ON THE LUMINESCENCE OF L-TRYPTOPHANE AND l-TYROSINE IN AQUEOUS SOLUTION AT 77dK INDUCED BY X-RAYS AND U.V.-LIGHT

Abstract— The lumincscence arising from L-tryptophane and L-tyrosine in aqueous solutions at 77K during irradiation with u.v.-light and with X-rays has been studied. The spectra obtained with the two types of radiation were largely similar, differing only in that the yields of phosphorescence relative to fluorescence were considerably enhanced in the case of X-irradiation. The decay times observed for the exponentially decaying phosphorescence, being 6.6 sec and 2.7 sec for tryptophane and tyrosine respectively, were the same for both kinds of irradiation. The G-value of the X-ray induced luminescence was about 10 for both tryptophane and tyrosine. Thus, about 30 per cent of the total energy absorbed from X-rays in these compounds was re-emitted as light.
It was concluded that the X-ray induced fluorescence and phosphorescence originate from the same levels as does the luminescence caused by u.v.-light, i.e. the lowest excited singlet and the lowest triplet level of the aromatic structure of these compounds. In the case of X-irradiation the enhanced ratios between the yields of phosphorescence and fluorescence indicated that some process other than excitation directly from the ground state contributed considerably to the luminescence yields. Assuming this process to be a recombination between the ionized molecule and its electron, it was calculated that the contribution to the luminescence yield from excitations directly from the ground state relative to that from ionizations, was negligible for both compounds.     

Photosensitive decomposition of organic solvents at 77 degrees K by an aromatic amine, diphenylparaphenylenediamine

Abstract— –By e.s.r. we have studied the photoexcitation of an aromatic amine to its triplet state at 77°K, its photoionization to a radical cation and the simultaneous formation of solvent radicals proceeding from the photosensitization of the organic glassy matrix. In the case of methanol and ethanol matrix we observe approximately one solvent radical per solute radical cation. In the case of isopropanol and methyltetrahydrofuran we find respectively three and two solvent radicals per solute radical cation. The results suggest two possible processes of photosensitization. By successive absorption of two photons, the amine reaches an excited triplet state which is able either to dissociate giving one electron and one cation radical or to transfer its energy to the solvent, this last being decomposed. It is assumed that in the case of methanol and ethanol, the radicals from the solvent are only formed by reaction on the matrix by the released electron, whereas in the case of isopropanol and methyltetrahydrofuran, the second process is prevalent or exclusive.     

Electrophilic reactions of 3-hydroxyisonicotinic acid

Conclusions The aminomethylation, azo-coupling, and nitration of 3-hydroxyisonicotinic acid and its ester are directed to the 2 position, whereas their iodination proceeds with the formation of the 2-iodo and 2,6-diiodo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 452–454, February, 1977.     

Separation of alkylaminonaphthylenesulfonyl peptides and amin acids by high-performance liquid chromatography. Methods for measuring melanotropin inhibiting factor breakdown

N,N-Dimethyl diethyl, dipropyl, dibutyl, and N-monoisopropylaminoaphthylenesulfonyl derivatives of melanotropin inhibiting factor (MIF) and its metabolites were prepared, and their chromatographic behavior was investigated with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), using five solvent systems on polyamide layers and ten solvent systems on muBondapak C18 and muBondapak phenyl columns. A mixture of MIF and its metabolites derivatized with Dns chloride was adequately resolved by two-dimensional chromatography on polyamide layer with solvent systems, formic acid-water (3:97) and benzene-acetic acid (9:1). Bns-MIF and its metabolites were separated with muBondapak C18 column with the solvent system acetonitrile-0.01 M sodium sulphate buffer, pH 7 (50:50). They were separated into five groups: Gly and Bns acid; Pro-Leu, Leu-Gly and Leu; Pro; Gly-NH2; and MIF. The alkylaminonaphthylenesulfonyl derivates had strong fluorescence, which permitted their detection at the level of 10(-11) to 10(-9) mol. Dns-MIF and its derivatives had the lowest detectable amounts. HPLC with the aid of the Dns derivation is reliable and fast, and is the preferable method for study of neuropeptide breakdown.     

Preconcentration of manganese,cobalt, yttrium,zirconium, niobium,ruthenium, europium and protactinium by various hydroxides

Summary The removal of trace elements from dilute water solutions by hydroxide precipitates was investigated. The co-precipitation yields of manganese, cobalt, ruthenium, europium and protactinium onto beryllium, zinc, iron, lanthanum and titanium hydroxides were studied in the pH region from 3 to 11, while those of manganese, cobalt, yttrium, zirconium, niobium, ruthenium, europium, and protactinium onto the same hydroxides were investigated in sea-water media. The influence of some other factors, such as the presence of neutral electrolyte and NH₄ ⁺ ions, aging of hydroxide precipitates etc. on the co-precipitation yields were also examined.

