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Transparent window vibrational probes for the characterization of proteins with high structural and temporal resolution

R. Adhikary, J. Zimmermann, F.E. Romesberg, Chem. Rev. (2017) 117:1927–1969.
pubpic2017adhikaryWe review the strengths and weaknesses of the different transparent window vibrational probes, methods by which they may be site-specifically incorporated into peptides and proteins, and the physicochemical properties they may be used to study. These topics are put into context through four case studies focused on KSI, SH3, DHFR, and cyt c.

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Adaptive mutations alter antibody structure and dynamics during affinity maturation

R. Adhikary, W. Yu, M. Oda, T. Chen, R. Walker, R. Stanfield, I. Wilson, J. Zimmermann, F.E. Romesberg, Biochemistry (2015) 54:2085–2093.
pubpic2015adhikaryIn this work, three affinity matured anti-MPTS antibodies (Abs) are characterized via X-ray and spectroscopic studies and the results are discussed in terms of the elasticity, anelasticity, and plasticity of the complexes. We find that the level of plasticity of the Ab-MPTS complexes is correlated with specificity, suggesting that the optimization of protein dynamics may have contributed to affinity maturation.

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Evidence of an unusual N-H—N hydrogen bond in proteins

R. Adhikary, J. Zimmermann, J. Liu, R. Forrest, T. Janicki, P. Dawson, S. Corcelli, F.E. Romesberg, J. Am. Chem. Soc. (2014) 136:13474-13477.
pubpic2014adhikaryWe characterize the IR stretching frequencies of deuterated variants of proline and four proline residues of an Src homology 3 domain protein. CD stretching frequencies are shifted to lower energies due to hyperconjugation with Ni electron density, and along with DFT calculations, the data reveal that the Ni+1-H–Ni interactions constitute H-bonds that may play an important role in protein folding, structure, and function.

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IR probes of protein microenvironments: utility and potential for perturbation

R. Adhikary, J. Zimmermann, P.E. Dawson, F.E. Romesberg, ChemPhysChem (2014) 15:849-853.
pubpic2014adhikaryWe use IR spectroscopy to characterize nSH3 variants labeled with CN or N3 at five different positions. Like carbon-deuterium (C-D) bonds, CN and N3 can provide information about their surrounding protein environment, but unlike C-D, they tend to be perturbative and thus should be used with caution.

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Experimental characterization of electrostatic and conformational heterogeneity in an SH3 domain

R. Adhikary, J. Zimmermann, J. Liu, P.E. Dawson, F.E. Romesberg, J. Phys. Chem. B, 117:13082-13089.
pubpic2013adhikaryWe use the IR absorptions of carbon-deuterium bonds site-selectively incorporated throughout the N-terminal SH3 domain from the murine adapter protein CrkII to characterize its different microenvironments with high spatial and temporal resolution.

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Protein dynamics and the diversity of the antibody response

R. Adhikary, W. Yu, M. Oda, J. Zimmermann, F.E. Romesberg, J. Biol. Chem. (2012) 287:27139-27147.
pubpic2012adhikaryWe report the sequence, thermodynamic, and time-resolved spectroscopic characterization of a panel of eight antibodies (Abs) elicited to a chromophoric antigen (MPTS). Three of the Abs arose from unique germline Abs, while the remaining five comprise two sets of siblings that arose by somatic mutation of a common precursor. By characterizing both flexibility and conformational heterogeneity, we show that point mutations are capable of fixing significant differences in protein dynamics.