Details

Autor(en) / Beteiligte

• Erickson, Daniel P.
• Ozturk, Oguz K.
• Selling, Gordon
• Chen, Feng
• Campanella, Osvaldo H.
• Hamaker, Bruce R.

Titel

Corn zein undergoes conformational changes to higher β-sheet content during its self-assembly in an increasingly hydrophilic solvent

Ist Teil von

• International journal of biological macromolecules, 2020-08, Vol.157, p.232-239

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2020

Quelle

MEDLINE

Beschreibungen/Notizen

• Viscoelasticity of corn zein is associated with the formation of β-sheet secondary structures; however, studies of the fundamentals of this conformational change are limited due to zein insolubility and poor analytical resolution. Here, changes in soluble zein conformation were evaluated as the protein self-assembles in increasingly hydrophilic solvents to the concentration just before aggregation and precipitation. Circular dichroism spectra of zein showed that α-helix structures decrease in favor of random coil and β-sheets with increases in water content in an ethanol-water system, similar to observations of zein when it becomes viscoelastic in dough systems. This was further supported by changes in Thioflavin T fluorescence emission spectra and intrinsic viscosity measurements. Two widely recognized molecular models for α-zein (hairpin and superhelical conformations) were tested at 75 and 45% ethanol concentration using molecular dynamics simulation for agreement with experimental results. Increase in solvent hydrophilicity increased β-sheets and reduced distance between backbone anomeric carbons only for hairpin model, suggesting it to be the more valid of the two. These findings emphasize the importance of transformation to β-sheets during zein self-assembly and provide further insight into the mechanisms by which the protein is functionalized into viscoelastic systems. •Changes in zein conformation were evaluated in an increasingly hydrophilic solvent.•α-Helix decreased in favor of random coil and β-sheets with increase in water content.•Findings were supported by Thioflavin T emission spectra and viscosity measurement.•Hairpin and superhelical conformations were tested using molecular dynamics simulation.•Hairpin structural model accurately described the increase in β-sheet content.