Simplified purification of chondroitin sulphate from scapular cartilage of shortfin mako shark (Isurus oxyrinchus)

Chondroitin sulphate (ChS) from the scapular cartilage of the shortfin mako shark (Isurus oxyrinchus) was purified by two-stage enzymatic hydrolysis and a fractional precipitation process using isopropyl alcohol. Characteristics of the ChS fraction were investigated using cellulose acetate membrane electrophoresis and FT-IR spectra. A maximum hydrolysis rate of 78.26% was achieved with 1.35% (w/w) Alcalase and 1.20% (w/w) Flavourzyme. A minimum nitrogen content of 2.89% was obtained with 1.43% (w/w) Alcalase and 1.33% (w/w) Flavourzyme, as determined by response surface methodology. The precipitation of ChS from the enzymatic hydrolysates was optimised at 40% (v/v) isopropyl alcohol, which contained 2% (w/v) NaCl to lower the nitrogen content. The precipitate was further purified via membrane filtration (molecular-weight cut-off, 3 kDa) to remove salt and low-molecular-weight materials. The ChS purified by enzymatic hydrolysis, isopropyl alcohol precipitation and membrane filtration was identified as ChS C by electrophoresis and FT-IR spectra.