Question

Human body is rich in protein digesting enzymes,but still the system cannot digest proteins like keratin. Why?

Answer 1

All the enzymes are bio-catalyst and active in soluble form. So keratin protein in cells is in both the soluble and insoluble form. However hair keratins are essentially insoluble in water. It's not true that humans don't have enzymes for digestion of keratin proteins. If one can make hair keratins in soluble form, humans can digest it with trypsin /pepsin