Spelling suggestions: "subject:"5ubstrate"" "subject:"asubstrate""
11 |
Towards Fluorinated Substrate Analogs and N-Acylated 2-Aminopyrimidine Inhibitors of LipoxygenasesHaycock, Meghan Lynn January 2014 (has links)
Cyclooxygenase (COX) and lipoxygenase (LOX) catalyze the rate-determining step in the production of arachidonic acid- derived signaling molecules (eicosanoids) within the body. COX has been extensively investigated, which has enabled the design of non-steroidal inflammatory drugs (NSAIDs) such as aspirin, acetaminophen (ApAP) and ibuprofen. However, there are still fundamental questions surrounding the LOX family of enzymes, which has limited the development of isoform specific inhibitors. The structural basis and regio- and stereoselectivity of the LOX isoforms are not known. Herein, we describe two strategies to develop isoform-specific inhibitors of lipoxygenase.
Efforts were focused on the synthesis of unnatural lipid derivatives, in which the methylene hydrogen atoms on the substrate were replaced with a moiety lacking a labile hydrogen atom, such as fluorine. This would allow the LOX enzyme to remain in an active form, while preventing enzyme turnover. This preliminary work will enable the assessment of their activity as inhibitors and attempts at their co-crystallization might provide the first insight into the binding mode of these fatty acid substrates.
The preparation of a small library of acylated 2-aminopyrimidines and their efficacy as inhibitors of soybean lipoxygenase-1 was explored. Preliminary studies suggest the mode of action occurs through a bi-dentate coordination of the ferric iron atom. Modifications of the acylated 2-aminopyrimidines to make it more substrate-like and to increase its lipophilicity, yielded inhibitors with low micromolar IC50 values. With further optimization, acyl 2-aminopyrimidines could serve as a useful platform for the discovery of safe and efficient isoform specific inhibitors.
|
12 |
Factors Affecting Pigment Production in Mycobacterium rhodocrousChamberlain, Charlene 06 1900 (has links)
This study was undertaken in order to isolate and identify the pigment, if possible, and to determine the effect of substrate, substrate concentration, light exposure, and pH on pigment production in this organism.
|
13 |
Studies on the substrate specificity of aromatic-1-amino acid decarboxylaseBuckpitt, Alan Ridler January 1973 (has links)
This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).
|
14 |
Elucidation of Enzyme-Substrate Selectivity Using a Quick Quantitative Screening ProtocolSomers, Neil A. January 1999 (has links)
No description available.
|
15 |
Contribució a l'estudi de l'acoblament per substrat en circuits integrats mixtesAragonès Cervera, Xavier 16 December 1997 (has links)
L'acoblament de soroll a través del substrat en circuits integrats mixtos és un important problema que sovint limita les prestacions de la circuiteria analògica. Les característiques d'aquest tipus d'acoblament i els factors que en determinen la importància no són ben compresos, així que calen criteris per tal de triar les millor accions per a resoldre el problema. En els darrers anys s'han proposat algunes tècniques per reduir el soroll de substrat, tot i que no hi ha una idea clara de l'abast de la seva validesa, i de les condicions que calen per a la seva eficàcia. La majoria de l'esforç de recerca que s'ha dedicat a aquest tema s'ha centrat en el desenvolupament de models, que permetin la incorporació del substrat en les eines CAD que s'utilitzen en les fases de simulació dels dissenys. Per tant, aquests resultats de recerca no contribueixen a la comprensió dels aspectes rellevants de l'acoblament.En aquesta tesi doctoral s'ha realitzat un estudi analític i experimental que ha permès determinar les característiques tecnolòiques i de disseny que faciliten l'acoblament vers la circuiteria analògica. S'ha partit d'una caracterització de l'acoblament mitjançant un simulador de dispositius, on s'ha pogut comprovar la importància d'aspectes com el tipus de substrat, la velocitat de commutació dels dispositius, les seves dimensions, o el punt de polarització. La caracterització s'ha realitzat tant per tecnologies CMOS com BiCMOS, i ha estat completada amb mesures sobre estructures de test. Posteriorment s'ha portat a terme un anàlisi de la propagació del soroll en el substrat, amb el que s'han esbrinat les característiques tecnològiques i de polartizació que determinen l'atenuació del soroll. L'anàlisis'ha