Fractionation and characterization of glycoproteins containing hydroxyproline from the leaves of Vicia faba.

Abstract

A survey was conducted of the distribution, solubility, chemical and some physical properties of the constituents of the leaves of Vicia faba containing hydroxyproline. With aqueous trichloroacetic acid about 30% of the total leaf hydroxyproline could be brought into solution. The rest remained insoluble in aqueous or non-aqueous solvents tested under non-hydrolytic conditions. The material soluble in trichloroacetic acid was resolved by phenol-aqueous (pH 8) partitioning into (a) predominantly polysaccharide-type materials with small amounts of firmly bound proteins containing hydroxyproline; (b) into some insoluble material and (c) into glycoproteins and glycolipids containing hydroxyproline soluble in the phenol-rich phase. These last were separated into at least four cationic, one anionic and one stationary components on continuous high voltage electrophoresis in phenol–acetic acid–water. The four cationic glycoprotein fractions were resolved further on the basis of their size on a Bio Gel P 100 column operated in phenol–acetic acid–water. The stationary component was composed of a mixture of glycolipids and contained strongly bound amino acids including hydroxyproline. Analytical results for the major components obtained in this work clearly indicated the presence in the leaves of Vicia faba of a number of glycoproteins, polysaccharide-protein complexes and glycolipids containing hydroxyproline each with characteristic and different composition, molecular size and solubility. Previous work on cell-wall protein (extensin) was discussed in the light of these results.