Phoebus Aaron Theodore Levene, M.D. (25 February,1869 – 6 September, 1940) was a Russian-American
biochemistBiochemists are scientists who are trained in biochemistry. Typical biochemists study chemical processes and chemical transformations in living organisms. The prefix of "bio" in "biochemist" can be understood as a fusion of "biological chemist."-Role:...
who studied the structure and function of
nucleic acidA nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within cells. The most common nucleic acids are deoxyribonucleic acid and ribonucleic acid . Nucleic acids are universal in living things, as...
s. He characterized the different forms of nucleic acid,
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
from
RNARibonucleic acid is a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate...
, and found that DNA contained
adenineAdenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...
,
guanineGuanine is one of the five main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, thymine, and uracil. In DNA, guanine is paired with cytosine. With the formula C
5H
5N
5O, guanine is a derivative of purine, consisting of a fused...
,
thymineThymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. As the name suggests, thymine may be...
,
cytosineCytosine is one of the four main bases found in DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached . The nucleoside of cytosine is cytidine...
,
deoxyriboseDeoxyribose, also known as
D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group in its linear structure...
, and a phosphate group.
He was born into a Jewish family as
Fishel Aaronovich Levin in Sagor in
LithuaniaLithuania , officially the Republic of Lithuania is a country in Northern Europe, the southernmost of the three Baltic states. Situated along the southeastern shore of the Baltic Sea, it shares borders with Latvia to the north, Belarus to the southeast, Poland, and the Russian exclave of...
,
RussiaRussia , officially known as both Russia and the Russian Federation , is a country in northern Eurasia . It is a semi-presidential republic, comprising 83 federal subjects...
but grew up in St.
Phoebus Aaron Theodore Levene, M.D. (25 February,1869 – 6 September, 1940) was a Russian-American
biochemistBiochemists are scientists who are trained in biochemistry. Typical biochemists study chemical processes and chemical transformations in living organisms. The prefix of "bio" in "biochemist" can be understood as a fusion of "biological chemist."-Role:...
who studied the structure and function of
nucleic acidA nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within cells. The most common nucleic acids are deoxyribonucleic acid and ribonucleic acid . Nucleic acids are universal in living things, as...
s. He characterized the different forms of nucleic acid,
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
from
RNARibonucleic acid is a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate...
, and found that DNA contained
adenineAdenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...
,
guanineGuanine is one of the five main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, thymine, and uracil. In DNA, guanine is paired with cytosine. With the formula C
5H
5N
5O, guanine is a derivative of purine, consisting of a fused...
,
thymineThymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. As the name suggests, thymine may be...
,
cytosineCytosine is one of the four main bases found in DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached . The nucleoside of cytosine is cytidine...
,
deoxyriboseDeoxyribose, also known as
D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group in its linear structure...
, and a phosphate group.
He was born into a Jewish family as
Fishel Aaronovich Levin in Sagor in
LithuaniaLithuania , officially the Republic of Lithuania is a country in Northern Europe, the southernmost of the three Baltic states. Situated along the southeastern shore of the Baltic Sea, it shares borders with Latvia to the north, Belarus to the southeast, Poland, and the Russian exclave of...
,
RussiaRussia , officially known as both Russia and the Russian Federation , is a country in northern Eurasia . It is a semi-presidential republic, comprising 83 federal subjects...
but grew up in St. Petersburg (Petrograd). There he studied medicine at the Imperial Military Medical Academy (M.D., 1891) and developed an interest in biochemistry. In 1893, because of anti-Semitic
pogromA pogrom is a form of riot directed against a particular group, whether ethnic, religious, or other, and characterized by killings and destruction of their homes, businesses, and religious centers...
s, he and his family emigrated to the United States and he practiced medicine in
New YorkNew York is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous. The state is bordered by New Jersey and Pennsylvania to the south, and Connecticut, Massachusetts and Vermont to the east...
.
Levene enrolled at
Columbia UniversityColumbia University in the City of New York is a private university in the United States and a member of the Ivy League. Columbia's main campus lies in the Morningside Heights neighborhood in the borough of Manhattan, in New York City...
and in his spare time conducted biochemical research, publishing papers on the chemical structure of sugars. In 1896 he was appointed as an Associate in the Pathological Institute of the New York State Hospitals, but he had to take time off to recuperate from tuberculosis. During this period, he worked with several chemists, including
Albrecht KosselLudwig Karl Martin Leonhard Albrecht Kossel was a German medical doctor.-Biography:Kossel was born in Rostock as the son of Prussian consul Albrecht Kossel and his wife Clara. In 1872, Kossel went to the University of Strasbourg to study medicine, where he visited lectures of Anton de Bary,...
and
Emil FischerEmil Fischer may refer to:* Emil Fischer , German dramatic basso* Franz Joseph Emil Fischer , German chemist* Hermann Emil Fischer , German chemist...
, who were the experts in proteins.
In 1905, Levene was appointed as head of the biochemical laboratory at the Rockefeller Institute of Medical Research. He spent the rest of his career at this institute, and it was there that he identified the components of
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
. (He had discovered
riboseRibose, primarily occurring as
D-ribose, is an organic compound that occurs widely in nature. It is an aldopentose, that is a monosaccharide containing five carbon atoms that, in its acyclic form, has an aldehyde functional group at one end. This species predominantly exists in the...
in 1909 and
deoxyriboseDeoxyribose, also known as
D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group in its linear structure...
in 1929.) Not only did Levene identify the components of DNA, he also showed that the components were linked together in the order phosphate-sugar-base to form units. He called each of these units a
nucleotideNucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides play central roles in metabolism...
, and stated that the DNA molecule consisted of a string of nucleotide units linked together through the phosphate groups, which are the 'backbone' of the molecule. His ideas about the structure of DNA were wrong; he thought there were only four nucleotides per molecule. He even declared that it could not store the genetic code because it was chemically far too simple. However, his work was a key basis for the later work that determined the structure of DNA. Levene published over 700 original papers and articles on biochemical structures. Levene died in 1940, before the true significance of DNA became clear.
Levene is known for his "tetranucleotide hypothesis" (formulated around 1910) which first proposed that DNA was made up of
equal amounts of adenine, guanine, cytosine, and thymine. Before the later work of
Erwin ChargaffErwin Chargaff was an Austrian Jewish biochemist who emigrated to the United States during the Nazi era...
, it was widely thought that DNA was organized into repeating "tetranucleotides" in a way that could not carry genetic information. Instead, the protein component of
chromosomeA chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions...
s was thought to be the basis of heredity; most research on the physical nature of the
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
focused on
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
s, and particularly
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
s and
virusA virus is an infectious agent too small to be seen directly with a light microscope. They are not made of cells and can only replicate inside the cells of another organism . Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, before the 1940s.
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