Our staff maintains and operates a battery of sophisticated solution-based biophysical instrumentation. Among the analytical methods available to intramural researchers are: analytical ultracentrifugation (AUC), isothermal titration calorimetry (ITC), surface plasmon resonance (SPR), differential scanning calorimetry (DSC), dynamic light scattering (DLS), circular dichroism spectroscopy (CD), and asymmetric flow field-flow fractionation (AF4). Accuracy and precision in AUC are critical to properly characterize protein samples. Our collaboration with Peter Schuck and Huaying Zhao resulted in the development of new devices to monitor temperature measurements of the rotor and accurate determinations of the radial magnification of the optic systems. Ultra-small gold nanoparticles are especially attractive in applications requiring delivery to crowded intracellular spaces in the cytosol and nucleus of cells. In collaboration with the Laboratory of Cellular Imaging and Macromolecular Biophysics of the NIBIB, we have used AUC and DLS to characterize the size-distribution of MBA and GSH stabilized ultrasmall gold particles in buffers with and without Fetal Bovine Serum (FBS). Using AUC, DLS and ITC, we continue to explore the size, shape and self association properties of various protein systems. Collaborative projects with NIAID led to exploratory AUC work on oligomeric states of wild type and mutant polypeptide constructs of NSP5, helped characterize individual proteins like DBL2x, PfCSA-pcm2 and their mixtures to answer questions regarding high affinity binding between these species and allowed us to continue our investigations into the study of the different oligormeric properties of several forms of serum amyloid A (SAA). In collaboration with NIDDK, we have studied the purity and self-association characterization of mutant RNA polymerase and investigated the crowding effect on riboswitch conformation of TMAO by measuring diffusion coefficients.

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National Institute of Biomedical Imaging and Bioengineering
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Jensen, Jaime L; Balbo, Andrea; Neau, David B et al. (2015) Mechanistic Implications of the Unique Structural Features and Dimerization of the Cytoplasmic Domain of the Pseudomonas Sigma Regulator, PupR. Biochemistry 54:5867-77
Zhao, Huaying; Balbo, Andrea; Metger, Howard et al. (2014) Improved measurement of the rotor temperature in analytical ultracentrifugation. Anal Biochem 451:69-75
May, Nathan A; Wang, Qiuhong; Balbo, Andrea et al. (2014) Human herpesvirus 7 U21 tetramerizes to associate with class I major histocompatibility complex molecules. J Virol 88:3298-308
Ghirlando, Rodolfo; Zhao, Huaying; Balbo, Andrea et al. (2014) Measurement of the temperature of the resting rotor in analytical ultracentrifugation. Anal Biochem 458:37-9
Zhao, Huaying; Berger, Anthony J; Brown, Patrick H et al. (2013) Analysis of high-affinity assembly for AMPA receptor amino-terminal domains. J Gen Physiol 141:747-9
Coussens, Nathan P; Hayashi, Ryo; Brown, Patrick H et al. (2013) Multipoint binding of the SLP-76 SH2 domain to ADAP is critical for oligomerization of SLP-76 signaling complexes in stimulated T cells. Mol Cell Biol 33:4140-51
Ghirlando, Rodolfo; Balbo, Andrea; Piszczek, Grzegorz et al. (2013) Improving the thermal, radial, and temporal accuracy of the analytical ultracentrifuge through external references. Anal Biochem 440:81-95
Sousa, Alioscka A; Morgan, Jeffrey T; Brown, Patrick H et al. (2012) Synthesis, characterization, and direct intracellular imaging of ultrasmall and uniform glutathione-coated gold nanoparticles. Small 8:2277-86
Zhao, Huaying; Berger, Anthony J; Brown, Patrick H et al. (2012) Analysis of high-affinity assembly for AMPA receptor amino-terminal domains. J Gen Physiol 139:371-88
Zhao, Huaying; Brown, Patrick H; Schuck, Peter (2011) On the distribution of protein refractive index increments. Biophys J 100:2309-17

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