Band 28, Heft 1-2

Dioldehydrase (ᴅʟ-1,2-propanediol hydrolase, E. C. 4.2.1.28) apoenzyme exists in an oxidized and a reduced modification due to the presence of disulfide-or sulfhydryl groups in the vicinity of the coenzyme binding site. Both modifications yield active holoenzymes which differ with respect to their sensitivity to O 2 , N 2 O and CO.

-A spartyl-L -alanine an In te rp e p tid e Bridge of the M urein of Bacillus pasteurii M igula H . R a n f t l u n d O . K a n d l e r Murein structure, Bacillus pasteurii The murein (peptidoglycan) of the cell walls of 4 strains of B. pasteurii was analysed. In vegetative cells the peptide subunits consist of L-Ala-N^-D-Glu-L-Lys-D-Ala while the in te r­ peptide bridge bond to the e-am inogroup of L-Lys consists of N-/ff-D-Asp-L-Ala. The spores contain a m urein of the meso-DAP-type. In the strain ATCC 6453 about 30 °/o of L-Ala of the interpeptide bridge is replaced by L-Ser.

A method of quantitative estimation of the contribution of the pentose cycle and the Embden-Meyerhof pathway to erythrocyte carbohydrate metabolism employing [1- 14 C] glucose and [6- 14 C] glucose, is described. It has been found that the ratio of both pathways changes with time of incubation. The contribution of the pentose cycle to glucose metabolism was about 50% and below 10% after 1 hour and 3-5 hour incubation, respectively. Methylene blue (1.84 × 10- 4 м) increased the contribution of the pentose cycle to glucose metabolism from 1.5 times to 7 times after 20 min und 3 hour incubation, respectively. In view of the inhibitory effect of ATP on glucose-6-phosphate dehydrogenase (ᴅ-glucose- 6-phosphate: NADP + oxidoreductase EC 1.1.1.49) the dependence of the contribution of the pentose cycle to glucose metabolism on the length of incubation may be related to the possible changes of erythrocyte ATP content during the separation and washing of these cells.

The inhibition by PBBI of growing Candida albicans was studied; additional information was obtained from the analysis of regeneration. The type of the growth inhibition depended on the cell suspension. At more than 10 7 cells per ml, the inhibition was transient; the inhibitor was taken up rapidly by the cells to a limit of 37 nmoles per mg dry wet. At higher doses, the growth was inhibited permanently, and then, and only then, a lethal effect was observed. At sublethal doses of the inhibitor, the following effects were observed: Inhibition of respiration without apprecciable .change in R.Q., of incorporation of labelled precursors into proteins and nucleic acids, and of eight of fourteen enzymes studied; the level of total free thiol groups was lowered; and a cross- over between hexose monophosphates and fructose diphosphate was induced. The original activities of the enzymes and metabolic processes inhibited were restored coincidentally with the reappearance of growth of the cells. Inhibition of G-6-PDH, PFK and of an early step in the oxidation of NAD(P)H appeared to be determinative for the growth. In the cells inhibited transiently by iodocetate, GAPDH and ADH were the most sensitive enzymes. The activity of the latter but not of the former was readily restored. The R.Q. was lowered, and was restored later than growth. The cells which recovered from the inhibition by iodoacetate appeared to be physiologically different from the control.

The presence of 20 flavonoids has been detected in herbs of Larrea tridentata. Six pigments were isolated and characterized by chromatographic and spectrophotometric methods (shifts with several reagents), acid hydrolytic and alkaline cleavage and finally by comparison with authentic samples. The structure of this compounds has been established as: quercetin-3-rhamnoglucoside, quercetin-3-glucoside, kaempferol-3-methyl ether, quercetin-3 1 -methyl ether, kaempferol and quercetin.

An antiserum to lutein inhibits photosynthetic electron transport between water and potassium ferricyanide in diloroplasts from green Nicotiana tabacum var. John William’s Breadleaf. However, electron transport between diphenylcarbazide and potassium ferricyanide is not impaired. From this it is concluded that the photochemically active carotenoid should feed its electrons into the photosynthetic electron transport chain before the site from which diphenyl-carbazide donates electrons. The inhibition of the ferricyanide Hill reaction in diloroplasts by antibodies to lutein depends on the accessibility of the carotenoid antigen in the thylakoid membrane. In fresh preparations the accessibility is greater in diloroplasts in which photo- synthetic electron transport is coupled to photophosphorylation. Concomitantly the antiserum to lutein agglutinates only such chloroplast preparations in which the Hill reaction is impaired by the antiserum. An antiserum to plastoquinone inhibits ferricyanide photoreduction of diloroplasts regardless whether driven by water or diphenylcarbazide as the electron donors. Typical photosystem-I-reactions are not influenced by the antiserum. In a certain type of chloroplast preparations the antiserum does not inhibit PMS-mediated photophosphorylation inferring that plastoquinone, eventually involved in this reaction, is either not accessible to antibodies, or that this cyclic electron flow does not necessarily pass through plastoquinone.

