Volume 19, Issue 12

The kinetic data of the hydrolysis of some serine peptides in diluted hydrochloric acid and in pure water and of the rearrangement of O-glycyl-DL-serine to glycyl-DL-serine were determined. The hydrolysis of glycyl-DL-serine and DL-alanyl-DL-serine proceeds surprisingly rapidly in pure water as compared with the hydrolysis of those peptides in 0.5 N hydrochloric acid as well as the hydrolysis of glycyl-DL-alanine in purely aqueous solution. The O → N migration of the glycyl residue in O-glycyl-DL-serine which probably is an intermediate in the cleavage of glycyl-DL-serine in purely aqueous solution represents a three center reaction in which the nucleophilic attack on the O-peptide and peptide bond, respectively, involves a free basic amino group. The analogy between the serine peptide interconversion and the hydrolysis catalyzed by certain proteolytic enzymes is referred to. Under the conditions of freeze drying are formed in hydrochloric acid solutions of DL-alanyl-DL-serine O-peptide and depsipeptide.

Lewis acid phosphorus fluorides, such as C 6 H 5 PF 4 and (C 6 H 5 ) 2 PF 3 , react with hexamethyl-disilazane to give polymeric iminophenyl-phosphonic- or -phosphinic fluorides, which can be dehydrofluorinated to phosphonitrilic type products.

The biosynthesis of gentisine (I) in Gentiana lutea involves condensation of a C 6 - C 1 acid with three acetate units, which form the phloroglucinol ring. Nature and origin of the C 6 -C 1 acid are discussed.

Using 15 N it is shown that 91% of the nitrogen of the alkaloid gentianine isolated from Gentiana lutea originates from the ammonia added during the isolation. Gentianine thus is mainly an artifact which, according to chromatographic evidence, is formed from gentiopicroside. These findings are extended to other Gentiana species by chromatographic techniques. The biosynthesis of gentiopicroside is discussed and some evidence against an acetate pathway and for a mevalonate pathway is presented.

Phloroglucinol- [2.4.6- 14 C 3 ] was synthesized from ethyl malonate- [2- 14 C] and condensed with p-carbethoxycoumaryl chloride; the resulting product was saponified to form 5.7.4'-trihydroxyflavanone- [6.8.10- 14 C 3 ] (II). The latter compound was mixed with 5.7.4′-trihydroxyflavanone-[2- 14 C] to yield the desired 5.7.4'-trihydroxyflavanone-[2.6.8.10- 14 C 4 ] (III). Administration of a sample of III in which the activity ratio ring A/C-2 was 1: 2.04 to red cabbage seedlings led to a cyanidin with an activity ratio ring A/C-2 of 1: 2, as was shown by degradation of the cyanidin to phloroglucinol and protocatechuic acid. This result proves that III is incorporated intact into cyanidin. After administration of III to chana germ (Cicer arietinum) Biochanin A (5.7-dihydroxy-4′-methoxyisoflavone) with an activity ratio of 1:2.24 was obtained. In contrast, there was only a small amount of incorporation of III into formononetin (7-hydroxy-4'-methoxyisoflavone), and the activity ratio fell to 1 : 7. These results prove the intact and specific incorporation of III into Biochanin A. When II is fed to Cicer arietinum about 3% of the total activity is found in the respiratory carbon dioxide after 48 hours. From this observation it can be concluded that the plant is able to degrade ring A of II.

Both 4.2′.4′.6′-tetrahydroxychalcone-2′ - glucoside-[β- 14 C] (I) and 4.2′.4′-trihydroxychalcone-4′. glucoside-[β- 14 C] (II) are converted into cyanidin-[2- 14 C] in red cabbage seedlings, even though chalcone II does not possess the phloroglucinol-type pattern of substitution in ring A. Therefore the possibility that the incorporation of the chalcones proceeds via a degradation to p-coumaric acid was considered. After administration of II to red cabbage seedlings p-coumaric acid- [β- 14 C] could be isolated by means of dilution analysis, the location of the radioactivity being proved by degradation of the p-coumaric acid. After administration of I to Petunia hybrida radioactive p-coumaric acid and ferulic acid were isolated from the shoots and blossoms. It can be deduced from these results that the plants are able to split chalcones I and II - or the corresponding flavanones - between the carbonyl group and ring A.

Bei Komplement-fixierenden Immunreaktionen wird Lysolecithin vermehrt gebildet 1, 1a . Die gesteigerte Lysolecithinbildung läßt sich in Seren des Menschen, bei Meerschweinchen, Ratten, Kaninchen und Schweinen nachweisen 2-4 . Hieraus haben wir den Schluß gezogen, daß Lysolecithin ein Endprodukt der Komplement (C′) -Reaktion ist, und es entsteht die Frage, ob dem so freigesetzten Lysolecithin biologische Bedeutung, z. B. als Cytolysin zukommt. Lysolecithin ist bekanntlich noch in sehr kleinen Konzentrationen hoch grenzflächenaktiv, so daß an Orten seiner Bildung mit aktivierenden oder schädigenden Wirkungen an Zellgrenzflächen zu rechnen ist. Wir haben u. a. die Wirkungen sehr kleiner Lysolecithin-Konzentrationen aus Peritoneal-Makrophagen der Maus in vitro und in vivo untersucht. Dies lag insofern nahe, als STUART 5 und COOPER 6 kürzlich über die teils stimulierende, teils hemmende Wirkung von Lipoiden (synthetische Triglyceride) auf die Phagocytose von Makrophagen berichtet haben *. Unter biologischen Bedingungen sind bei optimaler Phagocytose Antikörper und Komplement beteiligt. Es zeigte sich nun tatsächlich, daß die Phagocytose durch kleinste Mengen von Lysolecithin (LL) in markanter Weise beeinflußt wird.

