During the early 1950's there appeared reports, from time to time of the presence among the products elaborated by actinomycetes of antifungal antibiotics which exhibited very similar and very characteristic multipeaked ultraviolet absorption spectra. In 1954, with a good number of examples on record, these spectra were analyzed and identified as those of straight-chain conjugated polyenes, comprising tetraenes, pentaenes, hexaenes and heptaenes (85, I30). These antibiotics have since been commonly referred to as the polyene antifungal antibiotics to distinguish them from a host of other...

Diese Ubersieht soll die wesentliche Literatur uber Ubichinon und einige chemisch nahe v:erwandte naturliche Chinone bis etwa Oktober 1961 referieren. Der Name Ubichinon (englisch Ubiquinone) wurde von MORTON und Mitarb. (II3) fUr eine Substanzgruppe der allgemeinen Formel (I) vorgeschlagen. In MORTONS Arbeitskreis wurde die betreffende Substanz anfanglich als "Substanz SA" bezeichnet (Io8). Wie sieh aus spateren o II H3CO",/~~CH3 3112 4 116 CH 3 /"'/'" I H3CO III (CH2-CH=C-CH2)n-H o (1.) Untersuchungen ergeben hat, waren nicht aIle als SA bezeichneten Substanzen untereinander identisch; die...

Depuis l'isolement de la creatine par CHEVREUL, en 1832, dans les extraits de viande (44) et son identification par LIEBIG, en r847, l'attention des biochimistes a porte principalement, pendant longtemps, sur le role de l'arginine dans la production de l'uree (I28), sur le cyde de l'ureo- genese (I34) et sur celui de la phosphocreatine (7I) et de la phospho- arginine (r68, I69) dans la contraction musculaire. A la suite de la mise en evidence, d'une part des reactions de trans- amidination expliquant la convertibilite entre l'arginine et un certain nombre de derives guanidiques (28,29,33,73,2...

Substances belonging to this group of organic compounds are wi, lely distributed in Nature, being found in plants, both higher and lower fungi and, upto the present time, in one animal source, sheep wool-fat. For a long time no real differentiation was possible between the tetra- and penta cyclic triterpenes and the sterols. Then the two latter became disting uishable by their selenium. .dehydrogenation products, i. e., picene and naphthalene derivatives from the pentacyclic triterpenes and DIELS' hydrocarbon from the sterols. It is now apparent that those compounds yielding predominantly I:...

In agreement with SCHLENK (I78) "nucleotide" is here taken to mean a phosphoric ester of an N-glycoside of a heterocyclic base. Although they fall outside the scope of this definition, phosphorylated derivatives of riboflavin are added in recognition of their close relation to the main body of nucleotides. A complete review of even the organic chemistry of nucleotides and their derivatives would now form a substantial monograph. The smaller and less characteristic fragments of the nucleotides, namely the hetero cyclic bases, the component sugars and the derived sugar phosphates, are therefore...

In their monumental work "The Cactaceae," BRITTON and ROSE (I9) record 1235 species belonging to the three tribes which constitute the family of the Cacti. The actual number of the species must be con siderably higher. Cacti occur frequently in tlie more arid and less accessible regions of the American Continent, nearly always within very narrow and definite borderlines. The habitat of a species is in many instances a single valley located in a remote, uninhabited region of the Cordillera. Thus the collection of flowering specimens fit for botanical identification is some times extremely...