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Dissociation and aggregation of pea legumin induced by pH and ionic strength
Author(s) -
Gueguen J,
Chevalier M,
And J Barbot,
Schaeffer F
Publication year - 1988
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740440208
Subject(s) - legumin , ionic strength , chemistry , dissociation (chemistry) , tyrosine , ionic bonding , tryptophan , chromatography , biochemistry , storage protein , organic chemistry , ion , aqueous solution , amino acid , gene
The effect of pH and ionic strength on the association and dissociation phenomena of pea 11S‐type globulin (legumin) was investigated. It was shown by ultracentrifugation and HPLC that the native conformation was maintained only in the pH range 7 to 9. At extreme acidic or basic pH most of the molecules were dissociated. Below pH 3.4 the 12 S native form was completely dissociated, and at pH 2.4 only very slow sedimenting components (3.5S) were observed. At low ionic strength aggregation usually occurred. These results were confirmed by UV difference spectroscopy, and it was observed that acidic conditions induced a drastic dissociation of legumin leading to completely unfolded subunits. In this conformation all the tyrosine and tryptophan residues were exposed as shown by second derivative spectra. This spectroscopic study led also to hypotheses on the native structure of legumin and especially on the respective positions of the basic and acidic polypeptides.