Ribosomal ribonucleic acid (rRNA) from rat liver has been investigated as to the stability of its secondary structure, using UV hyperchromism under heating at different ion conditions of the solvent. The T m value is directly related to log [H®] within p H 5 -8 and at p H 7 to log µ of monovalent cations. In presence of monovalent cations (Li ⊕ , K ⊕ ) an inverse relation exists between ion radius and T m value, while the T m is directly related to the ion radius of bivalent cations (Mg 2⊕ , Ba 2⊕ ). Bivalent cations are more effective in stabilizing the secondary structure than monovalent ones of the same strength and radius. rRNA from rat hepatomas has a more stabile secondary structure. Under almost any conditions tested the Tm values are higher than those for rRNA from liver. rRNA from hepatomas differ from rRNA of normal liver in T m depending upon solvent conditions. Within pH 5-7 the T m values drop with decreasing [H ⊕ ], whereas at p H 8 they raise again in contrast to the behaviour of rRNA from liver. The dependence of the T m values on the ion strength is more pronounced for hepatoma rRNA. The differences in T m of rRNA from hepatomas and liver (ΔT m ) follow a direct linear dependence on log μ in presence of Na ⊕ . On the other hand, ΔT m increases in presence of Li® with decreasing ion strength. The direct relation between the ion radius of bivalent cations and T m values is less pronounced in the case of hepatoma rRNA compared with rRNA from liver.

The AA. using a fluorescence microscopical method demonstrated the presence of 5-HT in the myenteric plexus of the guinea-pig.

Es wird über Untersuchungen an einem permanenten Zellstamm (Mäusefibroblasten, L-strain, Earle) in der Gewebekultur berichtet, die sich mit der Lipidspeicherung dieser Zellen in Abhängigkeit von der Serumkonzentration befassen. Die Untersuchungen wurden morphologisch im Phasenkontrastmikroskop, histochemisch mittels der Sudanschwarz-B-Färbung sowie quantitativ vorgenommen. Bei steigender Serumzugabe zeigt sich eine zunehmende Lipideinlagerung, die als Speicherungsprozeß gedeutet wird. Eine gewisse Absättigung der Lipidaufnahme scheint mit 20-proz. Serumzusatz erreicht zu sein, da sich darüber hinaus keine Zunahme mehr beobachten ließ. Bei hohem Serumzusatz (ca. 40%) zum Nährmedium kommt es zu einer relativ verringerten Aufnahme von Phospholipiden bei Zunahme der Neutralfette.

Proteus mirabilis and its penicillin-induced L-Phase variants contain alanine racemase. The enzyme occurs in both the stable mucopolymer-free L-Phase and in the unstable mucopolymercontaining L-Phase of Proteus mirabilis. ᴅ-Alanine is found in appreciable amounts only in the mucopolymer-containing L-Phase. The inhibition of the alanine racemase by ᴅ-cycloserin results in growth inhibition in the mucopolymer-containing L-Phase only, whereas the growth of a stable mucopolymer-free L-Phase is unaffected. It thus appears that alanine racemase is not lost during the penicillin-induced transition of the bacterial form of Proteus mirabilis to the L-Phase, although the enzyme has no further function in the mucopolymer-free L-Phase. Two tested strains of Mycoplasma sp. showed neither alanine racemase activity nor did they contain ᴅ-alanine. It is suggested that the occurence of the enzyme may serve as a criterion in establishing the nature of a given organism as L-Phase variant of a bacterium or as a Mycoplasma strain.

It has been shown in a number of papers that the young gametophytes of ferns, e. g. Dryopteris filix-mas, will grow differently under red and under blue light. In red light these sporelings grow as filaments whereas under blue light they form two-dimensional normal prothallia. - The development of the sporelings can be inhibited by the application of methyl-tryptophane. The process of cell division is blocked by this treatment. The blue grown sporelings are much more sensitive than the red grown one. Under the influence of the antimetabolite methyl-tryptophane the nuclei will swell in both types of sporelings to about the same extent. The application of tryptophane reverses the effects of the antimetabolite on nuclear swelling, cell division and development in general. In the case of the blue grown sporelings much higher concentrations of tryptophane were needed to reverse the inhibition mediated by methyl-tryptophane. It is assumed that the application of methyl-tryptophane leads to a disintegration of protein and cell metabolism. The transport of substances from the nucleus to the cytoplasm is blocked under these conditions. The result is an accumulation of material in the nucleus which leads to swelling and finally to an inactivation of the nucleus as far as cell division and cell differentiation are concerned. The application of tryptophane gradually leads to a reconstitution of the normal cell metabolism. The swelling of the nucleus is reversed. Apparently the flow of material from the nucleus to the cytoplasm is taken up again which results in normal cell differentiation and mitotic activity.

Leaves, which had been killed in liquid air, were freeze dried and then fractionated by a nonaqueous method. Two fractions were obtained, one consisting of chloroplasts and the other of cytoplasm, vacuolar constituents, cell walls and residual chloroplasts. Calculation of the intracellular distribution of ascorbic acid based on the analysis of the two fractions revealed that 40 to 50% of the total ascorbic acid content of the cells is located within the chloroplasts. Since chloroplasts occupy less than 10% of the total volume of the cells, this high figure is direct evidence of an unequal distribution of ascorbic acid within the leaf cell.

By means of a new plating technique, single isolated cells from tissue cultures of Vitis vinifera could be grown with a plating efficiency between 60 and 70 percent. Division of these cells occurred only in the presence of living tissue fragments and cell groups. It is shown quantitatively that the rate as well as the time of division of these cells is determined by the weight of the inoculum. Some aspects of these findings and additional observations are discussed.