Quantification of Binary Diffusion in Protein Crystals

Abstract

The use of confocal laser scanning microscopy for visualization and quantification of binary diffusion within anisotropic porous material is described here for the first time. The dynamics of adsorption profiles of dianionic fluorescein, zwitterionic rhodamine B, and their mixture in the cationic native orthorhombic lysozyme crystal were subsequently analyzed. All data could be described by a classical pore diffusion model. There was no change in the adsorption characteristics, but diffusion decreased with the introduction of a second solute in the solution. It was found that diffusion is determined by the combination of steric and electrostatic interactions,while adsorption is dependent on electrostatic and hydrophobic interactions. Thus, it was established that the outcome of binary transport depends on the solute, protein, and crystal characteristics.

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].…”

Post‐Crystal Engineering of Zinc‐Substituted Myoglobin to Construct a Long‐Lived Photoinduced Charge‐Separation System

“…[17][18][19] Anisotropic diffusion of small molecules in hen egg-white lysozyme (HEWL) crystals has been investigated by experimental and simulation approaches. [21,22] The results suggest that these features are governed by steric repulsion and electrostatic interaction induced by amino acid residues located on the internal surface of the crystal lattices. Thus, if we can precisely arrange donor and acceptor molecules and mediators in protein crystals, it is expected that the novel three-dimensional framework will allow us to achieve a longlived charge-separated state.…”

“…[1,31] The fixation of Ru 3 O clusters in the hydrophobic crevices is expected to decrease the reorganization energy of the Ru 3 O cluster and allow rapid electron transfer of MVC + !Ru 3 O + and slow recombination of ZnPC + /Ru 3 O 0 !ZnP/Ru 3 O + (Figure 1). [3,14,30] The lifetimes of the interprotein pathway at SiteB (21 ) and at SiteA (22 ) and the intraprotein pathway at SiteB (23 ) were found to be 2.8 ms, 3.3 ms, and 41 ms, respectively, according to the distance between ZnPC + and Ru 3 O 0 in the crystal lattice (Figure 3 a). The distance decay constant of these pathways (b = 1.3 À1 ) is satisfied with the coupling zone of proteins reported by Gray et al, [32] wherein the driving force and the reorganization energy of Ru 3 O are assumed to be the same for SiteA and SiteB (see Supporting Information).…”

“…[14][15][16] Moreover, protein crystals provide nanosized spaces for the fixation of metal ions, metal complexes, and the diffusion of organic molecules. [17][18][19][20][21][22] For instance, accumulation of metal ions and metal complexes in a protein crystal lattice spaces was accomplished simply by soaking of the crystals in a solution containing their precursors. [17][18][19] Anisotropic diffusion of small molecules in hen egg-white lysozyme (HEWL) crystals has been investigated by experimental and simulation approaches.…”

“…On the other hand, although the unambiguous positions of MV molecules were not determined by X-ray crystal structure analysis, positively charged MV molecules are expect to diffuse around ZnP and Ru 3 O in the crystal because the negatively charged binding sites of ZnP and Ru 3 O govern the diffusion of MV molecules in the crystal channels, as reported for the Cl À ion/HEWL crystal system (Figure 3 b). [21,22] It is suggested that the unique diffusion of MV in the crystal plays an essential role in mediating ET between ZnP and Ru 3 O to extend charge separation, in contrast to the fixation of Trp122, which facilitates multistep electron tunneling, in an intramolecular Re-Trp-Cu(azurin) photosystem. [1,31] The fixation of Ru 3 O clusters in the hydrophobic crevices is expected to decrease the reorganization energy of the Ru 3 O cluster and allow rapid electron transfer of MVC + !Ru 3 O + and slow recombination of ZnPC + /Ru 3 O 0 !ZnP/Ru 3 O + (Figure 1).…”