Isolation and partial characterization of the exocellular polysaccharides of Penicillium charlesii: II. The occurrence of phosphate groups in high molecular weight polysaccharides

Abstract

Growth of Penicillium charlesii G. Smith on a medium containing 32P orthophosphate followed by chromatography of the medium on DEAE-Sephadex (borate form) resulted in the isolation of three polysaccharide fractions each labeled significantly with 32P. Spectrophotometric analyses indicated that substances absorbing in the region 260–280 mμ were eluted from DEAE-Sephadex with the polysaccharide fractions. The substances in each of the polysaccharide fractions were passed onto Sephadex G-50. Most of the 32P eluted with the polysaccharide fractions in the void volume of Sephadex G-50. Nearly all of the absorbing components eluted later as small molecular weight fractions. Treatment of intact 32P-labeled polysaccharides with either alkaline phosphatase or phosphodiesterase released no 32P orthophosphate nor did it decrease the sedimentation velocity of the polysaccharide. Paper chromatography of mild acid hydrolysates of all three fractions showed the presence of 32P-labeled orthophosphate together with labeled compounds migrating like hexose phosphates.