Agilent 1260 series apparatus

The molecular weights of AjFG and dAjFG were determined by HPGPC using an Agilent 1260 series apparatus (Agilent Technologies, Santa Clara, CA, USA) equipped with a Shodex OH-pak SB-804 HQ column and a RID detector. Chromatographic procedures were performed according to previous method [25 (link)]. A standard curve of molecular weight was calculated with the SEC-Pullulan standards and calibrated with the dodecasaccharide obtained from the sea cucumber S. variegatus with known relative M_w [16 (link)]. The monosaccharide compositions were measured as described previously [35 (link)], and the PMP-labeled saccharides were analyzed by an Agilent 1260 HPLC system equipped with an Eclipse Plus C18 column (4.6 × 250 mm, 5 μm, Agilent) and a DAD detector. The -OSO³⁻ to -COO⁻ molar ratio of AjFG was determined by a conductimetric titration method [36 (link)]. The specific rotation of AjFG was detected by a polarimeter at the concentration of 0.5 mg/mL at 20 °C. The IR spectrum of AjFG was measured through KBr pellet by Bruker Tensor 27 infrared spectrometer (Ettlingen, Germany) at the range of 4000–400 cm⁻¹. Methylation of AjFG was carried out according to the literature [9 (link),10 (link)].

The homogeneity and molecular weight of PPP, PPP-1a, PPP-1b and PPP-2 were examined by high-performance gel permeation chromatography (HPGPC) using an Agilent 1260 series apparatus (Agilent Technologies, Santa Clara, CA, USA) equipped with a RID detector and a Shodex OH-pak SB-804 HQ or Shodex OH-pak SB-806 HQ column (8 mm × 300 mm). The column was eluted with 0.1 M NaCl solution at a flow rate of 0.5 mL/min at 35 °C. The HPLC system was calibrated by D-series dextran standards (D-2, D-3, D-4, D-5, D-6, D-7 and D-8) [9 (link)].