Pepsin is an endopeptidase that breaks down proteins into smaller peptides.It is one of three principal proteases in the human digestive system, the other two being chymotrypsin and trypsin.
Pepsin digests 3000 - 3500 times it's weight of coagulated egg albumin.(1 pepsin unit will digest 3000 units coagulated egg albumin at 52°C, pH 2-3, no time involved.)