The biological function of a protein is determined by its amino acid sequence, structure, and internal dynamics. In turn the prediction of a protein structure from its folding pathway involves the characterization of the dynamics of the polypeptide backbone. This study addresses how the internal dynamics of arborescent polypeptides are affected by increased crowding of the interior of these branched polymer molecules. Linear, comb-branched, and arborescent poly(L-glutamic acid) (PGA) samples were analyzed by 1H NMR spectroscopy to determine their chain conformation. The PGA chains of these constructs were shown to adopt α-helical and random coil conformations in N,N-dimethylformamide (DMF) and in dimethyl sulfoxide (DMSO), respectively. The hydrodynamic diameter (Dh) of the arborescent PGAs, determined using dynamic light scattering measurements, increased with increasing generation number and when the side-chains adopted random coil instead of α-helical conformations. The PGA samples were labelled with 1-pyrenemethylamine to determine how their structure affected the internal dynamics of the arborescent polymers in solution, from the analysis of their fluorescence spectra and decays. For each pyrene-labelled polymeric construct excimer formation increased with increasing pyrene content, and the efficiency of excimer formation increased with the generation number due to the increased density of the macromolecules. Comparison of the time-resolved fluorescence results acquired in DMF and in DMSO demonstrated that the helical conformation led to slower chain dynamics in DMF and that despite the higher viscosity of DMSO, the polypeptide side-chains were more mobile as a consequence of the random coil conformation of the linear PGA segments. These results suggest that the formation of structural motives inside a polypeptide slows down its internal dynamics.

Thesis (Ph. D. in Biological Science)--Vanderbilt University, Dec. 2007. / Title from title screen. Includes bibliographical references.

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Thesis (M.S.) -- Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 56-68).

Thesis (Ph.D. in Pharmacology) -- University of Colorado, 2005. / Typescript. Includes bibliographical references (leaves 145-170). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Thesis (Ph. D.)--University of Montana, 2007. / Title from title screen Description based on contents viewed Oct. 12, 2007. Includes bibliographical references (p. 151-177).

Probiotics are live microorganisms which when administered in adequate amounts confer one or more health benefits on the host. Different processing conditions, the acidic condition of the stomach and exposure to hydrolytic enzymes affect the viability and efficacy of probiotic organisms. This study investigated the protective effects of two biopolymers poly-gamma-glutamic acid (γ-PGA) and bacterial cellulose (BC) on probiotics during freeze drying and during exposure to simulated intestinal juices and bile salts. The antibacterial property of Bifidobacterium strains was also investigated against four pathogenic bacteria. γ-PGA, a naturally occurring biopolymer was produced by two bacteria (Bacillus subtilis ATCC 15245 and B. licheniformis ATCC 9945a) in GS and E media, γ-PGA yields of about 14.11g/l were achieved in shake flasks and molecular weight of up to 1620 k Da was recorded, γ-PGA production was scaled up in a fermenter with B. subtilis using GS medium. BC, an edible biopolymer was produced by Gluconacetobacter xylinus ATCC 23770 in HS medium and a modified HS (MHS) medium. A yield of about 1.37g/l was recorded and BC production with MHS medium was used for probiotic application. B. longum NCIMB 8809 B. breve NCIMB 8807 and B. animalis NCIMB 702716 showed the best antimicrobial properties against the investigated pathogens. Survival of Bifidobacterium strains was improved when protected with powdered BC (PBC) although γ-PGA offered better protection than PBC. Viability of B. longum NCIMB 8809, B. breve NCIMB 8807 and B. animalis NCIMB 702716 in simulated gastric juice (SGJ) and simulated intestinal juice with bile salts was improved when protected with 5% γ-PGA and 5% γ-PGA+PBC with a reduction of < 1 Log CFU/ml while a reduction of ≤2 Log CFU/ml was recorded in PBC protected cells. Protecting Bifidobacterium strains with γ-PGA, PBC or a novel γ-PGA + PBC combination is a promising method to deliver probiotic bacteria to the target site in order to confer their health benefits on the host.

