Main content area

Low molecular weight proteins from sunflower (Helianthus annuus L.) seed: effect of acidic butanol treatment on the physicochemical properties

Venktesh, A., Prakash, V.
Journal of agricultural and food chemistry 1993 v.41 no.2 pp. 193-198
sunflower seed, plant proteins, molecular weight, butanol, acidity, chlorogenic acid, molecular conformation, polyacrylamide gel electrophoresis, fluorescence emission spectroscopy, protein secondary structure
Sunflower seed protein interactions with chlorogenic acid (CGA) result in unfavorable color development. CGA is shown to be more associated with the low molecular weight proteins (LMW). This can alter the properties of the protein, especially the LMW proteins. The sedimentation coefficient of the LMW proteins remained unchanged at 1.8 S. The protein resolved into four peaks on Sephadex G-75 gel filtration. The composition of the second fraction increased from 35% to 53% upon acidic butanol treatment. The last fraction had higher amounts of CGA. The native polyacrylamide gel electrophoresis indicated fast moving bands, but the molecular weights of the three major bands did not change, as seen in SDS-polyacrylamide gel electrophoresis as a result of acidic butanol treatment. The secondary structure of the protein was 19% alpha-helix, 40% beta-structure, and 41% aperiodic for the native and 27% alpha-helix, 38% beta-structure, and 35% aperiodic for the acidic butanol treated protein. The fluorescence emission maximum indicated a red shift from 330 nm, indicating structural alterations of the proteins.