Substrate specificity of the β-1, 4-N-acetylglucosaminidases of vertebrates

A true chitinase, i.e. a poly-β-1, $\text{4-N-}\text{acetylglucosaminidase}$ specific of the hydrolosis of chitin and thus devoid of any lysozymic activity, has been localized in the gastric mucosa extracts and/or in the pancreas extracts of some vertebrate species (frog, lizard and mammals), the diet of which contains chitin. This observation confirms the relation existing between the feeding habits of vertebrates and the ability to synthesize specific chitinolytic enzymes. Furthermore, chitinolytic activity bound to lysozomic activity has been observed in the extracts of other organs such as the spleen of the carp and the kidneys of the dog, the rabbit and the ferret. In these cases, the chitinolytic activity seems to be due to the presence of lysozymes with different degrees of activity on the β-1, $\text{4-N-}\text{acetylglucosaminic}$ bounds of chitin.