Volume 26, Issue 4

The salts of Fe III , Co II , and Ni III form precipitates with Na 4 - or K 4 [Fe II (CN) 6 ], the so-called mixed hexacyanoferrates (II) (HCF). Experiments with radioactive tracers ( 24 Na, 42 K, 59 Fe III , 60 Co II , 59 Fe II (CN), 4⊖ , and 204 Tl I ) have shown that the composition of HCF depends on the nature as well as on the initial concentration of the metal ions involved and can be described by the general formula ExMzR·n E Y. Ε stands for univalent cations (e.g. H ⨁ , Na ⨁ , K ⨁ , Tl ⨁ , and others more), M for a heavy metal ion, R for Fe(CN) 6 4⊖ , and Y for anions (e. g. Cl ⊖ , SO 4 2⊖ , OH®). The mixed HCF are cation- and anion-exchangers, the equilibrium between solid and liquid phase depending on the nature and concentration of cations and anions in both phases. The binding stability of cations increases proportionally to the effective ionic radius: H ⊕ <Na ⊕ <K ⊕ <Tl ⊕ . Because of its favourable ionic radius, Tl ⊕ exhibits a high affinity towards the mixed HCF and can be separated from solution with a high efficiency.

Solvent effects of 31 P nuclear magnetic resonance of white phosphorus in n-paraffins, substituted and cyclic paraffins, as well as in benzene, and some amines are discussed. The largest chemical shifts were caused on the one hand by dispersion interactions of dissolved phosphorus and solvent molecules and on the other hand by interaction of different phosphorus molecules; the latter influence may shift the resonance signal of white phosphorus about 35 ppm towards higher field relative to solid white phosphorus. Specific interactions between dissolved phosphorus and halogen atoms increased in the series Cl, Br, I. Phosphorus acted as an electron donor. Electron acceptor properties in amines as solvents were not found. Shifts towards lower field in the order of magnitude of 1 ppm were caused by highly polar solvents (Stark effect). By comparing dilute solutions of phosphorus in 1,3-cyclohexadiene and benzene, respectively, the influence of the diamagnetic anisotropy on the resonance of phosphorus could be estimated to result in a shift of about 1 ppm towards higher field, whereby the different dispersion interactions, were taken into account.

It is shown that in the case of metals connected by a first order conductor the decomposition of formic acid is less at the element of lower work function while it is more at the element of higher work function. The metals used were Ni, Cd, Zn. The results correspond to the investigations of other authors 1 who showed that the activation energy on alloys depends on how far the concentration of electrons is from full saturation of the lattice type. This effect is explicable in terms of the development of a contact potential, the conditions in the case of metals being similar to those in the case of alloys.

With barium hydrazide, which is easily to prepare and relatively harmless to handle, some addition-, substitution- and reduction-reactions were carried out. Partially we could get the same, partially however other products than by the analogous reactions with the normally used, but highly explosive sodium hydrazide. Especially the formation of the azo-compound H 5 C 6 -CH 2 -CH 2 -N = N-CH 2 -CH 2 -C 6 H 5 and of H 5 C 6 -C(NH)-NH-NH-C(NH)-C 6 H 5 by the addition of barium hydrazide to styrene resp. benzoic nitrile was remarkable.

The kinetics of the formation and dissociation of Ni- (II) -complexes of glutarate, 2-hydroxyglutarate, and 3-hydroxyglutarate were investigated by a pressure jump method. The sequence of the steps in the chelation process for the ligands 2- and 3-hydroxyglutarate, respectively, were evaluated and the rate constants for the specific steps were determined. The results show the chelation to start with formation of a Ni-carboxylate bond and to end with the coordination of the hydroxyl group. In both systems the rate determining step in the chelation process is the ring closure and not the formation of the first bond.

The X-ray determination (W. HOPPE and coworkers) of the structure of the Rh-complex from tris- [triphenylphosphin] -rhodiumchloride and 1.2-bis- [phenylpropinoyl] -benzene (synthesized by E. MÜLLER and coworkers) shows a molecular structure with a metallocyclopentadiene system formed by both C≡C groups and the Rh atom by ring closure. The coordination number of rhodium is 5. The reaction path leading to the complex is discussed, and it is pointed out that the complex does not reacting with typical dienophiles but with acetylenes.

