title: Intercalating dyes for enhanced contrast in second-harmonic generation imaging of protein crystals.
abstract: The second-harmonic generation (SHG) activity of protein crystals was found to be enhanced by up to ∼1000-fold by the intercalation of SHG phores within the crystal lattice. Unlike the intercalation of fluorophores, the SHG phores produced no significant background SHG from solvated dye or from dye intercalated into amorphous aggregates. The polarization-dependent SHG is consistent with the chromophores adopting the symmetry of the crystal lattice. In addition, the degree of enhancement for different symmetries of dyes is consistent with theoretical predictions based on the molecular nonlinear optical response. Kinetics studies indicate that intercalation arises over a timeframe of several minutes in lysozyme, with detectable enhancements within seconds. These results provide a potential means to increase the overall diversity of protein crystals and crystal sizes amenable to characterization by SHG microscopy.
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Newman
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Scarborough
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Pogranichniy
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Rashmi K
authors.initials: RK
authors.lastname: Shrestha
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Closser
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Chittaranjan
authors.initials: C
authors.lastname: Das
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA.
authors.forename: Garth J
authors.initials: GJ
authors.lastname: Simpson
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry; D000818:Animals; D002645:Chickens; D004396:Coloring Agents / Q000032:analysis*; D003460:Crystallization / Q000379:methods; D019286:Endopeptidase K / Q000737:chemistry; D008853:Microscopy / Q000379:methods; D009113:Muramidase / Q000737:chemistry; D061848:Optical Imaging / Q000379:methods; D011506:Proteins / Q000737:chemistry*; D012394:Rosaniline Dyes / Q000032:analysis*; D012568:Schizosaccharomyces / Q000737:chemistry; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D011506:Proteins; D012394:Rosaniline Dyes; D029702:Schizosaccharomyces pombe Proteins; C005095:malachite green; D009113:Muramidase; D019286:Endopeptidase K; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase
keywords: SHG; dye; high-throughput screening; protein crystals