Thermal Dependence of Thermally Induced Protein Spherulite Formation and Growth: Kinetics of β-lactoglobulin and Insulin

• Published in: Biomacromolecules 2007-12, Vol.8 (12), p.3930-3937
• Main Authors: Domike, Kristin R, Donald, Athene M
• Format: Article
• Language: English
• Subjects: Animals; Applied sciences; Biological and medical sciences; Cattle; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hot Temperature; In solution. Condensed state. Thin layers; Insulin - pharmacokinetics; Insulin - physiology; Lactoglobulins - chemistry; Lactoglobulins - pharmacokinetics; Molecular biophysics; Natural polymers; Physico-chemical properties of biomolecules; Physicochemistry of polymers; Protein Conformation; Proteins
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm7009224

Amyloid fibril forming proteins have been related to some neurodegenerative diseases and are not fully understood. In some such systems, these amyloid fibrils have been found to form radially oriented spherulite structures. The thermal dependence of formation and growth of these spherulite structures in two model protein systems, β-lactoglobulin and insulin at low pH aqueous and high temperature conditions, have been monitored with time-lapse optical microscopy and quantified. A population-based polymerization reaction model was developed and applied to the experimental data with excellent agreement. While spherulites in the insulin solutions formed and grew at approximately 25× the rate of spherulites in the β-lactoglobulin solutions, the temperature dependence and activation energies of both systems were found to be very similar to one another, suggesting that the underlying rate-limiting mechanisms for both formation and growth are consistent across the two systems. The similarity of both of these amyloid fibril forming protein systems provides confidence in their use as model systems for extrapolating understanding to similar systems involved in neurodegenerative diseases.