γ-radiolysis of 5-bromo-2-deoxyuridine in neutral oxygen saturated aqueous solutions leads to the folowing products: hydrogen bromide, hydrogen peroxide, organic peroxides, isodialuric acid deoxyriboside, deoxyuridine, deoxyribosylurea, urea, deoxyribose and 5-bromouracil. In addition some unidentified products are formed. The main products are isodialuric acid deoxyriboside and hydrogen bromide.

In the γ-radiolysis of 5-bromodeoxyuridine (BUdR) in neutral aqueous O 2 -saturated solution OH radicals react both with the base and the sugar moiety of BUdR to an approx. equal amount. At low BUdR concentrations solvated electrons (e ⊖ ) and H radicals are scavenged by O 2 . At high BUdR concentrations e ⊖ and H radicals react with BUdR. These two species preferentially react with the base, Br® and isodialuric acid deoxyriboside being the major products. Similarities with the γ-radiolysis of 5-bromouracil are discussed.

Basic dimethyl-arylmethylene-sulfonium resins (L. C. DORMAN and J. LOVE, J. org. Chemistry 34, 158 [1969] have been used as reactive supports for the covalent binding of N-protected as well as N-unprotected peptides through a benzyl ester linkage. Example are given of effective coupling of peptides of rather long sequence, the quantity of peptide linked being up to 0.5 μmole per mg of resin. The method could find practical use in the solid state degradation of polypeptides.

The oxidation of methyl n-propyl ketone by Mn (III) sulphate in aqueous acetic acid is first order with respect to the ketone and Mn (III). The rate independent of acidity and solvent composition. Added Mn (II) does not alter the rate. The activation parameters for the oxidation and enolisation reactions were evaluated. The oxidation is faster than the enolisation under similar conditions. A mechanism involving an attack on the keto-form by Mn (III) sulphate complex is proposed.

Monosodium derivatives of acetoacetanilide and benzoylacetanilide are synthesized and characterized. The effect of conjugate chelation on carbonyl stretching frequency has been studied by comparing the infrared and ultraviolet spectra of acetoacetanilide and benzoylacetanilide, and their monosodium derivatives. Ultraviolet spectra suggest structural differences between the monosodium derivatives and the corresponding enolates.

Aliphatic compounds are hydroxylated to the corresponding isomeric alcohols by an unspecific hydroxylation system in the endoplasmic reticulum of the liver cell. As models for this reaction the following hydroxylation systems were investigated: 1. trifluoroperacetic acid, 2. the photolysis of 2,2-dimethylquinoxaline-di-N-oxide and 3. the system Fe 2⊖ /2-mercaptobenzoic acid/O 2 . 2-Methylbutane, methylcyclohexane and n-pentane are hydroxylated by a selective mechanism probably involving an oxenoid species. The pattern of isomeric alcohols closely resembles that obtained of rat liver microsomes indicating a hydroxylation mechanism of similar selectivity. From comparison with the nonenzymatic systems it is possible to conclude on minor steric effects in the microsomal hydroxylation of these alkanes.

A “latent” ribosomal ribonuclease was demonstrated in Saccharomyces cerevisiae which was repressed by glucose parallel to the respiratory enzymes during logarithmic growth. It was induced by oxygen after consumption of glucose, and while the cells were growing on ethanol. In the growing cell, this ribonuclease was associated with the ribosomes. It hydrolyzed non-functional polynucleotide bonds only leaving untouched the integrity and functionality of the ribosomal structure. Though this ribonuclease was not integrated into the mitochondria, its synthesis depended upon the intact and coupled respiratory chain, similar to the mitochondrial enzymes proper. The function of the ribosomal ribonuclease seems to be the adaptation of the ribosomal ribonucleic acid content to the specific growth conditions together with the protein synthesis capacity of the cell. Hence, the enzyme serves the economy of the cell: when the cells grow fast during the fermentative phase only little ribonucleic acid is degraded; during the oxidative phase, when metabolic activity is low, ribonucleic acid is hydrolzyed as a saving mechanism. The switching between glycolytic and aerobic metabolism, which is brought about by alternating synthesis of the respective enzymes, is closely related to the ribonucleic acid turnover in the yeast cell and is probably regulated analogously in higher organisms.