realizat suposant condicions de polarització ideals, i ha permès determinar el potencial d'algunes mesures per a la minimització de l'acoblament. A continuació s'ha fet una revisió de les diverses tècniques de modelació del substrat, i utilitzant algun dels models s'han pogut realitzar simulacions circuitals per a estudiar l'acoblament en circuits de dimensions realistes, tenint en compte factors com els elements paràsits dels terminals de l'encapsulat, la influència dels pads, o l'estratègia de polarització. Aquest estudi s'ha complementat amb el disseny d'un circuit mixte de test sobre el que s'han fet mesures per a verificar els resultats obtinguts, i corroborar els mecanismes que determinen l'acoblament. La tesi s'ha completat amb una revisió de l'eficàcia d'algunes tècniques específiques per a la reducció del soroll, i amb un estudi de l'evolució en tecnologies futures tant del soroll de commutació a les línies d'alimentació, com del soroll acoblat a través del substrat. / El acoplo de perturbaciones a través del sustrato de silicio en circuitos integrados mixtos representa un importante problema que a menudo limita las prestaciones de la circuiteria analógica. Hay una cierta incomprensión de las características del acoplo i de los factotres que que determinan su importancia, de forma que faltan criterios para implementar técnicas que reduzcan el problema. En los últimos años se han propuesto diversas técnicas para la reducción del ruido de sustrato, aunque no estan claros su rango de validez y las condiciones que se deben cumplir para su eficacia. La mayor parte del esfuerzo investigador realizado en este campo se ha centrado en el desarrollo de modelos que faciliten la incorporación del sustrato a las herramientas CAD utilizadas en la fase de simulación de un circuito. Por tanto, esta investigación no ofrece aportaciones en la comprensión de los aspectos relevantes del fenómeno.En esta tesis doctoral se ha realilzado un estudio analítico y experimental que ha permitido determinar las características tecnológicas y de diseño que facilitan el acoplo sobre la circuitería analógica. Se ha partido de una caracterización del acoplamiento mediante un simulador de dispositivos, donde se ha podido comprovar la importancia de aspectos como el tipo de sustrato, la velocidad de conmutación de los dispositivos, sus dimensiones, o el punto de polarización. La caracterización se ha realizado tanto para estructuras CMOS como BiCMOS, y ha sido completada con medidas sobre estructuras de test. Posteriomente se ha llevado a cabo un análisis de la propagación del ruido en el sustrato, con el que se han determinado las características tecnológicas y de polarización que determinan la atenuación del ruido. El análisis se ha realizado suponiendo condiciones de polarización ideales, y ha permitido determinar el potencial de algunas medidas para la minimización del acoplo. A continuación se ha realizado una revisión de las diversas técnicas de modelación del sustrato, y utilizando alguno de los modelos se han podido realizar simulaciones circuitales para estudiar el acoplo en circuitos de dimensiones realistas, teniendo en cuenta factores como los elementos parásitos de los terminales del encapsulado, la influencia de los pads, o la estrategia de polarización. Este estudio se ha complementado con el diseño de un circuito mixto de test sobre el que se han hecho medidas para verificar los resultados obtenidos, y corroborar los mecanismos que determinan el acoplo. La tesi se ha completado con una revisión de la eficacia de algunas técnicas específicas para la reducción del ruido, y con un estudio de la evolución en tecnologías futuras tanto del ruido de conmutación a través de las líneas de alimentación, como del ruido acoplado a través del sustrato. / Noise coupling through common silicon substrate in mixed-signal circuits is an important problem that often limits the performance of the analog circuitry. The characteristics of this type of coupling and the factors determining its importance are not well understood, so criteria to choose the best actions to solve the problem are needed. Several techniques to reduce substrate noise have been proposed in the last years, although there is no clear idea about their range of validity, and the conditions required for their efficacy. Most of the research effort done in this field has been centered on the development of models, in order to allow the incorporation of substrate in the CAD tools used in