“…Cathepsin D isolated from herring, mackerel and cod exhibits the highest activity against haemoglobin at pH 2.5, 3.0 and 4.0, respectively (Jiang, Her, Lee, & Wang, 1993;McLay, 1980;Nielsen & Nielsen, 2001;Wang, Stenvik, Larsen, Maehre, & Olsen, 2007). Komai, Kawabata, Amano, Lee, and Ichishima (2004) demonstrated that the optimum pH of cathepsin D activity against synthetic substrate was lower by 0.5 units than against haemoglobin.…”