EMULSIFIER OF ARTHROBACTER RAG-1 - CHEMICAL AND PHYSICAL-PROPERTIES

The extracellular emulsifier of Arthrobacter RAG-1 was deproteinized by hot phenol treatment and purified by fractional precipitation with (NH4)2SO4. The active fraction, precipitating between 30-35% saturation [EF-RAG(UET)WA], appeared to be homogeneous by immunodiffusion and sedimentation analysis. EF-RAG(UET)WA had an intrinsic viscosity of 750 cm3/g, a sedimentation constant of 6.06S, a diffusion constant of 5.25 .times. 10-8 cm2 s-1 and a partial molar volume of 0.712 cm3 g-1. From these data a weight average MW of 9.76 .times. 105 and a viscosity average MW of 9.88 .times. 105 were calculated. EF-RAG(UET)WA contained 46.7% C, 7.01% H and 6.06% N. Titration of the nonreducing polymer gave a single inflection point (pK'' = 3.05), corresponding to 1.5 .mu.mol of carboxyl groups/mg. Direct estimation of O-ester and hexose content of the highly acidic polymer yielded 0.65 and 0.29 .mu.mol/mg, respectively. Mild alkaline hydrolysis released fatty acids with an average MW of about 231. Strong acid hydrolysis of EF-RAG(UET)WA yielded D-glucose (minor), D-galactosamine (major) and an unidentified amino uronic acid (major).