The diffusion coefficient of lysozyme, a globular protein, was measured at various conditions as funcitions of lysozyme concentration, salt concentration, and solution ’age’ in concentrated, saturated, and supersaturated solutions, employing Gouy interferometry. Distilled water, 0.05M potassium phosphate buffer, and 0.1M sodium acetate buffer solutions with 0,2,4, and 5wt% NaCl were used as solvents. The pH of lysozyme solutions in distilled water was 4.75 due to the self-buffering capacity of lysozyme. The pH’s of the lysozyme solutions in the potassium phosphate and so-dium acetate buffers were adjusted to 6.8 and 4.0, respectively. The experimental temperature was 25℃. In a salt-free sys-tem, the concentration dependent diffusion of lysozyme showed typical electrolyte diffusion behavior, while a salt-po-lyelectrolyte system exhibited the behavior of a non-electrolyte. Diffusion results in the supersaturated region showed a lit-tle effect of concentration or solution ’age’ at a fixed NaCl concentration. A rapid decline in diffusion coefficient with in-creasing NaCl concentration in the supersaturated region, however, was observed.

Lysozyme Diffusivity Salt Supersaturation Interferometer

Alexandrowicz A, Daniel R, Biopolymers, 1, 447 (1963) 
Ataka M, Asai M, J. Cryst. Growth, 90, 86 (1988) 
Azuma T, Tsukamoto K, Sunagawa I, J. Cryst. Growth, 98, 371 (1989) 
Chang YC, "Concentration Dependent Diffusion of Solid-Solute Liquid-Solvent Systems in the Supersaturated Region," Ph.D. Dissertation, Georgia Institute of Technology (1985)
Chang Yc, Myerson AS, AIChE J., 31, 890 (1985) 
Chang YC, Myerson AS, AIChE J., 32, 1567 (1986) 
Daniel E, Alexandrowicz Z, Biopolymers, 1, 473 (1963) 
Doherty P, Benedek GB, J. Chem. Phys., 61, 5426 (1974) 
Dubin SB, Lunacek JH, Benedek GB, Proc. Natl. Acad. Sci., 57, 1164 (1967) 
Elgersma AV, Ataka M, Katsura T, J. Cryst. Growth, 122, 31 (1992) 
Ermak DL, J. Chem. Phys., 62, 4189 (1975) 
Howard SB, Twigg PJ, Baird JK, Meehan EJ, J. Cryst. Growth, 90, 94 (1988) 
Kedem O, Katchalsky A, J. Polym. Sci., 14, 321 (1955) 
Lee WI, Schurr JM, J. Polym. Sci., 13, 873 (1975)
Lo PY, "The Diffusion and Molecular Cluster Formation in Binary and Ternary Supersaturated Solutions," Ph.D. Dissertation, Polytechnic University (1991)
Marlowe RL, "A Study of the Concentration Dependence of Macromolecular Diffusion Using Photon Correlation Spectroscopy," Ph.D. Thesis, University of Cincinnati (1983)
Mikol V, J. Mol. Biol., 213, 187 (1989) 
Myerson AS, Lo PY, J. Cryst. Growth, 110, 26 (1991) 
Myerson AS, Senol D, AIChE J., 30, 1004 (1984) 
Pusey ML, J. Cryst. Growth, 110, 60 (1991) 
Pusey ML, J. Cryst. Growth, 122, 1 (1992) 
Raj T, Flygare WH, Biochemistry, 13, 3336 (1974) 
Sorell LS, "The Measurement of Diffusion Coefficients in Supersaturated Solution," M.S. Thesis, Georgia Institute of Technology (1981)
Tivant P, Drifford M, Magdelenat H, Menez R, Biopolymers, 22, 643 (1983) 
Varoqui R, Schmitt A, Biopolymers, 11, 1119 (1972) 
Vink H, J. Colloid Interface Sci., 135, 218 (1990)