The activities of enzymes related with chlorophyll and porphyrin synthesis have been examined during development and greening of young corn leaves. The enzymes succinyl-CoA-synthetase (SCoAS), δ-amino-levulinate synthetase (ALAS), δ-amino-levulinate dehydratase (ALAD) and the enzymes involved in porphobilinogenase (PBGA) were under investigaton. When leaves are illuminated and chlorophyll synthesis begins the activity of ALAD is not influenced. The activity of PBGA and SCoAS are slightly higher than in darkness, but the changes are below the range affecting chlorophyll biosynthesis. ALA, however, is only synthetized in the light. Synthesis ceases immediately when illuminiation ist stopped, indicating'that in darkness ALAS is not active. On the other hand ALAS is active in dark grown roots, tubers and other non-leaf tissues. Feeding the plant with succinate, glycine or α-keto-glutarate has no effect on chlorophyll synthesis, but the amount of ALA is reduced, whereas sucrose promotes its accumulation. The results are discussed with completely antitethaal results obtained with tissue cultures of tobacco and are integrated into a scheme which excludes the contrariety of hypotheses deduced from experi- ments with inhibitors of protein and nucleic acid synthesis. It is suggested that the varying results are caused by the action of light on different stages in differentiation of plastids and cells. In contrast to the enzymes SCoAS, ALAD and PBGA whose activities were determined in vitro, ALAS was assayed in vivo by means of the accumulation of (5-amino-levulinate (ALA) after blocking the enzyme ALAD by levulinate (LA). Optimum accumulation is observed when the concentration is about 2 · 10 -2 м. LA is not converted to ALA in appreciable amounts. This could be proved by feeding the plants with 14 C-LA which was prepared from uniformly labeled 14 C-fructose.

The frequency dependence of the proton spin relaxation in muscle tissue shows that the mobility of the muscle water must be described by a continuous distribution of jumping times instead of the usually assumed two-phase model. Measurements on frog muscles (rana esculenta and rana pipiens, gastrocnemius) in the Larmor frequency range 3 kHz to 75 MHz can be understood quantitatively by a log-gaussian distribution, which supports a close relation to protein solutions.

Fragments of the thylakoid membrane, obtained by ultrasonication of stroma-freed chloroplasts and subsequent fractioning centrifugation, aggregate in buffer solutions of suitable ionic strength in the pH-range of 6.0-8.5. This aggregation leads to the formation of vesicles and membranes, which may reach a size of up to 0.5 mm. A suspension of the fragments, having an average diameter of 100 Å, is stable in water. A protein preparation, obtained by treatment of stroma-freed diloroplasts with sodium deoxycholate and subsequent gel filtration, contains 4 % chlorophyll but no detectable amounts of colourless chloroplast lipids, nor deoxycholate. This preparation aggregates in the pH-range of 6.0-7.0 equally to membranes and vesicle-like structures. The solution of this protein, exhibiting a molecular weight of 600 000, is stable in water. The proteins of both preparations are not denatured and both preparations exhibit photochemical reactions.

Free and membrane-bound ribosomes were isolated from rat liver and quantitized by photometric methods. The amount of membrane-bound ribosomes remaines relatively constant over 24 hours whereas the amount of free ribosomes changes considerably: a maximum appears between 6-9 h, a minimum between 18-21 h. Fasting the animals increases the overall variance. Injections of cortisol 4 hours before killing the animals increases the total amount of ribosomes and induces a definite maximum of membrane-bound ribosomes at 6 h. The maximum of free ribosomes appears at the same time as in control animals. In contrast to cortisol, corticosterone has no effect on the total amount of ribosomes, it induces, however, a maximum of membrane-binding between 18-21 h. Also in this case the maximum of free ribosomes remains unchanged. In the evening, the protein content of free ribosomes decreases whereas a change was not observed in membrane-bound ribosomes. Cortisol increases the protein content in free and membrane- bound ribosomes.

