Quinoid pigments of echinodermata III. Minor pigments of the sea urchin Strongylocentrotus nudus

Summary 1. 3-Acetyl-2,7-dihydroxy-6-methylnaphthazarin, not previously described, has been isolated from the test and needles of the sea urchinStronglyocentrotus nudus.2. The pigments of this sea urchin have been shown to include 2,7-dihydroxynaphthazarin and spinochrome E.3. A number of minor pigments forming naphthazarin derivatives has been isolated. One of them is connected with spinochrome C by mutual transformations.The subject matter of the present paper was given in part at the All-Union Conference on Biological Resources of the Seas of the Far East (Vladivostok, 1975).Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 202–207, March–April, 1977.     

Decarbonylation Path of 5-Phenyl-2,3-dihydrofuran-2,3-dione: Ab Initio Calculations

The gradient path of decarbonylation of 5-phenyl-2,3-dihydrofuran-2,3-dione in the gas phase was calculated ab initio [RHF/6-31G(d)]. It includes formation of a planar transition state which is less polar than the initial compound.     

Raman scattering in the disordered phase of ammonium halides

The Raman scattering spectra of pure and mixed ammonium halide crystals are presented. A correlation between the halogen concentration in the samples and the frequency of the outer translational mode is shown. Experimental results and theoretical models are compared.     

Precipitation of trypsin with polymethacrylic acid

Conclusions It has been shown that the precipitation of trypsin with polymethacrylic acid results in a reversible or irreversible (after an incubation period) formation of a complex and, in the latter case, a stable, nonactive addition product can be isolated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1895–1896, August, 1970.