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Keywords:

  • free-solvent model;
  • solvent accessible surface area;
  • SASA;
  • osmotic pressure;
  • hemoglobin;
  • beta-lactoglobulin;
  • alpha-crystallin;
  • ion binding;
  • hydration

Abstract

Here, we provide an algorithm that predicts solvent accessible surface area (SASA) using concentrated solution osmotic pressure data. Sheep hemoglobin monomer and β-lactoglobulin are used for verification. Additionally, SASA for structurally unknown calf lens α-crystallin aggregate is predicted. Using osmotic pressure data, the predicted SASA value for sheep hemoglobin, 22,398 ± 1,244 Å2, was in excellent agreement with computational model predictions (24,304 Å2-26,100 Å2). Similarly, predicted SASA values for bovine β-lactoglobulin in pH solutions of pH 5.1, 6.0, and 8.0, were 5,765 ± 1,031 Å2, 6,656 ± 1,082 Å2, and 9,141 ± 1,060 Å2, respectively, were in good agreement with the computationally determined SASA value (7,500 Å2–8,628 Å2). Predicted SASA for the aggregate of calf lens α-crystallin (800 kDa) was found to be 417,691 ± 16,790 Å2. These results illustrate that this novel method can provide an important experimental alternative in estimating SASA for proteins and, possibly, their complexes in solution. © 2011 American Institute of Chemical Engineers AIChE J, 2012