A New Member of Family 11 Polysaccharide Lyase, Rhamnogalacturonan Lyase ( Ct RGL f ) from Clostridium thermocellum

A thermostable, alkaline rhamnogalacturonan lyase (RG lyase) Ct RGL f , of family 11 polysaccharide lyase from Clostridium thermocellum was cloned, expressed, purified and biochemically characterised. Both, the full-length Ct RGL f (80 kDa) protein and its truncated derivative Ct RGL (63.9 kDa) were expressed as soluble proteins and displayed maximum activity against rhamnogalacturonan I (RG I). Ct RGL f showed maximum activity at 70 °C, while Ct RGL at 60 °C. Both enzymes showed maximum activity at pH 8.5. Ct RGL f and Ct RGL do not show higher activity on substrates with high β- d -galactopyranose ( d -Gal p ) substitution, this catalytic property deviates from that of some earlier characterised RG lyases which prefer substrates with high d -Gal p substitution. The enzyme activity of Ct RGL f and Ct RGL was enhanced by 1.5 and 1.3 fold, respectively, in the presence of 3 mM of Ca 2+ ions. The TLC analysis of the degraded products of RG I, released by the action of Ct RGL f and Ct RGL revealed the production of RG oligosaccharides as major products confirming their endolytic activity.