Showing papers in "Journal of the American Chemical Society in 1950"

The path of carbon in photosynthesis. V. Paper chromatography and radioautography of the products.

Abstract: Investigation of the reduction of carbon dioxide in plants requires a rapid and general method for separating and identifying a large number of compounds. Paper chromatography is such a method. This paper constitutes a report of progress in the development of experimental procedures in the application of paper chromatography to the separation of compounds formed by plants during short periods of photosynthesis. The compounds involved are important intermediates of plant and animal metabolism. These methods should find application not only in other biochemical problems, but in the control of chemical synthesis2 as well. A number of products formed during a short period of photosynthesis with radioactive carbon dioxide have been r e p ~ r t e d . ~ ~ * ~ ~ , ~ ~ ~ The classical biochemical methods and ion exchange techniques which were used in those identifications would require considerable effort to separate the large number of compounds involved. The success of paper chromatography in separating two groups of compounds important in phytosynthesis, amino acidss and s u g ~ t r s , ~ ~ ~ ~ prompted the present work on separation of polycarboxylic acids and phosphate esters. These compounds constitute the presently known intermediates in synthesis of plant material. l1 The primary requisite for the use of this method is some means of determining the position of a compound in the chromatogram. Both chemical and physical methods have been used. The former includes color tests which depend on development of a color directly on the paper by the use of specific reagents: ninhydrin for amino acids,*naphthoresorcinolor Tollens reagent for sugars,’” ferric ion for hydroxamic acid^,'^^^^ $H in-

Chromatographic Separation of Sugars on Charcoal1

Abstract: constant dielectric constants 75.25, 66.57 and confirmed the enhanced dielectric constant effect. 54.29 a t all three temperatures. These enhanced dielectric constant effects upon The equation proposed by Amis and JafFe the rate in acetone-water media were less by an accounted for the ionic strength data, but reorder of magnitude than has been observed when vealed a dielectric constant effect which, while ethyl alcohol-water was used as a solvent. Thus in the right direction, was magnified by an order part of the enhancement is solvent dependent. of magnitude. Coulombic energy calculations FAYETTEVILLE, ARKANSAS RECEIVED MARCH 22, 1949

Two hydrogen-bonded spiral configurations of the polypeptide chain

Abstract: During the past fifteen years we have been carrying on a program of determination of the detailed atomic arrangements of crystals of amino acids, peptides, and other simple substances related to proteins, in order to obtain structural information that would permit the precise prediction of reasonable configurations of proteins. We have now used this information to construct two hydrogen-bonded spiral configurations of the polypeptide chain, with the residues all equivalent, except for variation in the side chain.