RUI: Thermochemistry, Reaction Dynamics and Conformational Changes that Accompany the Collisional Activation of Peptide Ternary Complexes and Recombinant Tagged Proteins

With support from the Chemical Structure, Dynamics & Mechanisms-B Program of the Chemistry Division, Laurence Angel and Venugopalan Cheriyath of Texas A&M University - Commerce will develop new zinc- and nickel-binding small peptides using electrospray ionization - ion mobility - mass spectrometry techniques. Peptides characterized and optimized in this study may lead to the development of improved therapeutic protein purification. The primary educational goal is to engage, encourage, and retain students underrepresented in science; specifically, at the critical intersection of chemistry, biology and physics. Undergraduate students involved in the research will gain knowledge and experience of cutting edge instrumental, biochemical and theoretical techniques and share their findings at scientific meetings and in peer-reviewed journal publications. The study will determine the pH-dependent reactivity and metal ion affinity of alternative metal binding (AMB) peptides. Measurement of the pH-dependent reactivity will be done by electrospray ionization - ion mobility - mass spectrometry (ESI-IM-MS) techniques. The metal ion affinities will be determined from threshold collision-induced dissociation (TCID) analyses for determining the thermochemistry of the dissociation reactions of ternary complexes. TCID analyses requires realistic molecular parameters of the reactants and products and we will develop new procedures combining molecular dynamic simulations and PM7 for locating the lowest-energy conformers with collision cross sections that agree with those measured by ESI-IM-MS. The research will examine (i) thermochemistry of the dissociation reactions of [ambm+M(II)+ambn] and [ambm+M(II)+NTA] ternary complexes, where M = Ni or Zn and NTA = nitrilotriacetic acid; (ii) pH-dependent thermochemistry relating to different conformers of the ternary complexes; (iii) molecular dynamics simulations of the dissociation of the ternary complexes; (iv) selected AMBs as tags for the expression and purification of recombinant protein and (v) AMB-tagged protein conformational stability using collision-induced unfolding analyses. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.