http://macromoleculas.unq.edu.ar

bmacro05@yahoo.comPasword: lactamasa

Friedrich August Kekule (1829-1896)

El concepto de macromolécula surgió naturalmente a principios del siglo XIX

Eduard Pfluger1875 Teoría de la respiración intracelular

Biuret

Análisis elemental: en 300 g de hemoglobina hay 1 g de hierroFórmula mínima: 1 mol de hemoglobina por mol de hierro

(16000 g de hemoglobina por 56 g de hierro)Peso Molecular: n16000

Emil Fischer (premio Nobel 1902)

Las proteínas están constituídas por péptidos de hasta 30 residuos

Existen unos treinta aminoácidos naturales, por lo tanto los isómeros posibles son 30!=31032

En realidad el cálculo es 3030=31044

La teoría de los biocoloides

•Alfred Werner postula la existencia de dos tipos de valencia química

•Aparecen los primeros datos de rayos X aplicados a fibras y las celdas unitarias son pequeñas

•Aparece la biocoloidología, bautizada como “the dark age” por Florkin

El axioma de la biocoloidología fue:

El estado coloidal es un nuevo estado de la materia al cual no se aplican las leyes convencionales de la química

Herman Staudinger (1881-1965)

Premio Nobel 1953

El debate sobre las macromoléculas

In many instances a polymeric compound can be transformedinto derivatives of a different type without any change in the degreeof polymerization of the compound in exactly the same way as small molecules can be transformed. A polymer compound can hence be transformed into polymer analogous derivatives, the transformation proving that all the basic molecules contained in the colloid particles of these polymeric compounds are linked together by chief valences, in other words the colloid particles are macromolecules. This proof becomes especially clear because out of a series of polymer homologues various ones can be transformed into polymeranalogous derivatives.

HE R M A N N S T A U D I N G E RMacromolecular chemistryNobel Lecture, December 11, 1953

Theodor Svedberg (1884-1971)

Premio Nobel 1926

Taxol

vitamina B12 (200 átomos)

glutamato sintasa1 cadena, 1500 residuos,

20000 átomos

proteína A1 cadena, 60

residuos, 900 átomos

Síntesis modularsíntesis disociada del plegado

Síntesis no modularla estructura está acopladadirectamente a la síntesis

Complejidad estructural y estrategia de síntesis

Sir William Henry Bragg(1862-1942)

Sir William Lawrence Bragg(1890-1971)

Premio Nobel compartido 1915

Cristal gigante de fosfato ácido de potasio (300 kg)

DNA (Bell, Atsbury)

William BraggLawrence Bragg

Dorothy Crowfoot (1910-1994)Premio Nobel 1964

IA-2

pChPylSCP2

2qt7.pdb

Cristalografía en la UNQ (LEPP)

armadillo ACBP (2fdq.pdb)

Atsbury under attack

Linus Pauling(1901-1994)Premio Nobel1954 y 1962

Pauling had been practically apolitical until World War II, but the war changed his life profoundly, and he became a peace activist. During the beginning of the Manhattan Project, Robert Oppenheimer invited him to be in charge of the Chemistry division of the project, but he declined saying that he was a pacifist. In 1946 he joined the Emergency Committee of Atomic Scientists, chaired by Albert Einstein, whose mission was to warn the public of the dangers associated with the development of nuclear weapons. His political activism prompted the U.S. State Department to deny him a passport in 1952, when he was invited to speak at a scientific conference in London. His passport was restored in 1954, shortly before the ceremony in Stockholm where he received his first Nobel Prize. Joining Einstein, Bertrand Russell and 8 other leading scientists and intellectuals he signed the Russell-Einstein Manifesto in 1955.

In 1957, Pauling began a petition drive in cooperation with biologist Barry Commoner, who had studied radioactive strontium-90 in the milk teeth of children across North America and concluded that above-ground nuclear testing posed public health risks in the form of radioactive fallout. He also participated in a public debate with the atomic physicist Edward Teller about the actual probability of fallout causing mutations. In 1958, Pauling and his wife presented the United Nations with a petition signed by more than 11,000 scientists calling for an end to nuclear-weapon testing. Public pressure subsequently led to a moratorium on above-ground nuclear weapons testing, followed by the Partial Test Ban Treaty, signed in 1963 by John F. Kennedy and Nikita Khrushchev. On the day that the treaty went into force, the Nobel Prize Committee awarded Pauling the Peace Prize, describing him as "Linus Carl Pauling, who ever since 1946 has campaigned ceaselessly, not only against nuclear weapons tests, not only against the spread of these armaments, not only against their very use, but against all warfare as a means of solving international conflicts." Interestingly, the Caltech Chemistry Department, wary of his political views, did not even formally congratulate him. However, the Biology Department did throw him a small party, showing they were more appreciative and sympathetic toward his work on radiation mutation.

Many of Pauling's critics, including scientists who appreciated the contributions that he had made in chemistry, disagreed with his political positions and saw him as a naïve spokesman for Soviet communism. He was ordered to appear before the Senate Internal Security Subcommittee, which termed him "the number one scientific name in virtually every major activity of the Communist peace offensive in this country." An extraordinary headline in Life magazine characterized his 1962 Nobel Prize as "A Weird Insult from Norway." Pauling was awarded the International Lenin Peace Prize by the USSR in 1970.

It is further assumed that each nitrogen atoms forms a hydrogen bond with an oxigen atom from another residue, with the nitrogen-oxygen distance equal to 2.72A, and that the vector from the nitrogen atom to the hydrogen bonded oxygen lies not more than 30 degrees from the N-H direction.

Solution of this problem shows that there are five and only five configuración for the chain that satisfy the conditions other than that of direction of the hydrogen bond relative to the N-H direction... 165, 120, 108 97.2, and 70 degrees for the rotational angle...

...the fourth and fifth are satisfactory, the angle between the N-vector and N-O vector being about 10 and 25 degrees for these two structures, respectively. The fourth structure has 3.69 residues per turn, and the fifth 5.13.