Keratan Sulphate Hydrolases

An enzyme that degrades keratan sulphate, porcine colonic mucin, and milk oligosaccharides has been isolated from E. Desialylized, porcine colonic 

Laminarinase activity has been detected in culture filtrates of Penicillium lilacinum.  

The ability of Rhizopus arrhizus laminarinase to hydrolyse reduced Sill pneumococcal polysaccharide distinguishes it from other jS-D-glucan hydrolases. Laminaribiose is the principal product, although the corresponding tetra-, hexa-, and octa-saccharides, each having a 3-substituted D-glucosyl residue at the reducing end, are formed transiently. 

An enzyme (mol. wt. 2.7 x 10 ) that hydrolyses jS-D-glucans and lichenan, but neither laminarin nor carboxymethylcellulose, has been obtained in partially purified form from a strain of Bacillus pumius it cleaves a /9-(l - 4)-linkage next to a jS-(l - 3)-linkage in these polymers. It was suggested that enzymes of this type should be named lichenanases to distinguish them from cellulases and laminarinases. 

The ability of Bacillus subtilis lichenanase to hydrolyse reduced Sill pneumococcal and other polysaccharides distinguishes it from other /3-D-glucan hydrolases. The enzyme behaved as a laminarinase (see above) towards the reduced Sill polysaccharide. 

Extracts of Actinobacillus and Pseudomonas species each catalysed extensive hydrolysis of corneal keratan sulphate, due to the combined actions of a 2-acetamido-2-deoxy-D-glucose 6-sulphate sulphatase, an exo-D-galactanase, an exro-jS-D-acetamidodeoxyglucanase, and an unidentified e/idb-glycosidase.  

Bacillus subtilis lichenase hydrolysed lichenin, oat glucan, and reduced pneumococcal type III polysaccharide. Unlike laminarinase, the enzyme did not degrade laminarin and carboxymethyl-laminarin. 

A reference work on lysosymes has dealt with their structures, the structural bases of enzymic and non-enzymic characteristics, and biological and clinical investigations.  

Human monocytes and mouse peritoneal macrophages have been shown to synthesize and secrete large amounts of lysozyme. Synthesis of the enzyme was rapidly inhibited by cycloheximide and less rapidly by colchicine. The physicochemical properties of this lysozyme were reported. 

Lysozyme in human sera, cerebrospinal and amniotic fluids, urine, saliva, gastric juice, bile, tears, milk, and sperm have been examined by means of diffusion in agarose gel. The enzyme is found in most body fluids, the highest activity occurring in tears. The level of lysozyme activity in human sera has been shown to increase after exercise, but to drop to the original level during recovery. Possible mechanisms for these changes were discussed. 

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The biological significance of chitosan biomaterials in the hiunan body depends largely on the actions that certain hydrolases exert on them. The resulting chitoohgomers stimulate various cells, while the released monomers are phosphorylated and incorporated into hyaluronan, keratan sulphate and chondroitin sulphate, components of the intracellular matrix and connective tissue [348]. 

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