Proteinases nutrition

Japanese Society of Miso Science and Technology Figure 18. Schematic representation of effect of heat treatment on soybean protein and its hydrolysis patterns by various enzymes. Pattern A, pepsin and other acid proteinoses pattern B, the proteinoses having an optimum near neutrality, such as papain, bacteria neutral proteinase, Aspergillus alkaline proteinase, Aspergillus neutral proteinase and pattern C, trypsin and in vivo nutritional... 

Pirie A, Werb Z, and Burleigh M (1975) Collagenase and other proteinases in the cornea of the retinol deficient rat. British Journal of Nutrition 34, 297-309. 

A proteinase-catalyzed reaction including splitting and synthesis of peptide bonds is a process also suitable for covalent amino acid incorporation into peptide chains. This type of enzymatic modification reaction of food proteins is useful for different purposes alteration of sensory properties, solubility, nutritional quality, functional properties, antifreeze character, and different biological activities. Recently, special proteinase-catalyzed reactions have been elaborated by which proteins can be modified with particular respect to their primary structure and conformation. 

Soybeans are swollen and ground in the presence of a 10-fold excess of water. Heating the suspension close to its boiling point for 15-20 min pasteurizes the suspension and inactivates lipoxygenase enzyme and proteinase inhibitors. A soy milk preparation enriched with calcium and vitamins is of importance in infant nutrition as a replacement for cow s milk, which close to 7% of infants in the USA are unable to tolerate. 

The second difficulty listed above can be at least partly resolved. Specific inhibitors or additional proteinases can be inserted into cells by the same liposome method and the effects on the degradation assessed. Even this would not be necessary if the compounds were of sufficiently low molecular weight to permeate the cell membrane. Alternatively, conditions can be sought whereby the activity of a degrading enzyme is altered by nutritional or hormonal changes or perhaps in genetically deficient cell lines. However, it is possible, even likely, that degradation is not limited by proteinases until their activities have been very markedly reduced. 

---