simulation design stages. Thus, these research results do not contribute to the understanding of the relevant aspects of coupling.In this thesis an analytic and experimental study has been done, which has allowed determining the technological and design characteristics relevant in the coupling. The study has started with a characterisation of coupling using a device simulator, which has allowed determining the importance of aspects such as substrate type, device switching speed, device dimensions, or their biasing. Characterisation has been done both for CMOS and BiCMOS technologies, and it has been completed with measurements on test structures. Next an analysis of noise propagation through the substrate has been carried out, which has allowed to find out the biasing and technological characteristics that determine noise attenuation. The analysis has been done assuming ideal biasing conditions, and the potentiality of some noise minimisation measures could be determined. Next a review of the different substrate modelling techniques has been done, and some of the models have been used to perform circuit simulations to study coupling in circuits of some complexity, taking into account factors such as package pins parasitics, the influence of the ring of pads, or the biasing strategy. This study has been complemented with the design and measurements of a mixed-signal test circuit, which allowed verification of the results previously obtained, and the coupling mechanism. Finally the thesis is completed with a review of the efficacy of noise-reducing specific techniques, and with the study of the trends of switching noise on power supply lines and substrate for near future technologies.
|
16 |
REDUCED APERTURE MICROSTRIP ANTENNAS FOR AIRBORNE VEHICLESKujiraoka, Scott R., De Vries, James M. 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The available space for the mounting of antennas on missiles and airborne targets is very
limited. The vehicle integrator is constantly striving for smaller antenna apertures while
requiring increased performance. Microstrip antennas with moderate dielectric loading
have been successfully utilized in the past to meet these requirements. With the advent of
high dielectric substrate materials, the designer now has the option of further reducing the
size of the antenna while preserving the most desirable performance attributes. An example
of the size reduction achievable with the new substrate materials is presented along with
performance characteristics.
|
17 |
An investigation into the molecular basis of substrate specificity in lactate dehydrogenaseHart, K. W. January 1989 (has links)
No description available.
|
18 |
Interaction between oestradiol and the IGF-I signal transduction pathway in breast cancer cellsMolloy, Claire Ann January 1999 (has links)
No description available.
|
19 |
Analysis of model environmental pollutants : preliminary microcalorimetric studiesCha, Jimin January 1996 (has links)
No description available.
|
20 |
Microbial biopolymers from whey : production and applicationsDlamini, Abednego Mfanufikile, University of Western Sydney, Hawkesbury, Faculty of Science, Technology and Agriculture, School of Applied and Environmental Sciences January 1997 (has links)
The main aim of this research was to utilise whey as a fermentation substrate for the production of microbial biopolymers.Of the three commercial biopolymer producers tested for biopolymer production in whey, only Pseudodomonas elodea produced significant apparent viscosities of up to 470cP at 2 s-1 on enriched whey broths. In these broths lactose utilisation was poor (14% w/v). A strain of P. elodea that had improved lactose utilising capacity was selected after six serial transfers on whey and lactose rich broths. After screening more than 60 bacterial isolates, a strain of Klebsiella oxytoca that initially produced a broth apparent viscosity of 36 cP at 12 s-1 in whey was isolated from raw milk. Biopolymer production was optimised in the K. oxytoca isolate.Concentrations of over 16 g/1 and broth apparent viscosities greater than 20,000 cP at 0.6 s-1 were obtained after optimisation. The biopolymer produced by the K. oxytoca isolate was shown to contain rhamnose, glucose and cellobiose, a composition not comparable to any reported polysaccharide. Polymer application studies indicated that it had potential to be used as a thickener, stabiliser, and binder. / Doctor of Philosophy (PhD)
|
Page generated in 0.0595 seconds