CHAPTER 



ENZYMIC DEGRADATION 

 AND BIOSYNTHESIS 

 OF MICROBIAL WALLS 



Enzymic Degradation 



From some of the unusual features of the chemical prop- 

 erties of microbial cell walls outlined in Chapter 2 it is now 

 easy to understand why they resist many of the proteolytic 

 enzymes so active in degrading intracellular proteins and 

 the various enzymes capable of breaking down lipids, poly- 

 saccharides, and other cellular constituents. The resistance 

 of bacterial cell walls to proteolytic enzymes is especially 

 conspicuous, and even if it was purely fortuitous that the 

 D-isomers of amino acids were formed into wall peptides 

 it seems eminently sensible that they should be there. Al- 

 though many microbial walls are unattacked by enzymes 

 degrading the intracellular structures and constituents, they 

 can, as already pointed out, be attacked by enzymes pro- 

 duced by the cells themselves and by a variety of enzymes 

 from other microorganisms and from other cells and tissues. 



>\/gae. Fungi, Yeasts. The gut of the snail provides a 

 collection of enzymes that have been used in degrading the 



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