An Extracellular α-L-Arabinofuranosidase secreted by Sclerotinia fructigena

Abstract

AN earlier communication¹ reported the resolution of a maceration factor from endopolygalacturonase (PG) in culture filtrates of Sclerotinia fructigena Aderh. and Ruhl., by means of gel filtration on dextran Sephadex ‘G 75’ and chromatography on ‘Ecteola’-cellulose. The biochemical basis of maceration of potato slices by these preparations was not elucidated, but McClendon² has demonstrated that, in chromatography on cellulose phosphate of an ultra-filtered and freeze-dried sample of our culture filtrate, maceration of potato disks occurred in two peaks, one associated with a major PG peak and the other with a minor PG peak, with indications that arabanase or galactanase may macerate. We have shown independently that arabinose is liberated from potato fibre by a purified ‘maceration factor’ preparation free of PG and, subsequent to McClendon's findings, from lupin seed pectate. Incubation of the purified preparation with potato fibre was also accompanied by a release of soluble uronide, as determined by the carbazole method³ (Fig. 1); the uronide was shown to be of high molecular weight by its failure to pass through a ‘Visking’ dialysis membrane, suggesting that a partial breakdown of in soluble ‘protopectin’ had occurred.