Characterization of albumin-binding properties of Peptostreptococcus magnus

A Peptostreptococcus magnus strain demonstrated binding activity for albumin preparations from humans, mice, and dogs, but not for rabbit or bovine albumin. The albumin binding site appeared to be heat stable and of protein nature. Treatment of P. magnus cells with trypsin under specified conditions enhanced this albumin binding. Electron micrographs and kinetic analyses revealed that this enhancement was the result of the removal of some cell wall associated proteins leading to a higher binding affinity without significant changes in binding site numbers. The albumin-binding proteins could be readily solu-bilized and purified by affinity chromatography. Upon gel electrophoresis the molecular mass of the albumin-binding proteins was estimated as 130 kilodaltons.Key words: Peptostreptococcus magnus, albumin binding, trypsin enhancement.