Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orangeyellow color w-hen treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.

Colorimetric Method for Determination of Sugars and Related Substances

Use of Dinitrosalicylic Acid Reagent for Determination of Reducing Sugar

A statistical mechanical treatment of high polymer solutions has been carried out on the basis of an idealized model, originally proposed by Meyer, which is analogous to the one ordinarily assumed in the derivation of the ``ideal'' solution laws for molecules of equal size. There is obtained for the entropy of mixing of n solvent and N linear polymer molecules (originally disoriented), ΔS=−k[(n/β) ln v1+N ln v2] where v1 and v2 are volume fractions and β is the number of solvent molecules replaceable by a freely orienting segment of the polymer chain. This expression is similar in form to the classical expression for equal‐sized molecules, mole fractions having been replaced by volume fractions. When the disparity between the sizes of the two components is great, this expression gives entropies differing widely from the classical values, which accounts for the large deviations of high polymer solutions from ``ideal'' behavior. The entropy of disorientation of a perfectly arranged linear polymer is found t...

Thermodynamics of High Polymer Solutions

[17] Amylases, α and β

Publisher Summary The vibrational spectrum of a molecule is determined by its three-dimensional structure and its vibrational force field. An analysis of this (usually infrared (IR) and Raman) spectrum can therefore provide information on the structure and on intramolecular and intermolecular interactions. The more probing the analysis, the more detailed is the information that can be obtained. Detailed analyses of the vibrational spectra of macromolecules, however, have provided a deeper understanding of structure and interactions in these systems. An important advance in this direction for proteins came with the determination of the normal modes of vibration of the peptide group in N-methylacetamide, and the characterization of several specific amide vibrations in polypeptide systems. Extensive use has been made of spectra-structure correlations based on some of these amide modes, including attempts to determine secondary structure composition in proteins. Polypeptide molecules exhibit many more vibrational frequencies than the amide modes. Over the years, some normal-mode calculations have provided greater insight into the spectra of particular molecules. However, these have often been based on approximate structures or have employed limited force fields. These force fields can now serve as a basis for detailed analyses of spectral and structural questions in other polypeptide molecules. The aim of this chapter is to present these recent developments in the vibrational spectroscopy of peptides, polypeptides, and proteins.

Vibrational spectroscopy and conformation of peptides, polypeptides, and proteins.

Les propriétés des polymères en solution X. Ultrafiltrations de solutions de caoutchouc

Les propriétés de polymères supérieurs en solution. III. Action de la lumière ultra-violette sur le caoutchouc dissous

IN a series of communications in NATURE, Dr. D. M. Wrinch1 has put forward a new hypothesis on the structure of certain proteins—the ‘cyclol-theory’. According to this, peptide chains should be capable of uniting to form two- and three-dimensional nets, three peptide residues forming a ring as in II: A, C, and E represent residues of the type R.CO.NH.CHR- ; B, D, and F residues of the type R.NH.CHR.CO-.

Possibility of the Formation of Cyclols from Simple Peptides

Synthèse d'hydrocarbures ramifiés à longue chaîne

FOLLOWING the discovery by Bernal and Crowfoot1 of the sharp diffraction spectra obtained from single pepsin crystals, Wyckoff and Corey2 showed that with suitable technique certain other micro-crystalline proteins (for example, oxyhaemoglobin) give diagrams with spacings between 10 A. and 40 A.

Kurt H. Meyer

Papers

Les propriétés des polymères en solution X. Ultrafiltrations de solutions de caoutchouc

Les propriétés de polymères supérieurs en solution. III. Action de la lumière ultra-violette sur le caoutchouc dissous

Possibility of the Formation of Cyclols from Simple Peptides

Synthèse d'hydrocarbures ramifiés à longue chaîne

Diffraction of X-Rays by Bence-Jones Protein