Isolation and partial characterization of proteins from pea (Pisum sativum L.)

Abstract

AbstractPea flour with a protein content (Nx6,25) of 25% was subjected to an extraction by 10% NaCl. The changes of the meal particles during the extraction were studied by electron microscopy. 89% of the nitrogen substances were extracted, 14% of which are albuminsThe nitrogen solubility curve of the meal has a minimum of 18% solubility at pH 4‐5The proteins in the NaCl extract were fractionated using dialysis (separation of globulins and albumins) and preparative gel chromatography (separation of the 11 S and 7 S globulins). The 11 S and 7 S globulins were homogenous in gel chromatography and ultracentrifugation. Their sedimentation coefficients s020 w were 11,9 S and 6,4 S, respectively. They differ significantly in the gel electrophoresisThe amino acid composition of the isolated globulins shows a relatively high content of glutamin and aspartic acid as well as arginine and a lack of sulphur containing amino acids which are limiting. EAA indices of 69, 63, 62, 32 and 78 were calculated for pea flour, the raw globulin fraction, the 11 S and 7 S fraction, and the albumine fraction, respectively. Therefore for preserving the nutritive value of the pea material preparation processes are to be applied which exclude the loss of albumins during the protein isolation.