Intraperitoneal injections of 2 mg or 5 mg cycloheximide per 100 g body weight into male Sprague-Dawley rats, 3 months old, induce a doubling of the amount of membrane-bound ribosomes after 1 hour. After 2-3 hours the control value is readied and a slow decrease in the number of bound ribosomes can be observed thereafter. The concentration of free ribosomes decreases very markedly during the first hour after injection and more slowly during the following time. Injections of cycloheximide (5 mg / 100 g; 20 min before sacrifice) at different times of day result in a bimodal curve of bound ribosomes with maxima at 9-12 h and 21 h, the maxima of free ribosomes appears at the same time as the maximum of the controls (9-12 h). Analysing the amount of bound ribosomes 3 hours after the injection of cycloheximide a bimodal rhythm can also be observed, the latter curve, however, is phaseshifted for 3-6 hours and appears at a lower level. No rhythm can be detected in the free ribosomal fraction after this treatment. Administration of cycloheximide causes a decrease in protein content of both free and bound ribosomes.

The uropygial gland fat from the jackdaw, the carrion and the hooded crow are shown to be ester waxes. Chemotaxonomically the latter two are undiscernible. Their uropygial waxes consist of 4- and 6-monomethyl-, 4.6-, 4.8-, and 4.10-dimethyl- and 4.6.10- and 4.6.12-trimethyl- substituted fatty acids and n- (59.7%) as well as monomethyl-branched alkanols with branches in 4-, 6-, 10-, and 14-position. In contrast to the jackdaw they show no relation to the earlier investigated rook. The uropygial gland fat from the jackdaw is composed of n- (35.7%) and 2-methyl-substituted fatty acids (64.3%) and w-(87.5%) and 2 methyl-substituted alkanols (12,5).

The uropygial gland fats from the razorbill, guillemot (two varieties) and the black guillemot arc very complex mixtures of ester waxes. Among the wax acids n- octanoic acid dominates followed by homologous series of 2-, 4- and 6-monomethyl-, 2,6-, 2,8-, 2,10-, 4,6-, 4,8-, 4,10-, 4,12-dimethyl- and 2,4,8-, 2,6,10-, 2,6,12-, 4,6,10- and 4,8,12-trimethyl-substituted fatty acids. The alcoholic components consist of n-, 2-, 4-, 6-, 8- and 12-monomethyl- as well as 2,6-, 2,8-, 2,10-, 4,6-, 4,8-, 4,10- and 4,12-dimethyl - branched alkanols. The black guillemot differs from the other species investigated by the occurence of fatty acids which have the first branch in 2- while the others start with the 4-position. The chemotaxonomy of the 20th order of the natural system is discussed.

The reaction of bacteriophage T4 with 1-fluoro-2,4-dinitrobenzene resulted in a covalent binding of 2,4-dinitrophenyl (DNP) determinants to the phage. From the kinetics of inactivation reflecting the coupling process it is concluded that attachment of more than one DNP group to the critical site(s) of the phage is required for inactivation (multi-hit reaction). Contrary to this the neutralization of DNP-T4 by anti-DNP antibody turned out to be a first order reaction, until 80 %> neutralization fitting one-hit kinetics. If compared with native T4, the susceptibility of DNP-T4 to neutralization by anti-T4 antibody is considerably higher, indicating that attachment of DNP groups to T4 amplifies the sensitivity to neutralization by anti-T4. Comparing neutralization kinetics of DNP-T4 and native T4 by anti-DNP-T4 antibody it is suggested that native determinants and DNP groups, as well as determinants resulting from alteration due to the coupling process, all together may contribute as targets for neutralization. Three characteristics strengthen the view that the velocity of T4 conjugates in infecting the host strain is markedly decreased if compared with that of native T4: (a) considerable discrepancy between direct plating and decision technique (b) increasing variety of plaque size and (c) decreased velocity of the first step of reproduction. The kinetics of neutralization observed can be reconciled with a model proposed by Krummel and Uhr. The kinetics of reactivation of neutralized DNP-T4 by the presence cf DNP-BSA has been investigated and the problems involved in the reaction are discussed.

The lipid composition of the Flury HEP strain of rabies virus grown in BHK 21/C 13 cells was determined. The dried purified virus preparation contains 5.5 % neutral and 19.5 % polar lipids. Cholesterol was found to be the major neutral lipid. Phopholipids constitute 11.2 %; and glycolipids represent 4.6 % of the virus mass. The residual 3.7 % of extracted polar lipid material could not be accounted for by any known lipids. Phosphatidylethanolamine, phosphatidylcholine and sphingomyelin are the main constituents of the viral phospholipids. Hema- toside is the only ganglioside and the main glycolipid present in the virus. The glycolipids of the host cell and the virus are identical. The molar ratio of sphingolipids to glycerophospho-lipids is 0.8.