The effects of pH, temperature, and buffer concentration on the self-assembling behavior, secondary structure, and surface hydrophobicity of donkey and bovine β-casein

Jingjing Zhang; Silvia Vincenzetti; Paolo Polidori; Valeria Polzonetti; Alessandro Di Michele; Diego Romano Perinelli; Guiqin Liu; Lanjie Li; Stefania Pucciarelli

doi:10.1016/j.foodchem.2023.137285

The effects of pH, temperature, and buffer concentration on the self-assembling behavior, secondary structure, and surface hydrophobicity of donkey and bovine β-casein

Food Chem. 2024 Feb 1:433:137285. doi: 10.1016/j.foodchem.2023.137285. Epub 2023 Aug 30.

Authors

Jingjing Zhang¹, Silvia Vincenzetti², Paolo Polidori³, Valeria Polzonetti⁴, Alessandro Di Michele⁵, Diego Romano Perinelli⁶, Guiqin Liu⁷, Lanjie Li⁸, Stefania Pucciarelli⁹

Affiliations

¹ School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 62032 Camerino, MC, Italy; College of Agronomy, Shandong Engineering Technology Research Center for Efficient Breeding and Ecological Feeding of Black Donkey, Shandong Donkey Industry Technology Collaborative Innovation Center, Liaocheng University, 252000 Liaocheng, Shandong, China. Electronic address: [email protected].
² School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 62032 Camerino, MC, Italy. Electronic address: [email protected].
³ School of Pharmacy, University of Camerino, Via Gentile da Varano, 62032 Camerino, MC, Italy. Electronic address: [email protected].
⁴ School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 62032 Camerino, MC, Italy. Electronic address: [email protected].
⁵ Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, PG, Italy. Electronic address: [email protected].
⁶ School of Pharmacy, University of Camerino, Via Gentile da Varano, 62032 Camerino, MC, Italy. Electronic address: [email protected].
⁷ College of Agronomy, Shandong Engineering Technology Research Center for Efficient Breeding and Ecological Feeding of Black Donkey, Shandong Donkey Industry Technology Collaborative Innovation Center, Liaocheng University, 252000 Liaocheng, Shandong, China. Electronic address: [email protected].
⁸ College of Agronomy, Shandong Engineering Technology Research Center for Efficient Breeding and Ecological Feeding of Black Donkey, Shandong Donkey Industry Technology Collaborative Innovation Center, Liaocheng University, 252000 Liaocheng, Shandong, China. Electronic address: [email protected].
⁹ School of Biosciences and Veterinary Medicine, University of Camerino, Via Gentile III da Varano, 62032 Camerino, MC, Italy. Electronic address: [email protected].

PMID: 37683474
DOI: 10.1016/j.foodchem.2023.137285

Abstract

The self-assembling behavior, secondary structure, and surface hydrophobicity of purified donkey β-casein in terms of pH, temperature, and buffer concentration were investigated in comparison with commercial bovine β-casein. Critical micelle concentration of both β-caseins decreased with the lowering of pH (pH 8.0-6.0) and the increasing temperatures (25-50 °C). Critical micelle temperature of both β-caseins increased moving from pH 6.0 to 8.0 and aggregates larger than micelles formed at pH 6.0 that is close to their isoelectric point. Fluorescence spectroscopy analysis demonstrated that the maximum surface hydrophobicity was achieved at pH 6.0. The secondary structure was examined using circular dichroism spectroscopy, highlighting an increase of α-helix content and a decrease of unordered structures with the decrease of pH and increase of temperature. This work provides insights on parameters promoting molecular interactions involved in donkey β-CN self-association, useful to develop nanocarriers for encapsulating bioactive compounds in pharmaceutical and nutraceutical applications.

Keywords: Critical micelle concentration; Critical micelle temperature; Donkey β-casein; Secondary structure; Surface hydrophobicity.