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 This expression is similar in form to the classical expression for equal‐sized molecules, mole fractions having been replaced by volume fractions.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.

Recherches sur l'amidon XXIII. La composition de l'amidon de feuilles, de germes et de tubercules de pommes de terre

IN an interesting paper which appeared recently in Nature, Goldacre and Lorch1 put forward the hypothesis that folding and unfolding of protein chains plays a decisive part in amœboid movement and cytoplasmic streaming. The same hypothesis was put forward more than twenty years ago by us in connexion with a new theory of muscular contraction2. This theory said that the contraction is due to a folding of unfolded protein chains under the influence of chemical reactions, and as one of the possibilities a variation of pH was considered; this was illustrated in 1929 by the accompanying diagram.

Biological significance of folding and unfolding of protein molecules.

IF cellulose is precipitated from solution or liberated from its compounds with sodium hydroxide, the space lattice (a = 8·14 A., b = 10·3 A., c = 9·14 A., β= 62°) differs from that of native cellulose (a = 8·35 A., b = 10·3 A., c = 7·9 A., (β= 84°). In this form it is known as hydrate cellulose, although it is in fact of the same analytical composition as the native form, and is free from water. Hitherto it has not been possible to convert one modification directly into the other ; it was possible to pass from native cellulose via alkali cellulose to hydrate cellulose, and from this (as Barry, Peterson and King1 showed recently) by way of the ammonia compound back to native cellulose. Moreover, Hess and Gundermann2 have described the appearance of native cellulose along with hydrate cellulose during the washing out of alkali cellulose at 100° C. We find, however, that it is possible to convert hydrate cellulose directly into native cellulose.

Kurt H. Meyer

Papers

Recherches sur l'amidon XXIII. La composition de l'amidon de feuilles, de germes et de tubercules de pommes de terre

Biological significance of folding and unfolding of protein molecules.

Transformation of Hydrate Cellulose into Native Cellulose

230. Les propriétés thermoélastiques du caoutchouc

Die Eisenchlorid‐Reaktion der Enole. Über Keto‐Enol‐Tautomerie. IV