http://hdl.handle.net/10362/3397 2013-06-20T05:44:18Z 2013-06-20T05:44:18Z Brito, José A. http://hdl.handle.net/10362/6856 2012-01-20T17:47:04Z 2011-09-01T00:00:00Z

Title: Crystallographic studies on two hyperthermophilic enzymes Authors: Brito, José A. Abstract: While Aristotle cautioned “everything in moderation”, the Romans, known for their eccentricities, coined the word “extremus”, the superlative of exter, “being on the outside”. By the fifteenth century “extreme” had arrived to English, via Middle French. At the beginning of the 21st century, we know that Earth contains environmental extremes unimaginable to our ancestors of the 19th century. Even more unimaginable to them would be the fact that there are organisms that live, and grow, in these environmental extremes. R. D. MacElroy named these organisms lovers (from the Greek “philos”), “extremophiles” as in “lovers of extreme environments”. The discovery of extremophiles has put vitality in the biotechnology industry as this discipline has exploded in the past 20 years. Several reviews have been published on extremophiles and an increasing number of meetings and conferences are organised around the theme. Genomes of extremophiles have been sequenced, patents have been filed and several funding programmes have been launched namely the US National Science Foundation and NASA’s programmes in “Life in Extreme Environments, Exobiology and Astrobiology”, and the European Union’s “Biotechnology of Extremophiles” and “Extremophiles as Cell Factories”(...) Description: Dissertation presented to obtain the Ph.D degree in Biochemistry

2011-09-01T00:00:00Z Oliveira, Tânia Filipa http://hdl.handle.net/10362/5763 2011-06-09T15:11:31Z 2011-01-01T00:00:00Z

Title: Crystallographic and biochemical studies on dissimilatory sulfite reductases Authors: Oliveira, Tânia Filipa Abstract: Life on earth is only possible through tightly interwoven material transformations through various cycles. Carbon, nitrogen, fosforous and sulfur, with a special interest in the latter, are essential components of all living organisms and represent the most important elements circulating within the biosphere. During this circulation, sulfur can be found in various oxidation states with transformations occurring both biological and chemically. Dissimilatory sulfate reduction is one of those reactions, where sulfate is reduced to the final product sulfide in order to obtain energy for their metabolism. Sulfate reduction however, is not a favourable energetic reaction, and so sulfate is initially activated to adenosine-5’-phosphosulfate (APS) by ATP sulfurylase. APS is then reduced to sulfite by APS reductase allowing the sulfite reductase to reduce sulfite to the final product sulfide in a six electron transfer reaction. This last step can occur in an assimilatory or dissimilatory way.(...) Description: Thesis dissertation presented to obtain a PhD degree in Biochemistry at Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa

2011-01-01T00:00:00Z