Phosphorylation of Ovalbumin by Dry-Heating in the Presence of Pyrophosphate:  Effect on Protein Structure and Some Properties

• Published in: Journal of agricultural and food chemistry Vol. 53; no. 12; pp. 4962 - 4967
• Main Authors: Li, Can-Peng, Hayashi, Yoko, Shinohara, Hiroshi, Ibrahim, Hisham R, Sugimoto, Yasushi, Kurawaki, Junichi, Matsudomi, Naotoshi, Aoki, Takayoshi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.06.2005
• Subjects: Biological and medical sciences; Calorimetry, Differential Scanning; Chemical Phenomena; Chemistry, Physical; denaturation; differential scanning calorimetry; Diphosphates - chemistry; Drug Stability; electrophoretic mobility; Food industries; food processing; Fundamental and applied biological sciences. Psychology; heat treatment; Hot Temperature; Humidity; Hydrogen-Ion Concentration; hydrophobicity; ovalbumin; Ovalbumin - chemistry; Phosphorylation; protein phosphorylation; protein secondary structure; pyrophosphates; Differential scanning calorimetry; Ovalbumin; Phosphorylation; Temperature; denaturation temperature; Denaturation; circular dichroism; Properties; Protein; structural properties; Heating; dry-heating; phosphorylatlon; Structure
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf047793j

Ovalbumin (OVA) was phosphorylated by dry-heating in the presence of pyrophosphate at pH 4.0 and 85 °C for 1 and 5 days, and the physicochemical and structural properties of phosphorylated OVA were investigated. The phosphorus content of OVA increased to 1.01% by phosphorylation, and the electrophoretic mobility of PP-OVA also increased. Although the solubility of dry-heated OVA decreased, the decrease was slightly depressed by phosphorylation. The circular dichroism spectra showed that the change of the secondary structure in the OVA molecule, as measured by α-helix content, was mild by phosphorylation. The exchange reaction between the sulfhydryl and disulfide groups was enhanced and the surface hydrophobicity of OVA increased by phosphorylation. The tryptophan fluorescence intensity of OVA decreased by phosphorylation, suggesting that the conformational change occurred in the OVA molecule by phosphorylation. Although the differential scanning calorimetry thermograms of OVA showed a lowering of the denaturation temperature from 78.3 to 70.1 °C by phosphorylation, the stability of OVA against heat-induced insolubility at pH 7.0 was improved. The results indicated molten (partially unfolded) conformations of OVA formed by dry-heating in the presence of pyrophosphate. Keywords: Ovalbumin; dry-heating; phosphorylation; structural properties; denaturation temperature; circular dichroism; differential scanning calorimetry