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NEW BOOKS
NEW BOOKS Advances i n Enzymology a n d Related Su,bjects of B i o c h e m i s t r y , 1-01,111. Edited by F. F. XORDA K D C,. H. K E H K J I ~408 K .pp.; 12 illustrations. S e w T o r k : Interscience Publishers, Inc., 1943, Price: $5.50. The third volunie of this series of independent nionograplis consists of eleven articles. I n a n excellent review by A . E. AIirsky an account is given of biochemical investigations of chromosomes, viruses, und nuceloproteins. The chemical similarity of plant and animal chromosomes has been demonstrated, using Feulgen’s nucleal reaction, which has also provided the evidence for the occurreiice of desosyribose nucleic acid in the nuclei but not in the cytoplasm of all cells. Improved spectroscopic niethods permit detection of as small a n amount of nucleic acid ns lo-” mg. and provide a means of following quantitatively its variations during cell c!ivision or during metabolic processes. Desoxyribose nucleic acid can be obtained from tlic nucleus and ribose nucleic acid from the cytoplasmic moiety with new methods of separation. T h e chemical nature of the chromosome is gradually being elucidated, but only indirect evidence is available concerning the chemical nature of the gene, based mainly on the effectiveness of monochromatic ultraviolet radiation in producing mutations. T h e effects of tenipeniture on enzyme kinetics have been reviewed and reinterpretated by Irivin W . Sizer. Energies and entropies of activation are reported for the heat inactivation of twenty-eight different enzymes, but corrections will have t o be made for some of the values when the pure enzymes become available. Steps in activation leading to dennturation seem t o involve the rupture of salt bridges between acidic and basic groups held together by hydrogen bonds and the breaking of covalent bonds like cystine bridges. E n zyme reactions follow the hrrlienius equation over a wide temperature range. The activation energy seenis to t)e unaffected by environmental conditions, such as purity of the enzyme. T h e action of an enzyme on different substrates is characterized by the same activation energy. Physiological processes occurring inside the cell follow the ;\rrhenius equation and can be esplained i n ternis of enzyme kinetics. “);-Rays and the Stoichiometry of the Proteins” is the title of a n article by W . T. Astbury, dealing with distribution and properties of amino acid residues in proteins. Preliminary chemical evidence is presented indicating that a 2” 37’1 rule may describe the occurrence of amino acid residues in proteins where n and tn are positive integers or zero. Results obtained for some proteins like edestin support this rule, while others like egg albumin do not fit into this scheme. Fibrous proteins are classified according t o their s-ray diRraction patterns. Chemical and s-ray evidence is reviened on the structure of silk fibroin, the structures of the keratin-niyosin and the collagen group of fibrous proteins. The esisting x-ray d a t a are inconsistent with the cheniical d a t a , in that amino acid residues do not follow one another in the periods suggested by their relative proportions. Aimodel is proposed which correlates s-ray and chemical d a t a and vihicli is based on tlie principle t h a t polar and non-polar side chains occur alternately in the polypeptide chains. Insulin, lactoglobulin, egg albumin, hemoglobin, and tobacco mosaic virus are also considered. K u r t H . hleyer has written the chapter on the chemistry of glycogen. Qualitative detection and various methods of quantitative determination are reviewed. Improved isolation procedures are adopted whereby native glycogen of high molecular weight is obtained. The shape, size, and niolecular weight of native nnd of partially decomposed glycogen are considered. hIetliods t h a t have proved reliable i n the analysis of st:trch are applied in determining the constitution of glycogen. Digestion of glycogen in the intestinal tract is mentioned briefly; a more detailed account is given of the rwcrsible processes of enz>-matic decomposition and synthesis of tlie glycogen stored u p in individual organs. Verdoperoxidase, the enzyme recently isolated by Kjell .Igner from leucocytes, has been reviewed by the sanie author. The method of preparation is given, and its enzyiilatic activity and spectroscopic properties are described and compared with those of other peroxidases.
