The amino acid compositions of HS and EpSSs were analyzed
using HPLC (HP1100, USA). Each sample was hydrolyzed by 6N
hydrochloric acid with 0.02 vol.% 2-mercaptoethanol at 110 ◦C for
24 h in a nitrogen filled vial. The final hydrolysates were dissolved
in pH 2.2 sodium citrate buffers and analyzed by HPLC using an
Inno-C18 column. The column temperature was 40 ◦C and the flow
rate was 1ml/min.