Relation between Pore Sizes of Protein Crystals and Anisotropic Solute Diffusivities

Abstract

The diffusion of a solute, fluorescein, into lysozyme protein crystals with different pore structures was investigated. To determine the diffusion coefficients, three-dimensional solute concentration fields acquired by confocal laser scanning microscopy (CLSM) during diffusion into the crystals were compared with the output of a time-dependent 3-D diffusion model. The diffusion process was found to be anisotropic, and the degree of anisotropy increased in the order: triclinic, tetragonal and orthorhombic crystal morphology. A linear correlation between the pore diffusion coefficients and the pore sizes was established. The maximum size of the solute, deduced from the established correlation of diffusion coefficients and pore size, was 0.73 +/- 0.06 nm, which was in the range of the average diameter of fluorescein (0.69 +/- 0.02 nm). This proves that size exclusion is the key mechanism for solute diffusion in protein crystals. Hence, the origin of solute diffusion anisotropy can be found in the packing of the protein molecules in the crystals, which determines the crystal pore organization.

Crystalline Proteins as an Alternative to Standard Formulations

“…Furthermore, studies have to be conducted in order to evaluate the removal of ILs from the protein crystals. Here, the diffusive removal by simple washing of the crystals seems to be a possible promising pathway [28,29].…”

Multiplexed Cell-Counting Methods by Using Functional Nanoparticles and Quantum Dots

“…The majority of fluorescent dyes have a nonspherical shape. Fluorescein (FITC) is also a nonspherical solute with sizes of 0.47, 0.81, and 1.09 nm in different directions (Cvetkovic et al, 2005). Therefore, the size of fluorescent dye should be determined by using the appreciate method.…”

The Impact of Mesopores on Mass Transfer in Nanoporous Materials: Evidence of Diffusion Measurement by NMR

“…With the recently introduced techniques of single-molecule monitoring [11][12][13][14] individual molecules may be exploited as pore-space messengers. Thus, following the very diffusion path, molecular passages between different pore domains may be directly monitored [15][16].…”