Rapeseed protein — polyanion interactions. Soluble complexes between the 2 S protein fraction (napin) and phytic acid

✍ Scribed by Mothes, R. ;Schwenke, K. D. ;Zirwer, D. ;Gast, K.

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 648 KB
• Volume: 34
• Category: Article
• ISSN: 0027-769X
• DOI: 10.1002/food.19900340422

✦ Synopsis

The formation of electrostatic complexes between the low molecular mass basic rapeseed protein fraction . (napin) and phytic acid was studied using turbidimetry, potentiometry, gel chromatography, gel electrophoresis, dynamic light scattering and circular dichroism spectroscopy.

In the first step insoluble "substoichiometric" complexes are formed in which the positive charge of the protein are not completely neutralized. Soluble negatively charged oligomeric complexes are formed with an excess of phytic acid. Protein dimers dominate over the monomer and small amounts of higher oligomers. Dimers and larger soluble aggregates are the main components after heating. The critical phytic acid-protein ratio for solubilizing the system represents the threshold value for the heat-stabilkkg effect of phytic acid. Complexing with phytic acid does not influence significantly the secondary structure of the protein. Buffers and neutral salts weaken the phytic acid binding to the protein and decrease the molecular mass of the complexes.