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Zusammenfassung Die Entfernung von Spurenelementen aus verdünnten wäßrigen Lösungen durch Hydroxidniederschläge wurde untersucht. Die mitgefällten Anteile Mn, Co, Ru, Eu und Pa in den Hydroxiden von Be, Zn, Fe, La und Ti wurden im pH-Bereich 3–11 untersucht, während die Anteile von Mn, Co, Yt, Zr, Nb, Ru, Eu und Pa in den gleichen Hydroxiden in Meerwasser studiert wurden. Der Einfluß einiger anderer Faktoren auf die Mitfällung, wie die Anwesenheit neutraler Elektrolyte und von NH₄-Ionen, die Alterung der Hydroxidniederschläge usw. wurden ebenfalls geprüft.

     

Research in the isoxazole series

The 4-nitro derivative is formed in the nitration of 3,5-diphenylisoxazole (I) in acetic anhydride. Mononitration of isoxazole I in concentrated H₂SO₄ gave 3-phenyl-5-(p-nitrophenyl)isoxazole, while polynitration gave a mixture of dinitro derivatives, among which 3- (m-nitro-phenyl)-5-(p-nitrophenyl)isoxazole was identified. The structures of the isolated products were established by means of the spectra, by reaction-chromatography methods, and gasliquid chromatography, as well as by a comparison with genuine samples of the two mononitro and four dinitro derivatives of isoxazole I.     

RECOVERY OF HAEMOPHILUS INFLUENZAE FROM ULTRAVIOLET AND X-RAY DAMAGE

Abstract— Results of experiments on reactivation of ultraviolet (u.v.)-irradiated Haemophilus influenzae and cellular reactivation of u.v.-damaged transforming deoxyribonucleic acid (DNA) and bacteriophage are reported. Liquid-holding recovery (LHR) is small for the u.v.-sensitive mutant BC100 which, relative to the wild type, also has greatly reduced host-cell reactivation (HCR) of u.v.-inactivated phage, and competent cultures show reduced competent cell reactivation (CCR) of u.v.-inactivated transforming DNA. BC100 cells can be transformed with DNA isolated from the wild type strain Rd to a u.v. resistance similar to that of Rd, and irradiation of the DNA reduces the transformation frequency for this marker (uvr). The u.v.-resistant mutant BC200 displays very little LHR under the usual conditions where reactivation occurs after plating. The colony-forming ability (cfa) of irradiated BC200 is greater than that of Rd, but HCR and CCR are the same on this mutant as on the wild type. The major difference between Rd and BC200 is the enhanced u.v. survival of cfa of the latter. It was determined that this difference reflects cell lysis of irradiated Rd and lack of lysis in BC200 cultures. That lysis is closely correlated with damage to the bacterial chromosome is suggested by the finding that the lytic response of Rd (as determined turbidimetrically) can be negated by the liquid-holding procedure, but lysis of BC100 (which lacks comparable DNA-repair ability) can be only partially inhibited by this procedure. LHR occurs when post-plating dark recovery is incomplete, is temperature-sensitive, and occurs unimpeded when post-u.v. protein synthesis is inhibited by chloramphenicol. It is suggested that enzymatically catalyzed reactivation of DNA occurs or is initiated during liquid-holding of u.v.-irradiated H. influenzae Rd and that the necessary enzyme(s) exists prior to appearance of u.v. lesions in the DNA. Results are reported for X-ray inactivation of transforming DNA as assayed on BC100, Rd and BC200 and of the cfa of the three strains.     

Thermal degradation of copolymers of styrene and acrylonitrile. III. Chain-scission reaction

The chain-scission reaction which occurs in copolymers of styrene and acrylonitrile has been studied at temperatures of 262, 252, and 240°C. Under these conditions volatilization is negligible, and chain scission can be studied in virtual isolation. At 262°C three kinds of chain scission are discernible, namely, at weak links which are associated with styrene units, “normal” scission in styrene segments of the chain and scission associated with the acrylonitrile units. The rate constants for normal scission and scission associated with acrylonitrile units are in the ratio of approximately 1 to 30. The molecular weight of the copolymer has no effect on the rates of scission. At 252°C the same general behavior is observed for the copolymers containing up to 24.9% acrylonitrile. The 33.4% acrylonitrile copolymer is anomalous, however. At 240°C the trends observed at 262°C appear to break down completely although individual experiments are quite reproducible. This behavior at the lower temperatures is believed to be associated with the fact that the melting points of the various copolymers are in this temperature range. Thus the viscosity of the medium, which should be expected to have a strong influence on the chain scission reaction, will be changing rapidly with temperature, copolymer composition, and molecular weight in this temperature range.