Made available in DSpace on 2014-10-09T12:47:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:02Z (GMT). No. of bitstreams: 1 07976.pdf: 1699700 bytes, checksum: 1ecc44195023300aaef5127a99a940de (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2015-03-26T13:55:26Z (GMT). No. of bitstreams: 1 texto completo.pdf: 731897 bytes, checksum: 30a871869e66be99ff1dff6f3f4d5f2c (MD5) Previous issue date: 2014-05-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The experiment was conducted in a swine production commercial enterprise, using the semen of 29 boars ages between 10 months and 5 years, from a commercial line. The aim of the study was to evaluate the effect of adding 1% L-glutamine L-glutamic acid in the diet on boars fresh semen quality. The animals were divided into blocks in a completely randomized design, with two treatments, T1&#8722; standard farm diet (RP) and T2- standard farm diet + 1% L-glutamine L-glutamic acid (RP+LGln-LGlu). Diets were fed in mash form, formulated to meet the recommendations for boars. The seminal variables were: volume of semen, concentration, motility, force and morphology, and percentage of lives and dead sperm cells, and testes volume. The means for semen volume and sperm cells motility, were 255. 32±6.5 and 290.57±9.1; 87.72±0.2 and 89.89±0.01 respectively for T1 (RP) and T2 (RP±LGln-LGlu) treatments. The 1% L-glutamine L-glutamic acid add in the diet influenced semen volume and sperm cells motility (P 0.05). The mean for T1 (RP) and T2 (RP±LGln-LGlu) treatments were: sperm concentration (79.01±2.5 and 77.53±2.7), force (3.99±0.01 and 3.99±0.01), morphology (normal cells 90.1±0,4 and 88.59±0.6), live spermatozoa (92.43±1.8 and 93.23±2.5), dead sperm cells (7.56±0.2 and 6.84±0.2) and testicular volume (right: 668.06±32 and 739.27±31, left: 793.40±36 and 777.22±39) and were not affected by treatments (P>0.05). No interaction have been detected between treatment and age. The addition of 1% L-glutamine L-glutamic acid, on boars diet increased the fresh semen volume and sperm cells motility. / O experimento foi realizado em uma suinocultura de produção comercial, utilizando o ejaculado de 29 varrões de linhagem comercial com idades variando de 10 meses até 5 anos, com o objetivo de avaliar o efeito da adição de 1% de L-glutamina L-ácido glutâmico na ração sobre a qualidade do sêmen in natura. Os animais foram distribuídos em blocos em delineamento experimental inteiramente casualizado, sendo dois tratamentos: T1 &#8722; ração-padrão da granja (RP) e T2 ração-padrão da granja + 1% de L-glutamina L- ácido glutâmico (RP±LGln-LGlu). As rações foram fornecidas em forma farelada, formuladas para atender às recomendações para os varrões. As variáveis seminais analisadas foram: volume do ejaculado, concentração, motilidade, vigor e morfologia espermática, porcentagem de espermatozoides vivos e mortos e volume dos testículos. As médias registradas para o volume de sêmen e a motilidade foram 255,32±6,5 e 290,57±9,1; 87,72±0,2; e 89,89±0,01, respectivamente nos tratamentos T1 (RP) e T2 (RP±LGln-LGlu). A inclusão de 1% de L-glutamina L-ácido glutâmico na ração afetou (P 0,05) o volume do ejaculado e a motilidade espermática. Em valores absolutos, proporcionou melhoras de 12,3% no volume e de 2,47% na motilidade, em comparação com a ração-padrão da granja. Os valores médios no T1 (RP) e T2 (RP±LGln-LGlu) para concentração (79,01±2,5 e 77,53±2,7), vigor (3,99±0,01 e 3,99±0,01), morfologia (células normais 90,1±0,4 e 88,59±0,6), espermatozoides vivos (92,43±1,8 e 93,23±2,5), espermatozoides mortos (7,56±0,2 e 6,84±0,2) e volume dos testículos (direito: 668,06±32 e 739,27±31; esquerdo: 793,40±36 e 777,22±39, respectivamente no T1 e T2) não apresentaram diferença em relação à RP e RP±Gna-Glu (P>0,05). Não houve interação entre o tratamento e a idade dos animais. A adição de 1% de L-glutamina L-ácido glutâmico na ração de varrões aumentou o volume do ejaculado e a motilidade das células espermáticas do sêmen in natura.