Adsorption of Glycinin and beta-Conglycinin on Silica and Cellulose: Surface Interactions as a Function of Denaturation, pH, and Electrolytes

Carlos Salas, Orlando J. Rojas*, Lucian A. Lucia, Martin A. Hubbe, Jan Genzer

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

22 Citations (Scopus)

Abstract

Soybean proteins have found uses in different nonfood applications due to their, interesting properties. We report on the kinetics and extent of adsorption on silica and cellulose surfaces of glycinin and beta-conglycinin, the main proteins present in spy. Quartz crystal microgravimetry (QCM) experiments indicate that soy protein adsorption is strongly affected by changes in the physicochemical environment. The affinity of glycinin and the mass adsorbed on silica and cellulose increases (by ca. 13 and 80%, respectively) with solution ionic strength (as it increases from 0 to 100 mM NaCl) due to screening of electrostatic interactions. In contrast, beta-conglycinin adsorbs on the same substrates to a lower extent and the addition of electrolyte reduces adsorption (by 25 and 57%, respectively). The addition 01 10 mM 2-mercaptoethanol, a denaturing agent, reduces the adsorption of both proteins with a significant effect for glycinin. This observation is explained by the cleavage of disulfide bonds which allows unfolding of the molecules and promotes dissociation into subunits that favors more compact adsorbed layer structures. In addition, adsorption of glycinin onto cellulose decreases with lowering the pH from neutral to pH 3 due to dissociation of the macromolecules, resulting in flatter adsorbed layers. The respective adsorption isotherms fit a Langmuir model and QCM shifts in energy dissipation and frequency reveal multiple step kinetic processes indicative of changes in adlayer structure.

Original languageEnglish
Pages (from-to)387-396
Number of pages10
JournalBiomacromolecules
Volume13
Issue number2
DOIs
Publication statusPublished - Feb 2012
MoE publication typeA1 Journal article-refereed

Keywords

  • SOY PROTEIN FRACTIONATION
  • DRY-STRENGTH PERFORMANCE
  • SOYBEAN PROTEINS
  • IONIC-STRENGTH
  • SOLID-SURFACES
  • PHYSICAL PROPERTIES
  • MOLECULAR-STRUCTURE
  • CHEMICAL PROPERTIES
  • DISULFIDE BONDS
  • NEUTRAL SALTS

Fingerprint

Dive into the research topics of 'Adsorption of Glycinin and beta-Conglycinin on Silica and Cellulose: Surface Interactions as a Function of Denaturation, pH, and Electrolytes'. Together they form a unique fingerprint.

Cite this