Nanomechanical force measurements of gliadin protein interactions

Abstract

The strength and nature of interactions between monomeric gliadin proteins involving alpha-alpha, omega-omega, and alpha-omega interactions in 0.01M acetic acid, and the effect of urea has been investigated. It was shown by means of nanomechanical force measurements that the stretching events in the separation curve after adhesive phenomena originated from proteins. These stretching events displayed different responses of the alpha- and omega-gliadins to urea. While 2M urea caused the more globular alpha-gliadins to unfold, the beta-turn-rich omega-gliadins remained fairly stable even in 8M urea. This suggests different roles for gliadins in the formation of dough; while the omega-gliadins are still in a compact structure being responsible for the viscous flow, the alpha-gliadins have already started to participate in forming the network in dough.

Microstructure of hydrated gluten network

“…However, mixing of α-and ω-gliadins results in phase-separated bicontinuous morphology depending on the composition of the mixtures and the conditions of mixing (McMaster, Miles, Wannerberger, Eliasson, Shewry & Tatham, 1999). Differences in the modes of interactions between α-and ω-gliadins may play key role in determining network formation and mechanical properties of gluten (Paananen, Tappura, Tatham, Fido, Shewry, Miles et al, 2006). These observations show that the complexity in the composition of gliadin fraction results in various structures depending on the specific set of circumstances leading up to visualization.…”

Biochemical and Functional Properties of Wheat Gliadins: A Review

“…However, gliadins are still widely considered to adopt a globular protein structure in 70% aqueous ethanol (Foulk and Bunn, 2001). But recent researches reveal that α/β-gliadins have compact globular structures and γ -and ω-gliadins have extended and rod-like structures (Paananen et al, 2006;Ang et al, 2010).…”

Rheological behavior of wheat gliadins in 50% (v/v) aqueous propanol

“…Higher hydration to 47% water content would induce irreversible structure changes on heating (Georget and Belton, 2006). Two molar urea caused more globular a-gliadins to unfold while the b-turnrich x-gliadins remained fairly stable even in 8 M urea (Paananen et al, 2006). Rheological test has been employed to study hydrated gliadins (Khatkar et al, 2002) and gliadin suspensions (Xu et al, 2007), and to probe the function of gliadins in wheat flour and gluten doughs (Martling et al, 2004).…”

“…Conformations and molecular interactions of wheat storage proteins have been extensively investigated using various techniques such as atomic force microscopy (AFM) (McIntire et al, 2005;McMaster et al, 2000McMaster et al, ,1999Paananen et al, 2006), Raman optical activity (ROA) (Blanch et al, 2003), Fourier transform infrared (FTIR) spectroscopy (Feeney et al, 2003;Georget and Belton, 2006;Li et al, 2006;Pezolet et al, 1992), 1 H magic angle spinning nuclear magnetic resonance (MAS NMR) (Alberti et al, 2001), small angle X-ray scattering (SAXS) (Thomson et al, 1999), circular dichroism (CD) spectroscopy (Kieffer et al, 2007), and intrinsic viscosity measurement (Cole et al, 1984;Ewart, 1980;Field et al, 1987). The interaction between layers of a-gliadin has been studied by the surface force technique (Wannerberger et al, 1997).…”