LINUS

Linus Pauling is portrayed on this 1977 Volta stamp The chemical formulas depict the two resonance forms of ben zene and the explosion in the background symbolizes Pauling s efforts to limit the testing of nuclear weapons... 

Linus Pauling (1901-1994) was born in Portland Ore gon and was educated at Oregon State University and at the California Institute of Technology where he earned a Ph D in chemistry in 1925 In addition to re search in bonding theory Pauling studied the structure of proteins and was awarded the Nobel Prize in chemistry for that work in 1954 Paul ing won a second Nobel Prize (the Peace Prize) in 1962 for his efforts to limit the testing of nuclear weapons He was one of only four scientists to have won two Nobel Prizes The first double winner was a woman Can you name her" ... 

The primary structure of a peptide is its ammo acid sequence We also speak of the secondary structure of a peptide that is the conformational relationship of nearest neighbor ammo acids with respect to each other On the basis of X ray crystallographic studies and careful examination of molecular models Linus Pauling and Robert B Corey of the California Institute of Technology showed that certain peptide conformations were more stable than others Two arrangements the a helix and the (5 sheet, stand out as... 

Sickle-cell anemia is the classic example of an inherited disease that is caused by a change in a protein s amino acid sequence. Linus Pauling proposed in 1949 that it was caused by a defect in the hemoglobin molecule he thus coined the term molecular disease. Seven years later Vernon Ingram showed that the disease was caused by a single mutation, a change in residue 6 of the P chain of hemoglobin from Glu to Val. 

In a letter of unspecified date to a biologist, Linus Pauling is reported as writing (Anon 1998) "You refer to me as a biochemist, which is hardly correct. I can properly be called a chemist, or a phy.sical chemist, or a physicist, or an X-ray crystallographer, or a mineralogist, or a molecular biologist, but not, I think, a biochemist,"... 

Together with the structural principles established by the Bragg school concerning the many types of silicates, Goldschmidt s ideas were taken further by Linus Pauling in California to establish the modern science of crystal chemistry. A good early overview of the whole field can be found in a book by Evans (1939, 1964). 

It took a long time before everyone accepted the reality of quasicrystallinity. No less a celebrity than Linus Pauling took a hard line, and published a paper in Nature (Pauling 1985) insisting, erroneously as was finally proved some time later, that the pattern was caused by an array of minute crystals in twinned arrangement. 

Another recent database, still in evolution, is the Linus Pauling File (covering both metals and other inorganics) and, like the Cambridge Crystallographic Database, it has a "smart software part which allows derivative information, such as the statistical distribution of structures between symmetry types, to be obtained. Such uses are described in an article about the file (Villars et al. 1998). The Linus Pauling File incorporates other data besides crystal structures, such as melting temperature, and this feature allows numerous correlations to be displayed. 

The concepts of directed valence and orbital hybridization were developed by Linus Pauling soon after the description of the hydrogen molecule by the valence bond theory. These concepts were applied to an issue of specific concern to organic chemistry, the tetrahedral orientation of the bonds to tetracoordinate carbon. Pauling reasoned that because covalent bonds require mutual overlap of orbitals, stronger bonds would result from better overlap. Orbitals that possess directional properties, such as p orbitals, should therefore be more effective than spherically symmetric 5 orbitals. 

As high technology continues to transform the modern biochemical laboratory, it is interesting to reflect on Linns Pauling s discovery of the u-helix. It involved only a piece of paper, a pencil, scissors, and a sick Linus Pauling, who had tired of reading detective novels. The story is told in the excellent book The Eighth Day of Creation by Horace Freeland Judson ... 

FIGURE 6.40 A comparison of the structures of four protein domaius aud predictions of these structures by the program LINUS by Rose aud Sriuivasau. (Professor George Rnse/Johns Hopkins University)... 

Srinivasan, R., and Rose, G. D., 1995. LINUS A hierarchic procedure to predict the fold of a protein. Proteins Structure, Function and Genetics 22 81-99. 

An answer was provided in 1931 by Linus Pauling, who showed how an s orbital and three p orbitals on an atom can combine mathematically, or hybridize, to form four equivalent atomic orbitals with tetrahedral orientation. Shown in Figure 1.10, these tetrahedrally oriented orbitals are called sp3 hybrids. Note that the superscript 3 in the name sp3 tells how many of each type of atomic orbital combine to form the hybrid, not how many electrons occupy it. 

Pauling, Linus Carl, 12 PCC, see Pyridinium chlorochromate PCR, see Polymerase chain reaction, 1117-1118... 

In the 1930s a theoretical treatment of the covalent bond was developed by, among others, Linus Pauling (1901-1994), then at the California Institute of Technology. The atomic orbital or valence bond model won him the Nobel Prize in chemistry in 1954. Eight years later, Pauling won the Nobel Peace Prize for his efforts to stop nuclear testing. 

It is possible to write a simple Lewis structure for foe S042- ion, involving only single bonds, which follows foe octet rule. However, Linus Pauling and others have suggested an alternative structure, involving double bonds, in which foe sulfur atom is surrounded by six electron pairs. 

Pascal An SI unit of pressure the pressure exerted by the force of 1 newton on an area of 1 square meter, 104,635 Paschen series, 138 Pasteur, Louis, 601 Pauli exclusion principle, 141-143 Pauling, Linus, 185 Pentyl propionate, 596t Peptide linkage The—C—N—group... 

There is no chemistry course given today that is not influenced by the ideas of Linus C. Pauling. He is a man of broad imagination, dramatic personality, and boundless inspiration. Mankind will long benefit because he chose to explore the frontiers of science. 

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