Publisher Summary The chapter describes the understanding of the physics and physical chemistry of sickle cell hemoglobin polymerization in solutions and in red cells. The polymerization of sickle cell hemoglobin has probably become the best understood of all protein self-assembly systems. The structure of the hemoglobin S molecule, the structure of the various aggregated forms of hemoglobin S, and the structural analysis of the polymers are discussed in the chapter. The chapter discusses the thermodynamics of hemoglobin S polymerization, and includes a description of the nonideal behavior of concentrated hemoglobin S solutions and the effects of physiologically relevant variables, especially oxygen, and the presence of non-S hemoglobins on the polymerization process. Understanding the polymerization process is not only important for understanding the pathophysiology of sickle cell disease, but is critical to the major problem of developing a specific therapy that could be used in the treatment of patients. The kinetic and thermodynamic studies have played a major role by providing relevant and sensitive assays for potential therapeutic agents. The results of the thermodynamic and kinetic studies of solutions are used to explain various properties of cells, including morphological and rheological properties.

Sickle cell hemoglobin polymerization.

http://light.ece.illinois.edu/ECE564/Research_Projects_files/FLIM_Clegg.pdf

Fluorescence lifetime imaging microscopy (FLIM): Spatial resolution of microstructures on the nanosecond time scale

Fluorescence lifetime imaging microscopy (FLIM) : Spatial resolution of microstructures on the nanosecond time scale

Alignment maps of tissues: I. Microscopic elliptical polarimetry.

Differential scattering of incident left and right circularly polarized light can be an important contribution to the circular dichroism of macromolecules. In principle both differential absorption and differential scattering of circularly polarized light contribute to circular dichroism, but differential scattering is increasingly important for particles whose dimensions are greater than 1/20th the wavelength of light. The scattering contribution is probably not important for unaggregated proteins and nucleic acids in solution. It can be very important for viruses, membranes, and other protein-nucleic acid complexes. Outside the absorption bands of the scattering, chiral particle, only differential scattering contributes to the circular dichroism. The sign and magnitude of the differential scattering is quantitatively related to the relative orientations and the distances between the scattering units of the particle. The interpretation of the circular differential scattering depends on a simple, classical method. Thus, in understanding a measured circular dichroism, it often will be easier to relate the differential scattering to the structure of a particle (such as a virus) than it is to relate the differential absorption to the structure.

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Circular differential scattering can be an important part of the circular dichroism of macromolecules (optical activity/circularly polarized light/nucleic acids)

Differential polarization imaging. III. Theory confirmation. Patterns of polymerization of hemoglobin S in red blood sickle cells

This study represents the first systematic attempt to characterize the possible sources of artifacts that can interfere with the measurement of circular intensity differential scattering (CIDS) as a function of the scattering angle. A theoretical analysis of the effect of imperfect incident circular polarizations in the measurement of baselines from nonchiral scatterers and in the signals from chiral samples is derived. From this analysis the requirements of the tolerance on the quality of the incident circular polarizations to unequivocally measure the CIDS effect are established. The protocol for alignment of the CIDS instrument and the characterization of the incident polarizations utilized in these studies are described in detail. CIDS measurements on suspensions of helical sperm cells are presented. The experimental results are modeled computationally with the use of the current CIDS theory. Good agreement between the data and the computations is obtained. The results clearly indicate the ability of CIDS to provide information on the long-range chiral organization of samples in solution.

An analysis of circular intensity differential scattering measurements: studies on the sperm cell of Eledone cirrhosa.

A polarization modulation microscope designed to detect and spatially resolve the distribution of optically anisotropic domains in microscopic objects is described. An image dissector camera is used as the detection device. The polarization of the light is modulated by means of a photoelastic modulator and a synchronous demodulation amplifier (lock‐in) is utilized to obtain the difference image between the images formed using two orthogonal forms of the incident polarization on the sample. Preliminary results are described for the linear dichroism imaging measurements of polymerized hemoglobin (HbS) in red blood sickle cells. The present limitations of this design are discussed along with various strategies to improve its performance.

Differential polarization microscope using an image dissector camera and phase‐lock detection

We have applied the recently developed technique of circular intensity differential scattering (CIDS) to the study of oriented liquid crystals. The chirality of the liquid crystals and the ease of manipulation of their helical parameters make them an ideal system for investigating the dependence of the CIDS pattern on handedness and pitch. We have studied both right- and left-handed liquid crystals of pitch from 460 nm to 4 microns, with the helix axis oriented either parallel (planar orientation) or perpendicular (focal conic orientation) to the incident beam. The results showed that CIDS is sensitive to the handedness of the helix, for when two liquid crystals of the same pitch but opposite handedness were compared, the signs of their respective CIDS patterns were reversed.

K. S. Wells

Papers

Differential polarization imaging. III. Theory confirmation. Patterns of polymerization of hemoglobin S in red blood sickle cells

An analysis of circular intensity differential scattering measurements: studies on the sperm cell of Eledone cirrhosa.

Differential polarization microscope using an image dissector camera and phase‐lock detection

Circular Intensity Differential Scattering Measurements of Planar and Focal Conic Orientations of Cholesteric Liquid Crystals