Collagen trypsin attack

This work also points to the fact that the hexoses are bound to collagen, and the fact that they occur in the more unassailable regions of the collagen molecule suggests that they may take part in the cross-links. Hormann (1960a) has pictured trypsin attack as in Pig. 11. 

Denatured collagen, as formed post-mortem by the action of lactic acid, can also be cleaved by lysosomal enzymes, e. g., lysosomal collagenase and cysteine proteinase cathepsin Bi. Thermally denatured collagen is attacked by pepsin and trypsin. 

The aim of this study was to verify previous conclusions that dentin collagen resists enzymatic attack after reaction with glucose. The results show that, following the Maillard reaction, dentin collagen indeed is less degraded by pepsin, but not by trypsin. 

Factors such as fiber diameter, compactness, and the difficult solubility of collagen would seem of importance in determining such properties as resistance to hydrolytic attack by enzymes. This inertness is probably not entirely derived from the chemistry of collagen but depends also on physical factors which prevent an enzyme from gaining access to its substrate. Pepsin, acting under acid conditions on swollen fibrils, is able to cause degradation (195), and increased temperature or physical maceration facilitates even the attack by trypsin in neutral or slightly alkaline environments (194, 200). 

Fibrous proteins that have supporting or protective function in the animal, of which there are three types (1) collagens in the skin, tendons and bones, which are resistant to pepsin and trypsin, and are converted to water-soluble gelatin by boiling with water (2) elastins in the tendons and arteries, which are not converted to gelatin and (3) ceratins, which comprise the horns, hoofs, feathers, scales, and nails, and which are insoluble in dilute acids and alkalis and are not attacked by any animal digestive enzymes. 

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