Effect of Salts on Protein Aggregation and Ice Nucleation Efficiency

ROYA SAFA, Sarah D. Brooks, Daniel Thornton, Texas A&M University

     Abstract Number: 531
     Working Group: Bioaerosols

Abstract
Biological aerosols can act as highly efficient immersion ice nuclei by catalyzing freezing events at warmer temperatures than other ice nucleating particles. Our research indicates protein nucleation efficiency is modulated by concentration, aggregation, divalent cations, and electrostatic interactions. Measurement of ice nucleation and zeta potential showed that higher protein concentrations enhance ice nucleation activity through a greater surface area provided by higher repulsive electrostatic interactions. In addition, protein aggregation as measured by dynamic light scattering, can be altered by interactions with metal cations, which in turn affect the ice nucleation activity. This study examines the effects of the most abundant seawater divalent cations (Mg²⁺, Ca²⁺, and Sr²⁺) on the aggregation size and ice nucleation properties of select proteins (cytochrome c, Snomax®, RuBisCo and thyroglobulin). RuBisCo maintained high ice nucleation efficiency even as ionic strength increased, highlighting its uniqueness in ice nucleation activity. Notably, thyroglobulin demonstrated exceptional stability, with consistent aggregation sizes across varying cationic ionic strengths. These findings provide valuable insights into the role of proteins and ice nucleation processes.