Thesis (Ph.D.)--University of Iowa, 2006. / Supervisor: Raymond J. Hohl. Includes bibliographical references (leaves 114-129).

No description available.

The vascular system transports components essential to the survival of the individual and acts as a barrier to substances that may injure the organism. Atherosclerosis is a dynamic, lesion producing disease of the arterial system that compromises the functioning of the organ by occlusive and thrombogenic processes. This investigation was undertaken to elucidate some of the normal biochemical processes related to the development of atherosclerosis. A significant part of the investigation was directed toward developing and combining methods and protocols to obtain the data in a concerted manner. A postmitochondnal supernatant of bovine aorta, using mevalonate-2-�����C as the substrate, was employed in the investigation. Methods included paper, thin layer, and silica gel chromatography; gel filtration, high performance liquid chromatography (HPLC), and mass spectrometry. This current research demonstrated direct incorporation of mevalonate-2- �����C into the trans-methyiglutaconic shunt intermediates. The aorta also contains alcohol dehydrogenase activity, which converts dimethylallyl alcohol and isopentenol to dimethylacrylic acid, a constituent of the trans-methylgiutaconate Small, radioactive peptides, named Nketewa as a group, were biosynthesized using mevalonate-2-�����C as the substrate. They were shown to pass through a 1000 D membrane. Acid hydrolysis and dabsyl-HPLC analysis defined the composition of the Nketewa peptides. One such peptide, Nketewa 1, had a molecular weight of 1038 and a sequence of his-gly-val-cys-phe-ala-ser-met (HGVCFASM), with a farnesyl group linked via thioether linkage to the cysteine residue. Methods were developed for the concerted investigation of the trans-methylglutaconate shunt, the isolation of mevalonate-2-�����C labeled peptides, and characteristics of neutral and acidic metabolites of mevalonate. The question as to whether or not mevalonate was the direct precursor was answered in the affirmative. These results contribute to the understanding of the biochemistry of the vessel wall and the associated atherogenic processes. Mevalonate-derived volatile and acidic compounds may represent an alternate metabolic pathway. The prenylated Nicetewa peptide may be, as are other prenylated peptides, participants in the intracellular signaling process, release of cytokines, expansion of extracellular matrix, and calcium release. / Graduation date: 2001

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 203-238).

