http://hdl.handle.net/1721.1/7792 http://hdl.handle.net/1721.1/17743 Fluorescence-based detection methodologies for nitric oxide using transition metal scaffolds Hilderbrand, Scott A. (Scott Alan), 1976- Chapter 1. Fluorescence-Based Detection Methodologies for Nitric Oxide: A Review. Chapter 2. Cobalt Chemistry with Mixed Aminotroponimine Salicylaldimine Ligands: Synthesis, Characterization, and Nitric Oxide Reactivity. Chapter 3. Carboxylate-Bridged Dimetallic Complexes as Potential Nitric Oxide Sensors. Chapter 4. Dirhodium Tetracarboxylate Scaffolds as Reversible Fluorescence- Based Nitric Oxide Sensors. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004. MIT Institute Archives copy has p. 191-192 bound between p. 188 and p. 189. Vita. Includes bibliographical references. http://hdl.handle.net/1721.1/12465 A synthetic attack on the oestrone problem Woodward, R. B. (Robert Burns), 1917-1979 Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1937. Vita. Includes bibliographical references (leaves [53]-[54]). http://hdl.handle.net/1721.1/41773 Intramolecular Heck couplings of unactivated alkyl electrophiles : synthetic and mechanistic studies Firmansjah, Luke A method for the palladium-catalyzed intramolecular Heck coupling of unactivated alkyl bromides and chlorides is described. The optimal catalyst system was composed of Pd2(MeO-dba)3 as the metal source and N-heterocyclic carbene SIMes as the ligand, and the influence of both parameters is discussed. Reaction of a diastereomerically pure, deuterium-labeled substrate gave only one diastereomer of product, suggesting that the reaction does not proceed through radical pathway, in contrast to processes currently described in the literature. Mechanistic studies involved the synthesis of novel complex Pd(SIMes)2 and a number of its oxidative addition adducts, which were thought to resemble intermediates along a postulated catalytic cycle. However, the alkylpalladium species thus obtained, which were characterized by X-ray crystallography and which bear freely accessible 3 hydrogen atoms, are air and moisture-stable compounds that display no tendency for P-hydride elimination, even upon heating. These complexes are therefore not thought to be part of the catalytic cycle. It was further demonstrated that while Pd(SIMes)2 is not itself catalytically competent in the reaction, it may serve as a catalyst precursor. Evidence is provided to suggest that the true active catalyst is composed of a mixed ligand complex involving both SIMes and dba ... Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, September 2007. "August 2007." Includes bibliographical references. http://hdl.handle.net/1721.1/41772 Energetics of substrate unfolding by ClpA James, Melva Tonisha Caseinolytic protease A (ClpA), a member of the Hsp 100 family of heat shock proteins, is the regulatory subunit of the E. coli protease ClpAP. As such, it recognizes proteins targeted for degradation by the cell and uses the energy of ATP hydrolysis to unfold substrates and translocate them to ClpP for proteolysis. ClpA's in vivo contribution to cellular maintenance is small, but it serves as an ideal model for energy-dependent molecular machines. The goal of this work is to describe the energetics of ClpA's interactions with both soluble and membrane-bound protein substrates. Green fluorescent protein modified with an 11-amino acid tag that facilitates ClpA recognition (GFP-ssrA) is used as a model soluble substrate, and ssrA-modified acetylcholine receptor (AChR-ssrA) is used as a model membrane-bound substrate.The structural and spectroscopic properties of GFP have been previously described. Here, in order to determine the minimum amount of energy needed to unfold this protein, we present two estimates of the free energy of unfolding (AGunfolding) for GFP-ssrA derived from thermal and chemical denaturation data. We find that GFP-ssrA is highly kinetically stable (tequil > 600 hrs.) and that AGunfolding = 0-2 kcal/mol. In addition, we show that ClpA retains its enzymatic activity under conditions which support single-molecule patch-clamp electrophysiology. These observations made it possible to carry out pilot studies for a novel electrophysiological unfoldase assay. ClpA may be able to actively extract protein substrates from the lipid bilayer. We are currently testing this hypothesis, and we are exploring ways to observe the process of substrate removal in real-time. The proposed electrophysiological unfoldase assay, once optimized, could be used to elucidate the mechanistic details of ClpA's interaction with membrane-bound substrates. (cont.) We are specifically interested in determining the timescale of substrate removal and determining whether or not the substrate removal process occurs in one high-energy step or several low-energy steps. Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007. Vita. Includes bibliographical references (leaves 52-56).