Helveticone, the characteristic pigment from Chroogomphus helvetivus and Ch. rutilus sporophores has been identified as 2,4-Dihydroxy-3-farnesyl-1,4-benzoquinone (1). Minor pigments are bovine (2) and xerocomic acid, already known from the Boletaceae.

A compound which plays an important role in the stimulation of oviposition in the carrot rust fly was isolated from carrot leaves. The active component has been identified as trans-1,2-dimethoxy-4-propenyl-benzene (methyl-iso-eugenol).

Dibromothymoquinone and its hydroquinone are inhibitors of non cyclic electron flow from water to NADP, anthraquinone or methylviologen. The inhibition is competetively reversed by plastoquinone. It appears that dibromothymoquinone is an antagonist of plastoquinone and that it prevents the enzymic (by the next endogenous carrier of the chloroplast electron transport chain) but not the chemical (by ferricyanide) reoxidation of reduced plastoquinone. This follows from the result that the photoreduction of ferricyanide and DCPIP * is not inhibited by dibromothymoquinone in sonicated chloroplasts and is inhibited in intact chloroplasts to only 60% or 80% respectively. It is concluded that dibromothymoquinone does not inhibit photoreductions by photosystem II. According to their response to dibromothymoquinone, cyclic photophosphorylations can be subdivided in those requiring plastoquinone and those which do not. Menadione catalyzed cyclic photophosphorylation is inhibited by dibromothymoquinone, whereas the PMS catalyzed system is not. The DAD cyclic system is only partly inhibited by dibromothymoquinone. The PMS catalyzed cyclic photophosphorylation in the presence of dibromothymoquinone is antimycin sensitive, which suggests that the PMS system can switch from a plastoquinone dependent system to a plastoquinone independent, but cytochrome b dependent system, which is now antimycin sensitive. Ferredoxin catalyzed cyclic photophosphorylation is inhibited by dibromothymoquinone as well as by antimycin. The data indicate that non cyclic electron flow through both photosystems is obligatory dependent on plastoquinone, whereas cyclic systems do not necessarily include plastoquinone. The relevance of the results to the possibility of different coupling sites in cyclic and non cyclic electron flow systems is discussed.

Absorption changes indicating the metarhodopsin I -II reaction and rapid pH-changes are measured as a function of pH in isolated bovine rod outer segments (ROS), using a rapid registrating flash photometer. An alkalization of the ROS-containing solution is observed which runs parallel to the metarhodopsin I -II reaction. In this process dissociable groups with pK-values at pH 6.3 and 10.5 are involved.

The dark adapted rhabdom is surrounded lengthwise by a wide margin of large vacuoles (“palisades”). The pigment granula within the retinula cells are uniformly distributed in the plasma outside of the palisades. Illumination of the eye with white light from a xenon-arc (15 · 10 -4 cal/cm 2 · min) caused the pigment granula in the retinula cells to wander distally and to accumulate close to the rhabdom. The vacuole margin remained more proximal but was separated from the rhabdom by a wider plasma zone. After long-time illumination (30 min) the long pigment-cells expanded while the retinula cells simultaneously became thinner. Reference is made to the functional significance of these variations.

Growth-inhibition of GW-77 human colonic tumors growing in hamster cheek pouches was found to be proportional to the duration of heating the exposed tumors by 4 °C with short-wave diathermy. A maximal tumor growth-inhibition of 35 per cent resulted from administration of a daily 30 min. heating period repeated on 7 consecutive days. Further, hyperthermia to the left cheek pouch tumors resulted in growth-inhibition of the contralateral, presumably normothermic, cheek pouch tumors, thus causing us to question whether hyperthermia has abscopal antitumor effects.