*2.6. Carbohydrate Analyses*

Chondroitin and chondbiuronan were quantified by colorimetric assay of uronic acid [16]. Average molecular weight and molecular weight distributions were determined using high-performance size-exclusion chromatography (HPSEC) (LC-20AD, Shimadzu, Marne La Vallée, France) with on-line multi-angle light scattering (MALS) (MiniDAWN TREOS, Wyatt Technology Corp. (Santa Barbara, CA, USA)) fitted with a K5 cell and a laser wavelength of 660 nm, a refractive index detector, and a viscometer. Columns (OHPAK SB-G guard column and OHPAK SB 806 HQ column (Shodex, Munich Germany) were eluted with 0.1 M NaNO<sup>3</sup> containing 0.03% NaN<sup>3</sup> at 0.5 mL·min−<sup>1</sup> . Solvent and samples were filtered through 0.1 µm and 0.2 µm filter units (Merck-Millipore, Darmstadt, Germany), respectively. The dn/dc determined with a refractometer was of 0.1306 and 0.1293 for chondbiuronan and chondroitin, respectively. <sup>13</sup>C and <sup>1</sup>H-NMR spectra were recorded with a BRUKER Avance 400 spectrometer (Ettlingen, Germany) operating at a frequency of 100.618 MHz for <sup>13</sup>C and 400.13 MHz for <sup>1</sup>H. Samples were solubilized in D2O and analysed at 353 K. Residual signal of the solvent was used as an internal standard: mono-deuterated water (HOD) at 4.25 ppm.

MALDI-TOF(-TOF)-MS: Matrix solution was prepared by dissolving 100 mg of 2,5-dihydroxybenzoic acid (DHB) in 1 mL of a 1:1 solution of water and acetonitrile then 20 µL of N,N-dimethylaniline (DMA) were added to the DHB matrix solution. The analyte (10 mg/mL in water) and DHB/DMA solutions were mixed (1:1) and spotted onto a polished steel MALDI target, then dried at ambient temperature. The MALDI mass analysis were performed in linear negative ion mode with an Autoflex Speed TOF/TOF spectrometer (BrukerDaltonics, Bremen-Lehe, Germany) equipped with a 355 nm Smartbeam II laser.
