Do Sulfhydryl Groups Affect Aggregation and Gelation Properties of Ovalbumin?

• Published in: Journal of agricultural and food chemistry Vol. 54; no. 14; pp. 5166 - 5174
• Main Authors: Broersen, Kerensa, Van Teeffelen, Annemarie M. M, Vries, Anneke, Voragen, Alphons G. J, Hamer, Rob J, De Jongh, Harmen H. J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.07.2006
• Subjects: acetylmercaptosuccinic anhydride; beta-lactoglobulin; Biological and medical sciences; Chemical Phenomena; Chemistry, Physical; disulfide bonds; Disulfides - chemistry; Electrophoresis, Polyacrylamide Gel; Food industries; Fundamental and applied biological sciences. Psychology; gelation; Gels - chemistry; globular-proteins; heat-induced aggregation; high-pressure; interchange reactions; Kinetics; Microscopy, Electron; ovalbumin; Ovalbumin - chemistry; protein aggregates; protein-protein interactions; rheological properties; Rheology; Sulfhydryl Compounds - chemistry; sulfhydryl groups; thermal aggregation; whey-protein isolate; Ovalbumin; Deformation; Rheology; Gelation; gel properties; sulfhydryl groups; large and small deformation rheology; Aggregation; disulfide bonds; Transmission electron microscopy; cryo-TEM; Disulfide bond; Rheological properties
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0601923

The aim of this work is to evaluate the impact of sulfhydryl groups on ovalbumin aggregation and gelation. Ovalbumin was chemically modified to add sulfhydryl groups in various degrees. The rate of aggregation was not affected by the introduction of sulfhydryl groups, and disulfide bond formation was preceded by physical interactions. Hence, disulfide interactions may not be the driving force for the aggregation of ovalbumin. Investigation of the aggregates and gels by electron microscopy and rheology suggested that a critical number of sulfhydryl groups can be introduced beyond which the microstructure of the aggregates transforms from fibrillar into amorphous. Rheological studies further suggested that covalent networks, once formed, do not have the possibility to rearrange, reducing the possibility to attain a stronger network. These results show that, even though aggregation of ovalbumin may be primarily driven by physical interactions, formed disulfide bonds are important to determine the resulting aggregate morphology and rheological properties. Keywords: Ovalbumin; aggregation; gel properties; sulfhydryl groups; disulfide bonds; large and small deformation rheology; cryo-TEM