Determination of the Refractive Index Increment for Binary Mixtures of Albumin and Gamma-Globulin
Tamara M. Innokenteva¹, Victoria V. Gibizova¹; ¹Federal State Budgetary Educational Institution of Higher Education "Lomonosov Moscow State University", Moscow, Russia
Abstract
This work presents the results of an experimental determination of the refractive index increment for binary mixtures of human serum albumin and γ-globulin. Measurements were performed using an ITR-2 interferometer at a wavelength of 550 nm and a temperature of 20 °C. For individual albumin, the obtained dn/dc value is in good agreement with literature data. For albumin–γ-globulin mixtures, it was established that the experimental dn/dc values are not described by a simple additive model, indicating the presence of intermolecular interactions between the components. The deviation from additivity depends on the component ratio: a positive deviation observed for the 1:1 mixture suggests aggregate formation, while negative deviations are found for the 1:2 and 2:1 mixtures. These findings are interpreted within the framework of the excess increment concept arising from specific intermolecular interactions. The results highlight the necessity of accounting for non-additive optical behavior when interpreting light-scattering data in multicomponent protein systems.
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Tamara M. Innokenteva
Lomonosov Moscow State University
Россия
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