Question

we have pepsin,carboxy peptidase,amio peptidase,trypsin...etc protien digesting enzymes...
what are the difference in them... why we need all of them instead of any 1?

Answer 1

each cleaves peptides at different sites, ie different amino acids. as we have different aa bonds, each with its own spatial configuration, one needs different enzymes

Answer 2

As ttom said, the reason that we have multiple is because each of these proteases cleave polypeptides apart at different amino acid linkages; additionally, some are only active at the extremely low pH in the stomach, whereas others are active in the intestines, then others are active in the blood and such, so we need multiple to 1) cleave the different amino acids apart, and 2) to be active at the different environments in the body.