Size-exclusion Chromatography of Cancer Sera

Size-exclusion chromatography was performed as described previously [32 (link),33 (link)]. In brief, 200 μL of sera from MDS, breast, prostate cancer patients and blood donors was diluted to 1:1 in a buffer containing 0.01 M Hepes, 0.15 M NH₄Cl and 0.02% NaN₃ prior to injection into a Superose 12 column (1.0 × 30 cm, GE Health care, Sweden). The column was equilibrated with the same buffer and eluted at flow rate of 0.4 mL/min. Twenty four fractions (0.4 mL) were collected, and the TK1 protein content in the fractions determined and compared with standards of different molecular weights: α2-macroglobulin (720 kDa), β amylase (200 kDa), bovine serum albumin (66 kDa), ova albumin (45 kDa) and horse myosin (17 kDa).