Screening of protein crystallization trials by second order nonlinear optical imaging of chiral crystals (SONICC)

Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47904, United States.
Methods (Impact Factor: 3.65). 11/2011; 55(4):379-86. DOI: 10.1016/j.ymeth.2011.11.003
Source: PubMed


Second order nonlinear optical imaging of chiral crystals (SONICC) is a promising new method for the sensitive and selective detection of protein crystals. Relevant general principles of second harmonic generation, which underpins SONICC, are reviewed. Instrumentation and methods for SONICC measurements are described and critically assessed in terms of performance trade-offs. Potential origins of false-positives and false-negatives are also discussed.

  • Source
    • "When a substantially intense electric field is produced by a laser pulse, molecular dipoles are induced. In the case of a chiral crystal, these induced dipoles are anisotropic on their potential energy surface and allow the sampling of nonlinear, even numbered higher order polarizability terms such as the second-generation harmonic (frequency doubling) (Haupert & Simpson, 2011). Enhanced signal can be measured at half the wavelength of the incident pulse, indicative of chiral crystals due to constructive interference provided by the ordered lattice. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Photosystem II (PSII) is a membrane protein supercomplex that executes the initial reaction of photosynthesis in higher plants, algae, and cyanobacteria. It captures the light from the sun to catalyze a transmembrane charge separation. In a series of four charge separation events, utilizing the energy from four photons, PSII oxidizes two water molecules to obtain dioxygen, four protons, and four electrons. The light reactions of photosystems I and II (PSI and PSII) result in the formation of an electrochemical transmembrane proton gradient that is used for the production of ATP. Electrons that are subsequently transferred from PSI via the soluble protein ferredoxin to ferredoxin-NADP(+) reductase that reduces NADP(+) to NADPH. The products of photosynthesis and the elemental oxygen evolved sustain all higher life on Earth. All oxygen in the atmosphere is produced by the oxygen-evolving complex in PSII, a process that changed our planet from an anoxygenic to an oxygenic atmosphere 2.5 billion years ago. In this chapter, we provide recent insight into the mechanisms of this process and methods used in probing this question. © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Dec 2015 · Methods in enzymology

  • No preview · Article · Dec 2011 · Methods
  • [Show abstract] [Hide abstract]
    ABSTRACT: A symmetry-additive ab initio model for second-harmonic generation (SHG) activity of protein crystals was applied to assess the likely protein-crystal coverage of SHG microscopy. Calculations were performed for 250 proteins in nine point-group symmetries: a total of 2250 crystals. The model suggests that the crystal symmetry and the limit of detection of the instrument are expected to be the strongest predictors of coverage of the factors considered, which also included secondary-structural content and protein size. Much of the diversity in SHG activity is expected to arise primarily from the variability in the intrinsic protein response as well as the orientation within the crystal lattice. Two or more orders-of-magnitude variation in intensity are expected even within protein crystals of the same symmetry. SHG measurements of tetragonal lysozyme crystals confirmed detection, from which a protein coverage of ∼84% was estimated based on the proportion of proteins calculated to produce SHG responses greater than that of tetragonal lysozyme. Good agreement was observed between the measured and calculated ratios of the SHG intensity from lysozyme in tetragonal and monoclinic lattices.
    No preview · Article · Nov 2012 · Acta Crystallographica Section D Biological Crystallography
Show more