Characterization of β-Lactoglobulin Fibrillar Assembly Using Atomic Force Microscopy, Polyacrylamide Gel Electrophoresis, and in Situ Fourier Transform Infrared Spectroscopy

• Published in: Journal of agricultural and food chemistry Vol. 58; no. 6; pp. 3667 - 3673
• Main Authors: Oboroceanu, Daniela, Wang, Lizhe, Brodkorb, André, Magner, Edmond, Auty, Mark A. E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 24.03.2010
• Subjects: Biological and medical sciences; Electrophoresis, Polyacrylamide Gel; Environmental Chemistry; food analysis; Food industries; Fourier transform infrared spectroscopy; Fundamental and applied biological sciences. Psychology; lactoglobulins; Lactoglobulins - chemistry; microscopy; Microscopy, Atomic Force; Milk and cheese industries. Ice creams; polyacrylamide gel electrophoresis; polypeptides; protein aggregates; Protein Conformation; protein isolates; protein secondary structure; Spectroscopy, Fourier Transform Infrared; whey protein; self-assembly; SDS−PAGE; β-Lactoglobulin; proteins; AFM; peptides; ATR−FTIR; whey protein isolate; fibrils; STEM; Atomic force microscopy; Fourier transformation; Peptides; Gel electrophoresis; ATR-FTIR; In situ; Protein isolate; Stem; Characterization; Infrared spectrometry; SDS-PAGE; Milk protein; Whey protein
• ISSN: 0021-8561; 1520-5118; 1520-5118
• DOI: 10.1021/jf9042908

The aggregation process of β-lactoglobulin (β-lg) from 0 min to 20 h was studied using atomic force microscopy (AFM), scanning transmission electron microscopy (STEM), sodium dodecyl sulfate−polyacrylamide gel electrophoresis (SDS−PAGE), and in situ attenuated total reflectance−Fourier transform infrared spectroscopy (ATR−FTIR). Fibril assembly was monitored in real time using AFM up to 20 h. From 0 to 85 min, β-lg monomers deformed and expanded with some aggregation. After 85 min, fibrillar structures were formed, exceeding 10 μm in length. Fibrillar structures were confirmed by STEM. Secondary structural changes occurring during fibril formation were monitored by ATR−FTIR at 80 °C and indicated a decrease in α-helix content and an increase in β-sheet content. SDS−PAGE indicated that fibrils were composed of polypeptides and not intact monomers. In this study, β-lg and whey protein isolate (WPI)-derived fibrils, including some double helices, in water were observed by AFM under ambient conditions and in their native aqueous environment.