title: Quantifying anisotropic solute transport in protein crystals using 3-D laser scanning confocal microscopy visualization.
abstract: The diffusion of a solute, fluorescein into lysozyme protein crystals has been studied by confocal laser scanning microscopy (CLSM). Confocal laser scanning microscopy makes it possible to non-invasively obtain high-resolution three-dimensional (3-D) images of spatial distribution of fluorescein in lysozyme crystals at various time steps. Confocal laser scanning microscopy gives the fluorescence intensity profiles across horizontal planes at several depths of the crystal representing the concentration profiles during diffusion into the crystal. These intensity profiles were fitted with an anisotropic model to determine the diffusivity tensor. Effective diffusion coefficients obtained range from 6.2 x 10(-15) to 120 x 10(-15) m2/s depending on the lysozyme crystal morphology. The diffusion process is found to be anisotropic, and the level of anisotropy depends on the crystal morphology. The packing of the protein molecules in the crystal seems to be the major factor that determines the anisotropy.
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Cvetkovic
authors.forename: A J J
authors.initials: AJ
authors.lastname: Straathof
authors.forename: D N
authors.initials: DN
authors.lastname: Hanlon
authors.forename: S
authors.initials: S
authors.lastname: van der Zwaag
authors.forename: R
authors.initials: R
authors.lastname: Krishna
authors.forename: L A M
authors.initials: LA
authors.lastname: van der Wielen
mesh_terms: D001692:Biological Transport; D003460:Crystallization; D004058:Diffusion; D019793:Fluorescein / Q000737:chemistry* / Q000378:metabolism*; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D021621:Imaging, Three-Dimensional / Q000379:methods; D018613:Microscopy, Confocal / Q000379:methods*; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D009113:Muramidase; D019793:Fluorescein