Jasmina C Cheung-Lau

Amherst College, Amherst Center, Massachusetts, United States

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Publications (6)19.15 Total impact

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    ABSTRACT: The microwave spectra of six isotopologues each of 2-chloro-1,1-difluoroethylene and its argon complex are obtained in the 5.6-20.5 GHz region using a combination of broadband chirped pulse and Balle-Flygare cavity Fourier transform microwave techniques. The structure of the halogen substituted ethylene has been determined using a combination of theory and experiment. Argon is found to form a nonplanar complex with this haloethylene, locating in the CICCF cavity, which maximizes its interactions with the heavy atoms in the ethylene subunit. A combined analysis of the chlorine quadrupole coupling constants of the monomer and of the complex allows the sign of the only nonzero off-diagonal component of the quadrupole coupling tensor for the monomer to be determined; thus, the complete tensor for the monomer has been derived.
    No preview · Article · Nov 2014 · Journal of Molecular Spectroscopy
  • Jasmina C Cheung-Lau · Dage Liu · Katherine W Pulsipher · Weiren Liu · Ivan J Dmochowski
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    ABSTRACT: The study of interactions between proteins and nanoparticles is important to advancing applications of nanoparticles in biology, medicine, and materials science. Here, we report the encapsulation of a 5-nm diameter gold nanoparticle (AuNP) by thermophilic ferritin (tF), achieved in nearly quantitative yield under mild conditions that preserved the secondary structure, ferroxidase activity, and thermal stability of the native, 4-helix bundle protein subunits. Chromatography-based assays determined that stable protein assembly around AuNPs occurred on long time scales (~48h) and was reversible. Apparent association constants were determined at 25°C for equilibrated tF-BSPP-capped AuNP samples (KA=(2.1±0.4)×10(78)M(-11)) and compared favorably to salt-assembled tF samples (KA=(2.2±0.5)×10(68)M(-11)) at the same protein concentration (0.3mg/mL). Finally, addition of gold ions and mild reducing agent to the tF-AuNP assembly produced 8-nm diameter AuNPs with surface plasmon resonance band unchanged at 520nm, indicative of templating by the protein shell.
    No preview · Article · Oct 2013 · Journal of inorganic biochemistry
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    ABSTRACT: Although sodium dodecyl sulfate (SDS) is widely used as an anionic detergent, it can also exert specific pharmacological effects that are independent of the surfactant properties of the molecule. However, structural details of how proteins recognize SDS are scarce. Here, it is demonstrated that SDS binds specifically to a naturally occurring four-helix bundle protein: horse apoferritin. The X-ray crystal structure of the apoferritin-SDS complex was determined at a resolution of 1.9 Å and revealed that the SDS binds in an internal cavity that has previously been shown to recognize various general anesthetics. A dissociation constant of 24 ± 9 µM at 293 K was determined by isothermal titration calorimetry. SDS binds in this cavity by bending its alkyl tail into a horseshoe shape; the charged SDS head group lies in the opening of the cavity at the protein surface. This crystal structure provides insights into the protein-SDS interactions that give rise to binding and may prove useful in the design of novel SDS-like ligands for some proteins.
    Full-text · Article · May 2012 · Acta Crystallographica Section D Biological Crystallography
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    ABSTRACT: A physiological relationship between iron, oxidative injury, and fatty acid metabolism exists, but transduction mechanisms are unclear. We propose that the iron storage protein ferritin contains fatty acid binding sites whose occupancy modulates iron uptake and release. Using isothermal microcalorimetry, we found that arachidonic acid binds ferritin specifically and with 60 μM affinity. Arachidonate binding by ferritin enhanced iron mineralization, decreased iron release, and protected the fatty acid from oxidation. Cocrystals of arachidonic acid and horse spleen apoferritin diffracted to 2.18 Å and revealed specific binding to the 2-fold intersubunit pocket. This pocket shields most of the fatty acid and its double bonds from solvent but allows the arachidonate tail to project well into the ferrihydrite mineralization site on the ferritin L-subunit, a structural feature that we implicate in the effects on mineralization by demonstrating that the much shorter saturated fatty acid, caprylate, has no significant effects on mineralization. These combined effects of arachidonate binding by ferritin are expected to lower both intracellular free iron and free arachidonate, thereby providing a previously unrecognized mechanism for limiting lipid peroxidation, free radical damage, and proinflammatory cascades during times of cellular stress.
    Preview · Article · Feb 2012 · The FASEB Journal
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    Brittani K Ruble · Julia L Richards · Jasmina C Cheung-Lau · Ivan J Dmochowski
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    ABSTRACT: DNA enzymes (DNAzymes) that catalyze the degradation of complementary RNA molecules have been investigated for many biochemical and sensing applications. Here, we investigated a 10-23 DNAzyme that has been shown previously to possess cellular activity. We determined that it has very low Mg(2+) ion dependence, with DNAzyme activity observed at [Mg(2+)] = 0.01 mM. This metal ion dependence is much lower than is typical for DNAzymes studied to date, and suggests that DNAzymes may be engineered for many additional biological applications. Recently, we demonstrated that this 10-23 DNAzyme can be divided into two parts, which assemble into an active oligonucleotide complex. We investigated in more detail the functionality of the split 10-23 DNAzyme and found that dividing the 15-nucleotide catalytic loop after the 7(th) or 8(th) base maximized its activity. The split DNAzymes required higher metal ion concentrations ([Mg(2+)] = 5 mM), and as we anticipated due to their lower hybridization activity, the split enzymes had the advantage of being more sensitive to single base mismatches in the DNAzyme-RNA duplex. Finally, we demonstrated facile photomodulation of split DNAzyme activity by incorporating a photocleavable biotin moiety bound to streptavidin.
    Full-text · Article · Jan 2012 · Inorganica Chimica Acta
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    ABSTRACT: Interfacing biological systems with inorganic nanoparticles is of great interest, as it offers means of particle stabilization and spatial control in electronic or biomedical applications. We report on the particle-directed assembly of hyperthermophile Archaeoglobus fulgidus ferritin subunits around negatively charged colloidal gold. An annealing process allows rapid assembly of the protein in near-native stoichiometry. Transmission electron microscopy suggests that greater than 95% of nanoparticles are encapsulated while the self-assembly process ensures that almost 100% of the assembled ferritin cavities are occupied.
    Full-text · Article · Apr 2009 · Langmuir

Publication Stats

46 Citations
19.15 Total Impact Points


  • 2014
    • Amherst College
      • Department of Chemistry
      Amherst Center, Massachusetts, United States
  • 2009-2013
    • University of Pennsylvania
      • • Department of Chemistry
      • • Department of Anesthesiology and Critical Care
      Filadelfia, Pennsylvania, United States
  • 2012
    • William Penn University
      Filadelfia, Pennsylvania, United States