title: Purification and characterization of D-Gal-6-sulfurylase from Eucheuma striatum.
abstract: D-Gal-6-sulfurylase catalyzing the conversion of μ-carrageenan into κ-carrageenan was extracted from Eucheuma striatum and purified by ammonium sulfate precipitation, hydrophobic interaction chromatography and ion exchange chromatography. The purified enzyme was a monomeric protein with a molecular mass of about 65 kDa as shown in SDS-PAGE. The maximum activity of the enzyme was observed at pH 7.0 and temperature 40°C. Km value for μ-carrageenan was 4.31 mM, and the corresponding Vmax was 0.17 mM min(-1). The carrageenan treated with 10 U of the purified enzyme exhibited 7.1-fold increase in gel strength with a removal of 30% sulfate groups. (1)H NMR spectral analysis of the control and enzyme treated carrageenan confirmed the conversion of μ- into κ-carrageenan and highlighted the specificity of Gal-6-sulfurylase for μ-carrageenan. This Gal-6-sulfurylase provides an eco-friendly and alternative for alkali treatment method to produce high gel strength κ-carrageenan.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Qin
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Ma
authors.forename: Zaixiang
authors.initials: Z
authors.lastname: Lou
authors.forename: Aimei
authors.initials: A
authors.lastname: Wang
authors.forename: Hongxin
authors.initials: H
authors.lastname: Wang
mesh_terms: D020418:Algal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002351:Carrageenan / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D019906:Nuclear Magnetic Resonance, Biomolecular; D000461:Rhodophyta / Q000201:enzymology*; D013429:Sulfatases / Q000737:chemistry* / Q000302:isolation & purification; D013696:Temperature
chemical_list: D020418:Algal Proteins; D002351:Carrageenan; D013429:Sulfatases