Electrophoresis was performed at 60 V. After electrophoresis,
the gels were placed in a 0.25 mol/L potassium
Next, subunit bands were excised and washed with pure water till they became transparent.
The excised bands of collagen subunits were minced and 400 mL
of Solution A (1 mg/mL PVPP and 2 mg/mL b-mercaptoethanol in
acetone solution containing 10 mL/100 mL trifluoroacetic acid)
from a PAGE gel trace protein extraction kit [Sangon Biotech
(Shanghai) Co., Ltd.)] was added. Samples were incubated for 18 h,
next extraction samples were transferred to centrifuge tubes, and