Date of Birth: 03/26/1916
Place of birth: Monessen
Citizenship: United States
Back in 1940 in the United States, Alexander received a scholarship to Harvard University. Three years later, there he was awarded a doctorate in biochemistry, and he became a lecturer in the Faculty of Biological Chemistry at Harvard Medical School in Boston. In 1944 ... 1946. He serves on the civil position in the Office of research and development works of the United States. During the academic 1947/48, he was a junior researcher at the American Cancer Society office biochemical Nobel Institute in Sweden, where he worked under the leadership of Hugo Theorell. After returning to the US of A. I became an associate professor at Harvard, but at the end of the year left the post and heads the Laboratory of Cellular Physiology at the National Cardiology Institute, which is part of the National Health Council (NHS) in Bethesda (Maryland).
In his doctoral dissertation A. described his research on the development of methods for measuring the activity of enzymes that are in the retina. Enzymes - a chain of amino acids that control chemical reactions in living organisms. Since enzymes are more catalytic and non-structural proteins (protein similar muscle), they control the reactions themselves without engaging them. When Alexander started this work, it was known that an amino acid chain is twisted into a three-dimensional spherical shape. It was assumed that each type of protein twisted, although it is not known how, and takes a certain, only the characteristic shape for him, which is related to its function. However, no one at the time had not yet determined the complete amino acid sequence of an enzyme, and did not know anything about how enzymes control a huge set of known biochemical reactions.
A thought for the understanding of the relationship of structure and function of enzymes necessary to study the process of collecting living organisms. In the mid 40-ies. he and his colleague David Steinberg began to explore the process of inclusion of amino acids labeled with isotopes into proteins. Previously, Frederick Sanger at Cambridge University in England determined the sequence of the 51th amino acid of the protein insulin. Applying the methods of Sanger in his studies, Alexander suggested that if he synthesizes a chain of amino acids by attaching them one by one, and will measure its activity after each stage, he will be able to accurately determine the relationship between the properties of the enzyme and the amino acid sequence. For his research, he chose ribonuclease bull - an enzyme consisting of 124 amino acids and synthesized in the pancreas. Cleaving the nucleotide chain ribonucleic acid (RNA) in food, ribonuclease makes it possible to reuse in the body of the chain components.
Almost at the same time, the research group of the Rockefeller Institute (now Rockefeller University), led by Stanford Moore and William H. Stein, started working on a similar problem. A. Soon realized that this group can determine the amino acid sequence of the enzyme before it will make it himself.
Award Rockefeller Award allowed A. to take a vacation in the NHS and to hold academic 1954/55, in the Carlsberg Laboratory, working under the leadership of Kai Linderstrema-Lang. As a physical chemist, Linderstrem A. Lang helped in the study of enzymes, "depriving these organic compounds - as Alexander later wrote himself - these large non-crystalline macromolecules veil of mystery." Planning initially do only the synthesis of the enzyme, it nevertheless decided to proceed to the study of the entire ribonuclease molecule, watching her in a variety of conditions.
While it was known that proteins are denatured (lose its activity) in various chemical environments. Denaturation may occur when the forces supporting the chain of amino acids (primary structure) to a certain tightly packed configuration (tertiary structure), are destroyed, translating proteins in random coil state. One of the factors supporting the tertiary structure is the presence of disulfide-bridges, bonds that are formed between the sulfur-containing amino acids, cystine. A partially unwound ribo-nuclease, denaturing it, and chemically breaking it contains four disulfide bonds, to produce a single randomly twisted (and thus inactive) chains of amino acids. Then he discovered that, when this structure is converted into a disordered chemical environment that resembles the one in which the body is in the ribonuclease, the initial active tertiary structure is gradually restored.
By 1962 Alexander completed physico-chemical research, which has demonstrated its "thermodynamic hypothesis". In accordance with his point of view, ribonuclease active tertiary structure is formed due to rearrangement of amino acids under physiological conditions, with this configuration has the lowest energy and is therefore the most stable. Only one determines the amino acid sequence and tertiary structure of the enzyme and its functional activity.
In 1962, Alexander left the NHS and became a professor of biochemistry at Harvard Medical School, but next year he returned and headed the Laboratory of Chemical Biology at the National Institute of Arthritis, Metabolism and digestive system diseases. Here, during the 60s. he studied the structural and functional relationships of many proteins. Realizing that can simplify your work by using an enzyme that does not contain disulfide bonds, A. studied molecule nuclease of bacteria Staphylococcus aureus. By 1970, the enzyme was finally synthesized by researchers at the Rockefeller University.
"For his work on ribonuclease, especially concerning the connection between the amino acid sequence and the biologically active konfermentami", A. was awarded half the Nobel Prize in Chemistry for 1972, Moore and Stein shared the second part of the premium for the same work. In a speech at the presentation of a member of the Royal Swedish Academy of Sciences Po H. Malmstrom congratulated the three winners, who were armed by other researchers` approach to address the problems of enzymatic activity at the molecular level. " Malmstrom said that the special interest of A. was focused on the mechanism responsible for the configuration of the peptide chains. "In a series of elegant experiments it has shown that the necessary information is contained in a linear sequence of amino acids of peptide chains that no additional genetic information that is greater than that which is contained in the DNA is not required."
After receiving the Nobel Prize A. interested interferon - a protein that plays a key role in protecting the body against viruses and cancer. After isolation of the substance, he undertook a series of studies on its structure and properties. In 1982, he received the post of professor of biology at Johns Hopkins University.
In 1941 he married Florence A. Bernays Kenendzher; they have three children - two daughters and a son. In 1978 they divorced.
The following year he married Libby A. Esther Schulman-Eli. In his spare time he is engaged in sailing and listening to music.
Alexander is a member of the Board of the Weizmann Institute of Science in Rehovot (Israel) and a member of the American Society of Biochemistry, the US National Academy of Sciences and the Royal Danish Academy. In 1954 he won the civil service of the Rockefeller Foundation. He was awarded honorary degrees by Sortmor College, Providence College, New York Medical College, and Georgetown. Pennsylvania and Bransdeyskogo universities.