Macromolecular changes and nano-structural arrangements in gliadin and glutenin films upon chemical modification: Relation to functionality.
Protein macromolecules adopted for biological and bio-based material functions are known to develop a structured protein network upon chemical modification. In this study, we aimed to evaluate the impact of chemical additives such as, NaOH, NH4OH and salicylic acid (SA), on the secondary and nano-structural transitions of wheat proteins. Further, the effect of chemically induced modifications in protein macromolecular structure was anticipated in relation to functional properties. The gliadin-NH4OH-SA film showed a supramolecular protein organization into hexagonal structures with 65 Å lattice parameter, and other not previously observed structural entities having a characteristic distance of 50 Å. Proteins in gliadin-NH4OH-SA films were highly polymerized, with increased amount of disulfide crosslinks and β-sheets, causing improved strength and stiffness. Glutenin and WG proteins with NH4OH-SA showed extensive aggregation and an increase in β-sheet content together with irreversible crosslinks. Irreversible crosslinks hindered a high order structure formation in glutenins, and this resulted in films with only moderately improved stiffness. Thus, formation of nano-hierarchical structures based on β-sheets and disulfide crosslinks are the major reasons of high strength and stiffness in wheat protein based films.
Department of Plant Breeding, The Swedish University of Agricultural Sciences, SE-230 53, Box 101, Alnarp, Sweden. Electronic address: Faiza.Rasheed@slu.se.
Faiza
F
Rasheed
Department of Plant Breeding, The Swedish University of Agricultural Sciences, SE-230 53, Box 101, Alnarp, Sweden.
William R
WR
Newson
MAX IV Laboratory, Lund University, Box 118, SE-221 00 Lund, Sweden.
Tomás S
TS
Plivelic
Department of Plant Breeding, The Swedish University of Agricultural Sciences, SE-230 53, Box 101, Alnarp, Sweden.
Ramune
R
Kuktaite
KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, SE-10044 Stockholm, Sweden.
Mikael S
MS
Hedenqvist
Innventia, Box 5604, SE-11486 Stockholm, Sweden.
Mikael
M
Gällstedt
Department of Plant Breeding, The Swedish University of Agricultural Sciences, SE-230 53, Box 101, Alnarp, Sweden.
Eva
E
Johansson
D064753:Ammonium Hydroxide / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D005903:Gliadin / Q000737:chemistry* / Q000302:isolation & purification; D005983:Glutens / Q000737:chemistry* / Q000302:isolation & purification; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry*; D058105:Polymerization; D066329:Protein Aggregates; D017433:Protein Structure, Secondary; D020156:Salicylic Acid / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D013718:Tensile Strength; D014908:Triticum / Q000737:chemistry*
D004220:Disulfides; D008567:Membranes, Artificial; D066329:Protein Aggregates; D064753:Ammonium Hydroxide; D012972:Sodium Hydroxide; D005983:Glutens; D005903:Gliadin; C037302:glutenin; D020156:Salicylic Acid
Gliadin; Glutenin; Hexagonal morphology; Molecular crosslinking