| The research presented in this thesis examines problems in two different areas: the chemical origins of life and the chemistry of protein-surfactant interactions.;Chapter 1 describes the development of a method for resolving mixtures of inorganic polyphosphates, (Pi)n. The objective was to provide a tool for exploring the plausible prebiotic chemistry of (Pi)n, motivated by the hypothesis that (Pi)n was important to the chemical origins of life. The research developed a method that uses Capillary Gel Electrophoresis (CGE) and indirect UV-absorbance. The method was capable of resolving mixtures of (Pi)n with n ∼ 1--70 (including cyclo-P3), in CGE runs that were reproducible, quantitative, and convenient. A demonstration of the method revealed that cyclo-P3 is the major product when Pi is dehydrated in mixtures with urea heated at 135 °C. The method should be useful in three applications: (i) surveying reactions that synthesize or utilize (Pi)n; (ii) analyzing oligomeric or polymeric species other than (Pi) n that may have preceded RNA in the chemical origins of life (e.g., diesters of phosphate with glycerol); (iii) analyzing anionic biopolymers that lack UV-chromophores (e.g., teichoic acids).;Chapter 2 addresses the denaturation of proteins by the anionic surfactant dodecyl sulfate (DS-), a reaction exploited in the analysis of proteins in SDS-PAGE. This research examined a previously unexplored component to the interaction between DS- and proteins, the cation (C+), by analyzing proteins in solutions of Na+DS - or tetra-n-alkylammonium dodecyl sulfate (NR4+DS-, where R = Me, Et, Pr, Bu). Replacement of Na+ with increasingly hydrophobic NR 4+ resulted in a decrease in the rates of denaturation of bovine carbonic anhydrase II (BCA), by factors > 104 in some cases. The kinetics of denaturation, at concentrations of Na+ DS- and NR4+DS - below and above the critical micellar concentration (cmc), suggested a rate-limiting step that involves monomeric DS-, and not micelles of DS-. This research showed that the choice of cation is a potentially useful "knob-to-turn" for (i) investigating the mechanism of denaturation of proteins, and (ii) developing methods for the analysis and separation of mixtures of proteins.;Chapter 3 deals with the question of whether the hydrophobicity of fluorocarbon groups is distinguishable from that of hydrocarbon groups of similar surface area, in the context of the surfaces of proteins. The approach was to analyze derivatives of BCA with CF3CONH- and RHCONH- (R H = Me, Et, iPr) groups at the surface, prepared by the acylation of Lys-epsilon-NH3+ groups. Derivatives with CF 3CONH- denatured in solutions of SDS more rapidly than those with R HCONH- groups. The rates of denaturation, interpreted with a kinetic model inferring hydrophobic interactions between SDS and BCA, suggested that CF3CONH- groups are more hydrophobic than RHCONH- groups, and are therefore more hydrophobic than predicted on the basis of surface area alone. |
