Fifty micro liters of CZ1127 fucoidanase solution containing 20 mM Tris–HCl (pH 7.2) was mixed with 50 mL 0.4% fucoidan solution in the same buffer and 0.8 M NaCl. This mixture was incubated at 25 °C for 8 h and thereafter heated at 100 °C for 10 min. After centrifugation, the supernatant was desalted by non-por-ous graphitised carbon black column as previously reported (Packer, Lawson, Jardine, & Redmond, 1998). In brief, oligosaccharide solutions were applied to a Carbograph SPE column (SUPELCO, USA). Salts were washed with approximately three column volumes of water. The oligosaccharides were adsorbed and then eluted with 25% (v/v) acetonitrile in 0.05% (v/v) TFA, which was collected, concentrated and lyophilised.
2.3. Determination of oligosaccharide profile by LC–MS
The oligosaccharide profile was determined by high performance liquid chromatography (Aglient 1260, Aglient Technologies,USA) coupled with triple quadrupole mass spectrometry (Aglient
6400, Aglient Technologies, USA) according to the modified method of Alvarez-Manilla et al. (2006). The desalted oligosaccharide mixture was subjected to size exclusion chromatography (SEC) using a Superdex Peptide column (GE Healthcare, USA) eluted at a flow rate of 0.5 mL/min with 25% (v/v) acetonitrile containing 50 mM ammonium formate. Parameters for the MS were as follows: gas temperature 350 °C; gas flow, 11 L/min; nebuliser pressure, 50 psi; capillary voltage, 4000 V; fragmentor voltage, 135 V; scanned mass, 100–2000 Da. The data acquisition for MS signals was made using Chemstation software (B.04.00 [B4038], Aglient Technologies, USA) and the distribution coefficient of oligosaccharide, i, on Superdex Peptide column was calculated according to the following equation: