Volume 26, Issue 5

The kinetics of chromic acid oxidation of propanaldehyde, butyraldehyde and isobutyraldehyde in aq. acetic acid have been studied. The product of the oxidation is the corresponding carboxylic acid. The reaction is of first order with respect to each the acid chromate ion, HCrO 4 ⊖ , and the aldehyde but of second order to hydrogen ion. The rate increases with proportion of acetic acid in the solution. The activation parameters for the oxidation and enolisation reactions have been evaluated. The rate of enolisation under similar condition is less than that of oxidation. A mechanism in which the first step is the rapid reversible formation of a chromate ester followed by a hydrideion transfer in the rate determining step has been suggested.

A simple procedure for the preparation of S-alkyl phosphorothioic acids (1) involving triethylammonium di-t-butyl phosphorothioate (2) as a thiophosphorylating agent for organic halides has been devised.

Clostridium kluyveri ferments crotonate in D 2 O or H 2 O/ΗΤΟ and forms [2,3-H] (2R,3R) -butyrate. This was chemically converted to [1,2-H] * (1R,2R) -propylamine, [2-H] (2R) -propylamine, [2-H] (2R) -propionate and [1-H] (1R) -ethylamine. ORD curves of the deuterated compounds have been measured. C. kluyveri ferments also other α,β-enoyl compounds and shows exchange reactions with butyrate homologues and derivatives.

The intramolecular alkylation of haloamides 18 where there is similar opportunity for formation of four member as well as of six member rings, leads to the formation of β-lactams rather than that of six member rings. The study further shows that when the activity on the methyne hydrogen is simultaneously afforded by an aliphatic carbonyl and phenyl substituents, cyclisation can be effected by the weak base triethylamine. The paper records the synthesis of two unique dumbell shaped β-lactams 19.

SCFMO study of the tautomerism of anilino-thiazole, anilino-oxazole, and anilino-oxadiazole shows that amino form predominates.

The effect of a semisynthetic pentosan-polysulfo-ester (SP 54) upon the complement system in vitro has been studied in comparison with the effects of heparin. Both substances inhibit in small concentrations the Cl-esterase. There are differences in the effect of SP 54 and heparin. According to the in vitro results SP 54 seems to have a ten times higher anticomplementary action. At the same time the influence upon coagulation is less. SP 54 appears to be a substance of therapeutic interest.

A number of independent systems for sugar transport in Neurospora have been postulated. An approach to identification of specific components of the sorbose transport system in ungerminated conidia pretreated with sorbose is described here. The fact that sorbose stimulates sorbose-uptake without causing germination was exploited in differential labeling experiments. Sorbose treated and untreated conidia were incubated with ( 3 H) -leucine and ( 14 C) -leucine respectively, and then mixed extracts fractionated on CM-cellulose at pH 4.75. Changes in the 3 H/ 14 C-ratio indicated sorbose-induced or -repressed substances. In selecting labeling conditions, care was taken to avoid errors that might arise from any differences in the internal amino acid pool size. The investigation revealed a buffer-soluble component repressed by sorbose and a Triton-soluble component induced by sorbose. The buffer-soluble, sorbose repressible protein is discussed in connection with the phenomenon of sorbose toxicity in Neurospora. The Triton-soluble, sorbose stimulated component, probably of carotenoid nature, is considered as a possible constituent of the sorbose transport system investigated here.

It is shown that the 1700 × g supernatant of human lymphocytes stimulated with phytohaemagglutinin had an inhibitory, but not a lytic, effect on the permanent tissue sulture cell strain of Fl-cells. The factor called proliferation inhibition factor seems to be a protein. The incorporation of H 3 -thymidin into DNA was affected more and earlier than the incorporation of H 3 -uridin into RNA or C 14 -Leucin into protein of the cultured cells. There was no effect on respiration or glycolysis.

The hypothesis of cancerostatic activity of deoxycholic acid, recently outlined, is supported by correlation of natural cancer resistance with the level of deoxycholic acid in animals and humans. Analyses of sera indicate lower levels of unconjugated deoxycholic acid in cancer patients, the mean values of other bile acids being normal. Application of this theory to statistics of cancer incidence reveals possibilities of new aspects.

Germinating soybeans, when incubated for 20-30 hours under an illumination at 25°-30° temp, with labeled 32 P-phosphate, 14 C-acetate, 14 C-glycerol and 14 C-choline, radioactivity ranging from 2 to 14% is incorporated into the main phosphatides lecithin (PC), phosphatidylethanolamine (PE) and monophosphoinositide (MPI). The incorporation of 32 P-phosphate in these phosphatides depending on light and temperature, increases to its maximum (3.7 mCi/1 g soybeans) almost running linear and continues further even in the absence of any further germination due to intensive exposure to radiation. 14 C-acetate is incorporated almost exclusively into fatty acids of the phospholipids during germination as a result of which highest specific radioactivity was seen in the stearic acid followed by oleic acid and palmitic acid. Linol- and linolenic acid under these experimental conditions are weakly or not labeled, 14 C-choline is incorporated only in PC. As the PC after 14 C-(methyl) -methionine-incubation does not exhibit any significant labeling, one can exclude the pathway of PC-biosynthesis through PE-methylation. The utilization of 14 C-glycerol proves that the incorporation of all the compounds under consideration here is effected not by a mere exchange but by a de novo synthesis. This procedure of labeling is suitable for preparing 3 H-, 14 C- and 32 P-PC, -PE, -MPI and phosphatidic acid (PA).

Antibodies to chlorophyll are specifically adsorbed onto the membrane surface of thylakoids. The antibodies inhibit photosynthetic electron flow from water to NADP ⊕ . This inhibition is presumably caused by adsorption of the antibodies onto the centre chlorophyll of light reaction II. Fragments of the thylakoid membrane, obtained by ultrasonication and subsequent fractioning centrifugation, exhibit only photosystem-I activity. Conversely, the specific adsorption of antibodies to sensitizer chlorophyll has no inhibitory effect on electron transport. The ferricyanide Hill reaction of chloroplast preparations is inhibited by chlorophyll antibodies. From these observations it is concluded that the centre chlorophyll of light reaction II and at least part of the sensitizer chlorophyll is located on the surface of the thylakoids. As agglutination is sterically inhibited by the membrane protein, it is assumed that the chlorophyll is located in gaps or pores of the protein layer. Two fractions of the lamellar system exhibit photosystem I activity of different characteristic electron donor specificity. These fractions can be further distinguished in terms of their circular dichroism and protein composition.

By means of a new parameter “t” characterizing the time course of osmotic haemolysis registered spectrophotometrically it has been described more comprehensively the membrane stabilizing effect of biological active substances. Extent and time course of osmotic haemolysis can be varied after the influence of any stabilizing drugs in different patterns. Both substances, IMET 3393 (γ-[1-methyl-5-bis- (β-chloraethyl) -amino-benzimidazol- (2)] -butyric acid · HCl) and IMET 3164 (β- [1-phenyl-5-bis- (β-chloraethyl) -amino-benzimidazolyl- (2)] -DL-alanine), respectively, i.p. applicated have increased the osmotic resistance and have delayed also the haemolysis of red blood cells in mice. The method was proved in vitro by chlorpromazine. This agent, however, has alterated only the resistance of erythrocytes but the parameter “t” was not influenced.

Preparation of derivatives of peptide antibiotics polymyxin B and colistin- substituted on free amino groups by aminoacyl residues is described. The first procedure is based on the condensation of the antibiotic with active ester of a suitably protected amino acid. The second one makes use of Woodward’s reagent by condensation of the antibiotic with a protected amino acid. The following compounds were prepared: glycyl- 14 C-polymyxin B and glutaminyl-polymyxin B and glycylcolistin, also under conditions suitable for a radioactive synthesis. All the preparations preserve a substantial part of the biological activity comparable with polymyxin B and colistin.

The concentration dependence of the dielectric dispersion between 100 kHz and 15 MHz has been investigated for separated α and β chains of human hemoglobin. It is shown that such dielectric measurements can give very detailed information on aggregation phenomena. Specific dielectric increments and dipole moments of monomeric and aggregated chains could be obtained.

The mass response of the photoreceptor cells of the isolated crayfish-retina (Astacus leptodactylus) (receptor potential ReP) resulting from short and long light stimuli, has been measured with external electrodes. The ionic composition of the saline by which the preparation was perfused was changed and the influence of those changes on the ReP was measured under constant stimulus conditions. When all sodium ions are substituted by potassium ions, the height of the ReP is reversibly both decreased and shortened (Figs. 3 and 4). When all sodium ions are almost substituted by choline ions, (the remaining sodium concentration at the photoreceptor cells being less than 1 mMol/Z) the sensitivity to light adaptation is drastically and reversibly increased. Mainly due to light adaptation the ReP becomes smaller and shorter whereas the latency period increases (Figs. 5 - 8). If the concentration of extracellular calcium is reduced to less than 0.1 mMol/l, the decrease of the REP is considerably and reversibly slowed down while the increase of the REP remains almost unchanged (Fig. 9). If magnesium ions are also lacking the effect is even more pronounced (Figs. 10 and 11). All these changes of the ReP are probably due to actions of the ions on the membrane of the photoreceptor cells or its immediate vicinity. The results do not allow an unequivocal decision whether the ReP is due to an increased conductance (CIM) of the photoreceptor cell membrane or due to a change in the action of an electrogenic ion pump (EPM). But considering the results as a whole, and especially those from the low Ca- and low Mg-experiments, it seems unlikely that the ReP is caused by an EPM.

A model system consisting of oil droplets in a glycerol-water matrix was freeze-cleaved and subjected to prolonged treatment with diethyl-ether at dry ice temperature before etching and shadowing. Dissolution of droplets became visible after some hours. Complete fat extraction resulted in a uniform appearance of the replica with holes replacing the droplets. Possibilities of this new method for the demonstration of membrane lipids in vitrified cells are discussed.