC DEGRADATION AND BIOSYNTHESIS 59 



Streptomyces enzymes studied by Ghuysen.^ One of these 

 enzymes (Streptomyces F^) is essentially an N-acetyl-hexo- 

 saminidase ^^ and is therefore similar to egg-white lysozyme; 

 another enzyme (Streptomyces Fsb), an amidase/^ liberates 

 the peptide moiety from low molecular weight mucopep- 

 tides obtained from walls by lysozyme action. ^^ 



Lysozyme. Although it has been known that lysozyme 

 action on the isolated soluble substrates (usually obtained 

 by chemical fractionation of whole cells) involved the rup- 

 ture of glycosidic bonds with a liberation of N-acetylamino 

 sugar compounds/^' ^*^'^' direct evidence establishing the 

 nature of the linkages broken has become available only 

 in recent years. i-' ^^ The investigation of the nature of the 

 action of lysozyme became simplified when isolated cell 

 walls could be used as "substrate." ^^ Using the isolated 

 cell walls of several sensitive organisms, Salton ^o investi- 

 gated the nature of the products formed on digestion with 

 lysozyme. A complex mixture of fragments resulted, and 

 these fragments were separated into the larger, nondialyz- 

 able compounds of about 10,000 to 20,000 molecular weight. 

 These compounds possessed terminal groups of N-acetyl- 

 amino sugars and contained all of the constituents present 

 in the original wall (but probably in different propor- 

 tions -°). About half the original wall of Micrococcus lyso- 

 deikticus became diffusible upon dissolution with lysozyme. 

 The nature of the diffusible products was investigated, and 

 the most conspicuous "small fragment" detectable was a 

 compound containing glucosamine and muramic acid, prob- 

 ably in the form of a disaccharide.^o This substance was 

 detected in digests of all three cell walls studied, those of 

 Bacillus megaterium, Micrococcus lysodeikticus, and Sar- 

 cina lutea. Evidence suggested that both amino groups of 

 the amino sugars were acetylated and that the disaccharide 

 possessed a free carboxyl group— that of muramic acid. It 



