No description available.

No description available.

No description available.

Thèse de doctorat : Chimie organique : Strasbourg 1 : 2007. / Titre provenant de l'écran-titre. Notes bibliogr.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Neal Zondlo, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

Investigation on a series of hydrogen-bonded networks constructed with N-heteroaryl acids is described in Section 3.4. In this section, we focused on the connection modes within the heteroaryl dimer. The study of co-crystals and inclusion compounds based on 2-thiobarbituric acid (TBA) or trithiocyanuric acid (TCA) indicated that the dimer of TBA is present in all three crystals in the forms of ribbon, tetramer or separated dimer. In the case of 5-nitrobarbiturate, its dimer occurs in two ammonium salts and in three of its four thiourea complexes, but is absent in all three urea complexes. / Self-assembly of two-dimensional hydrogen-bonded honeycomb grids exhibiting the rosette motif has been conducted with the guanidinium cation and various anions as the building blocks, tetraalkylammonium ions of suitable bulk being employed as interlayer templates. It is noteworthy that the rosette layer constructed from three different trigonal-planar molecular components has been achieved. In addition, deviating from conventional topological design, the generation of new rosette layers, albeit highly distorted, has also been accomplished with 1,2-dithiosquarate and the dianionic form of 1,1'-biphenyl-2,2',6,6'-tetracarboxylate that do not conform to C3-symmetry. Although threefold molecular symmetry is regarded as a sacrosanct requirement for molecular building blocks in the construction of hydrogen-bonded rosette motif, this study shows that rosette motifs can be generated even if one of the building blocks does not have inherent threefold symmetry. / Study of compounds containing the deprotonated forms of Kemp's triacid (H3KTA) has revealed the chair or twist-boat conformation in six crystal structures. X-ray structural analysis showed that [C(NH2) 3+] · [C6H6(CH3) 3(COOH)2(COO-)] (2.2.2) exhibits a corrugated layer structure which mimics the rosette motif constructed from the guanidinium ion and the hydrogen carbonate dimer. The tricarboxylate form of Kemp's triacid KTA3- in 3[C(NH2) 3+] · [C6H6(CH3) 3(COO-)3] (2.2.4) registers a record number of eighteen acceptor hydrogen bonds involving the convergent N--H donor sites from nine guanidinium ions. The crystal structure of 3[(C2H5)4N+] · 20[C(NH 2)3+] · 11[C6H6(CH 3)3(COOH) (COO-)2] · [C6H6(CH3)3(COOH)2(COO -)]·17H2O (2.2.3) features a hydrogen-bonded aggregate with a centrosymmetric pseudo-octahedral arrangement of H2KTA- anions surrounding an inner core composed of eight guanidinium ions. The unusual twist-boat conformation of KTA3- is found in [(CH3)4N +] · 2[C(NH2)3+] · [C6H6(CH3)3(COO- )3] · 2H2O (2.2.6), which is stabilized by the co-existence of guanidinium and tetramethylammonium cations. / Systematic investigation on hydrogen-bonded supramolecular assembly using aromatic carboxylic acids bearing linear or bent skeletons with urea/guanidinium resulted in the formation of mainly R228 and R126 synthon motifs. In addition, isostructures were also constructed by varying the length of the linker between two carboxylate groups, as in naphthalene-2,6-dicarboxylate (2.3.2) and biphenyl dicarboxylate (2.3.3). / This thesis reports a systematic investigation on the generation of new inclusion compounds by the combined use of urea/thiourea, guanidinium ion and various organic anions as building blocks of hydrogen-bonded host lattices and selected quaternary ammonium ion as the enclosed guests. / Various acids bearing specific functional groups have been explored as structure building components, including boric acid, Kemp's triacid, heterocyclic (thio)urea derivatives, aryl and N-heteroaryl carboxylic acids and (dithio)squaric acid. All the co-crystals and inclusion compounds built of molecular components in the afore-mentioned categories have been characterized by single-crystal X-ray analysis. As a result, the complexes exhibit a rich variety of inclusion topologies, such as networks containing isolated cages, open channels, intersecting tunnels, double-layer systems, and sandwich-like as well as wave-like layer structures. / Han, Jie. / Adviser: Thomas C. W. Mak. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0337. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 204-218). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Staphylococcus aureus protease V8 (SPV8), also known as Endoproteinase Glu-C (EC 3.4.21.19), is an enzyme isolated from the bacteria Staphylococcus aureus. This unusual enzyme has been found to cleave specifically at glutamyl and aspartyl peptide bonds and has been used as a tool in the preparation of protein substrates for amino acid sequence analysis. SPV8 has been reported to show some stability toward various denaturants (Drapeau, G.R. (1977) Methods in Enzymology_, 47:189-191). In order to more adequately assess the denaturant stability of SPV8, the effect of guanidine hydrochloride (HC1), a common protein denaturant, on the proteolytic action of SPV8 was studied. The extent of cleavage of the glutamyl peptide bond in adrenocorticotropic hormone 1-10 (ACTH 1-10) was found to decrease with increasing concentrations of guanidine HC1.At 22°C in the presence of 3.0 M guanidine HCl, only 25% of SPV8's proteolytic activity was retained. In the presence of 4.0, 5.0, or 6.0 M guanidine HC1, virtually all proteolytic activity toward the glutamyl bond of ACTH 1-10 was lost, presumably due to the inactivation of the protease by denaturation or increased autolysis mediated by the guanidine HC1. At temperatures above 22°C, SPV8 was more susceptible to inactivation by guanidine HC1. Thus SPV8 appears to retain some proteolytic activity in the presence of guanidine HC1, but only at concentrations less than 4.0 M. There was no difference in the proteolytic activity of SPV8 toward the glutamyl peptide bond of ACTH 1-10 when incubation was carried out in ammonium bicarbonate buffer (pH 7.80), phosphate buffer (pH 7.80), or Tris-HC1 buffer (pH 7.80). The presence of 1 mM calcium chloride in the 3.0 M guanidine HC1/phosphate buffer solution enhanced the enzymatic action of SPV8. The presence of 1 mM calcium chloride in Tris-HC1 buffer (pH 7.80) does not effect the proteolytic activity of SPV8 at 22°C. However, there was slight reduction in SPV8's enzymatic action toward ACTH 1-10 when the 1 mM calcium chloride was present in the 3.0 M guanidine HC1/ammonium bicarbonate buffer (pH 7.80) solution. / Department of Chemistry

Orientador: Ulf Friedrich Schuchardt / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T15:30:30Z (GMT). No. of bitstreams: 1 Silva_CleberLuisMaiada_M.pdf: 678051 bytes, checksum: 10521f93d061aa54afb62bb295f4e845 (MD5) Previous issue date: 2005 / Mestrado / Quimica Inorganica / Mestre em Química