published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

Orientador: Delia Rodriguez-Amaya / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T01:25:42Z (GMT). No. of bitstreams: 1 Sentanin_MichelleAndriati_D.pdf: 945275 bytes, checksum: 8006d9bfad9ddd336494867a2761a66f (MD5) Previous issue date: 2011 / Resumo: Os carotenóides são corantes naturais, alguns dos quais são precursores de vitamina A. Desde a década passada, tem sido atribuído a estes compostos um importante papel na diminuição do risco de várias doenças degenerativas. Com estas funções vitais, a procura por fontes intensificou-se mundialmente. A produção biotecnológica de carotenóides específicos, utilizando bactérias, fungos e leveduras, vem despertando crescente interesse. O presente trabalho teve como objetivos otimizar a extração dos carotenóides de Rhodotorula glutinis, estimular a produção de carotenóides pela adição de ácido mevalônico, substituir o meio de cultivo por substrato de baixo custo e avaliar a estabilidade e degradação de toruleno. O capítulo 1 apresenta uma revisão bibliográfica sobre a biossíntese de carotenóides e a produção biotecnológica desses pigmentos nos últimos dez anos, destacando a produção por bactérias, algas e fungos. O segundo capítulo visa otimizar a extração dos carotenóides da levedura Rhodotorula glutinis e avaliar o efeito de diferentes concentrações de ácido mevalônico na produção de carotenóides. Por ser um precursor chave no caminho biossintético dos carotenóides em leveduras, este composto influenciou de modo significativo a produção dos pigmentos. Apesar da quantidade de biomassa não ter sido afetada, a produção de carotenóides totais aumentou em até 114% e o rendimento de toruleno e de b-caroteno aumentou 157% e 168%, respectivamente. O Capítulo 3 tem o intuito de baixar o custo de produção de carotenóides pela levedura em estudo, através da substituição do meio de cultura usual YM por um residuo da industria da mandioca, a manipueira, substrato rico em nutrientes. Para otimizar a producao dos pigmentos, realizou-se um planejamento fatorial completo de quatro variaveis, a saber pH, temperatura, agitacao e volume de inoculo. A condicao que melhor favoreceu o rendimento de carotenoides foi 26°C, 250 rpm de agitacao, pH 7,0 e 10% de volume de inoculo. Nessa condicao, a producao de carotenoides totais foi de 2068 ?g/L de meio de cultura. O tradicional meio YM proporcionou a producao de apenas 899 ?g/L de meio de cultura de carotenoides totais. O quarto capitulo tem por objetivo avaliar a estabilidade do carotenoide toruleno produzido por Rhodotorula, em comparacao com os carotenoides bem conhecidos licopeno e ?-caroteno. Para isso, foram montados sistemas modelos de baixa umidade, utilizando como matriz celulose microcristalina, que ficaram expostos durante 15 dias a luz ou ao abrigo da mesma. O carotenoide que mais sofreu degradacao foi o licopeno, seguido de ?-caroteno e toruleno. O Capitulo 5 visa investigar a degradacao oxidativa do toruleno e os compostos volateis produzidos durante esse processo. Para atingir esse objetivo, foram montados sistemas modelo de baixa umidade, com matriz de celulose microcristalina, em frascos de vidro, com injecao de fluxo de oxigenio. Houve a formacao de diversos compostos de degradacao, dos quais os que mais se destacaram, quantitativamente, foram metacroleina, prenal, 2,6- dimetil-hepta-2,4-dieno, 6-metil-hept-5-en-2-ona, 2-etil-hexanol, 2-etenil- 1,3,3-trimetil-ciclohexeno e 3,3-dimetil-acetaldeido-ciclohexilideno / Abstract: Carotenoids are natural colorants, some of which are precursors of vitamin A. Since the past decade, an important role in reducing the risk of various degenerative diseases was attributed to these compounds. With these vital functions, the search for sources has intensified worldwide. The biotechnological production of specific carotenoids, using bacteria, fungi and yeasts, have attracted increasing interest. This study had the objective of optimizing the extraction of carotenoids from Rhodotorula glutinis, stimulating the production of carotenoids with mevalonic acid, substituting the medium with low-cost substrate and evaluating the stability and degradation of torulene. Chapter 1 presents a review of the biosynthesis of carotenoids and biotechnological production of these pigments in the last ten years, highlighting the production by bacteria, algae and fungi. The second chapter aims to optimize the extraction of carotenoids from the yeast Rhodotorula glutinis and assessing the effect of different concentrations of mevalonic acid on the production of carotenoids. Being a key precursor in the biosynthetic pathway of carotenoids in yeasts, it significantly influenced the production of pigments. Although the amount of biomass was not affected, the production of total carotenoid increased by 114% and the yield of torulene and ?-carotene increased by 157% and 168%, respectively. Chapter 3 is intended to lower the cost of production of carotenoids by the yeast under investigation, by replacing the usual culture medium YM with a sub-product of the cassava industry, the nutrient-rich substrate manipueira. To optimize the production of pigments, a full factorial design was used with four variables: pH, temperature, agitation and inoculum volume. The condition that favored yield of carotenoids was: 26°C, 250 rpm agitation, pH 7.0 and 10% volume of inoculum. In this condition, the production of carotenoids was 2068 mg/L of culture medium. The traditional YM provided the production of only 899 mg/L of culture medium of carotenoids. The fourth chapter aims to evaluate the stability of torulene produced by Rhodotorula, compared with well-known carotenoids, lycopene and b-carotene. For this purpose, model systems of low moisture were mounted, using microcrystalline cellulose as the matrix, which were kept in the dark or exposed to light for 15 days. The carotenoid that suffered the most degradation was lycopene, followed by b-carotene and torulene. Chapter 5 investigates the oxidative degradation of torulene and the volatile compounds produced during this process. To achieve this goal, model systems of low moisture were mounted, with microcrystalline cellulose matrix, in glass bottle, with injection of oxygen flow. Several degradation compounds were formed, of which the following compounds stood out quantitatively: methacrolein, prenal, 2,6-dimethyl-hepta-2,4-diene, 6-methyl-hept-5-en-2- one, 2-ethylhexanol, 2-ethenyl-1,3,3-trimethyl-cyclohexene and 3,3-dimethylciclohexilideno acetaldehyde / Doutorado / Ciência de Alimentos / Doutor em Ciência de Alimentos