María, llena de gracia y libre de pecado

Pregón de la Inmaculada 201

A unified concept of energy transduction by biochemical systems

Electronic energy —resulting either from electron excitation or localization — is the obligatory link between the different forms of energy (light, redox, acid-base, metahosphate-ortophosphate) transducible by biochemical systems. The key in energy coupling between any two transducing systems lies precisely in the fact that both of them share a common intermediate that cyclically participates in the overall transduction process by alternating between its electronically energized state and its unenergized basal state. All the energy-transducing biochemical systems must operate, according to their nature and character of the energization, at two midpoint redox potentials, at two pKa's, or at two phosphate transfer potentials. Three basic energy-transducing systems in bioenergetics, namely, redox, acid-base and metaphosphate- ortophosphate, couple between them through the acylium cation [R-C=0]**— carboxylate anion (R—COO") pair. These forms are, respectively, twice-energized and unenergized and can accept, at two energy levels, either two electrons or two protons or the ortophosphate anion (H2PO4") and the "zwitterion" metaphosphate (~PÕ3"**). Both at the substrate level and at the membrane level, ortophosphate energization to metaphosphate, by removal of an oxide anion (02~), brings about a decrease in pKa with the concomitant dissociation of the two protons (2Ht ) , whereas deenergization of metaphosphate to ortophosphate, by addition of an oxide anion, brings about an increase in pKa with the concomitant fixation of two protons. One of the greatest discoveries of bioenergetics was the introduction in cell metabolism of the one-electron redox photosystem chlorophyll a and was followed by the starting of the one-electron/one-proton redox/acid-base energytransducing systems of the photosynthetic and respiratory electron transport chains

Ochoa, hombre de ciencia y de bien

Como homenaje, lleno de admiración, gratitud y afecto a su memoria, este artículo es una biografia científica y humana del profesor Ochoa ( 1905- 1993), una de las autoridades más sobresalientes de la bioquímica clásica -que brilló con magnificencia en la primera mitad de este siglo- y uno de los fundadores de la biología molecular, nacida con vigor y grandeza en la década de los 50. Después de su educación inicial en Málaga, Severo Ochoa ingresó en la Universidad de Madrid en 1922 para estudiar medicina bajo la influencia del famoso neuroanatomista Ramón y Cajal y fue seleccionado para trabajar bajo la dirección del profesor de fisiología Negrín. De 1929 a 194 1, Ochoa trabajó en Alemania con Meyerhof, en Inglaterra con Dale y Peters y en Estados Unidos con los Cori. Después de su larga peregrinación, su destino fue Nueva York, donde fue nombrado investigador asociado y profesor de bioquímica y llevó a cabo la mayoría de sus célebres descubrimientos durante el período 1942-1974, en que se trasladó a Nutley hasta la fecha de su vuelta definitiva a Madrid en 1985. Ochoa es el padre de la fosforilación oxidativa y el descubridor de la polinucleótido fosforilasa, el enzima que cataliza la formación del ácido ribonucleico a partir de los nucleósido- difosfatos, y también contribuyó decisiva mente a la elucidación de algunas de las reacciones fundamentales de la fotosíntesis y del metabolismo intermediario, al desciframiento del código genético y a la biosíntesis de proteínas. Ochoa fue galardonado en 1959 con el Premio Nobel de fisiología o medicina, que compartió con su antiguo discípulo Arthur Komberg.As a homage, full of admiration, gratitude and affection, to his memory, this article is a scientific and human biography of professor Ochoa ( 1905- 1993), one of the most outstanding authorities of c1assic biochemistry -which shone with magnificence in the first half of this century- and one of the founders of modem molecular biology, bom with vigour and grandeur in the late 1950 , . After his initial education in Málaga, Severo Ochoa entered Madrid University in 1922 to study medicine under the influence exerted upon him by the famous neuroanatomist Ramón y Cajal and was selected to work under the direction of the professor of physiology Negrin. From 1929 to 1941, Ocho a worked in Germany with Meyerhof, in England with Dale and Peters, and in USA with the Coris. After Ochoa's long peregrination, his destination was New York, where he became research associate and professor of biochemistry and carried out most of his celebrated discoveries during the period 1942-1974 , when he moved to Nutley until the date of his definitive retum to Madrid in 1985. Ochoa is the father of oxidative phosphorylation and the discoverer of polynucleotide phosphorylase, the enzyme which catalyzes the formation of ribonuc1eic acid from nuc1eoside diphosphates. He al so contributed decisively to the elucidation of sorne fundamental reactions in photosynthesis and intermediary metabolism, the breaking of the genetic code and the biosynthesis of proteins. Ochoa was awarded the 1959 Nobel Prize for physiology or medicine, sharing it with his former student Arthur Komberg

Del Corazón y la Mente

El trabajo del Prof. Losada inaugura una colección que incluirá temas abiertos a la dimensión humanística de nuestra Academia y que llamaremos «Lecturas Singulares». El lector tiene hoy en sus manos un texto que le descubrirá los senderos de la ciencia escrutando la naturaleza, desde el «big-bang», la gran estampida, a la biología molecu- lar, la electrofisiología y la mente. A la vez encontrará el latido del corazón, los sentimientos, lo indefinible y el horizonte de la esperanza humana