Über Ester der Polygalakturonsäure

Summary Polygalacturonic acids (pectic acids) can easily be esterified by epoxides (ethylene oxide, 2,3-epoxy-1-propanol, epichlorhydrin, etc.) in the presence of water. Under favorable conditions the degradation of the macromolecules is negligible. Some properties of the glycol esters of polygalacturonic acid which are similar to those of the methyl esters of polygalacturonic acid (pectinic acids) are described. The glycol and glycerol esters, however, are not saponified by the enzyme pectase. These compounds react much more rapidly with formaldehyde than pectinic acid which does not possess primary hydroxyl groups.     

Synthetic simulation of nonribosomal peptide biosynthesis. A dual role of alkylthiol esters in peptide synthesis

Summary Coupling of peptide alkylthiol esters with amino acid derivatives in the presence of pivalic acid or 2-hydroxypyridine proceeds without racemization. A dual role of alkylthiol esters as protective and reactive functions in peptide synthesis was well proved.     

Interference with histamine and imidazole acetic acid metabolism by salicylates: a possible contribution to salicylate analgesic activity?

In man, rats and mice, the urinary excretion of the histamine and L-histidine metabolite, imidazole acetic acid, is increased and that of the conjugated metabolite, ribosylimidazole acetic acid, decreased by small doses of salicylates. In contrast to salicylates, other non-salicylate anti-inflammatory drugs, indomethacin, phenylbutazone, phenacetin and acetaminophen do not influence the excretion of the urinary metabolites of histamine and L-histidine. Since imidazole acetic acid is reported to have analgesic and narcotic activity, there is the inference that the analgesic properties of salicylate might be due in part to interference in imidazole acetic acid metabolism.     

Interference with histamine and imidazole acetic acid metabolism by salicylates: A possible contribution to salicylate analgesic activity?

Summary In man, rats and mice, the urinary excretion of the histamine andl-histidine metabolite, imidazole acetic acid, is increased and that of the conjugated metabolite, ribosylimidazole acetic acid, decreased by small doses of salicylates. In contrast to salicylates, other non-salicylate anti-inflammatory drugs, indomethacin, phenylbutazone, phenacetin and acetaminophen do not influence the excretion of the urinary metabolites of histamine andl-histidine. Since imidazole acetic acid is reported to have analgesic and narcotic activity, there is the inference that the analgesic properties of salicylate might be due in part to interference in imidazole acetic acid metabolism.     

Pentagastrine,histamine et acide ascorbique de la muqueuse gastrique chez le rat

Summary Pentagastrin and histamine, 2 potent gastric acid stimulants, lower ascorbic acid in the rat's gastric mucosa. They give the same result as nerve stimulation by desoxyglucose. Explanation of ascorbic acid function in gastric physiology needs further work.     

Labile protein-methyl ester: Comparison between chemically and enzymatically synthesized

Summary The rate of hydrolysis of protein-methyl ester, the enzymatic product of S-adenosylmethionine: proteincarboxyl methyltransferase (EC.2.1.1.24) acting on oxidized ribonuclease, was measured at pH 7.1 and 8.6 at 37°C. The half-life of the hydrolysis of the ester is 25 min at pH 7.1, and 4 min at 8.6. The rate of hydrolysis of the enzymatically formed esters at pH 7.0, in 0.1M phosphate buffer, was about 25 times faster than that of esters formed chemically by reaction with methanol in HCl. The lability of the enzymatically synthesized protein-methyl ester suggests that the esterification is specific to sites such that ionization of neighboring amino acid side chains enhances the rate of the hydrolysis.Acknowledgments. This work was supported by Research Grants AM 09603 from the National Institute of Arthritis and Metabolic Diseases, CA 10439 and CA 12226 from the National Cancer Institute, 1-P01-HD-05874 from the National Institute of Child Health and Human Development, National Institutes of Health, GM 20594-03 from National Institute of General Medical Sciences, USA.     

Reactions of cysteine, its derivatives, glutathione coenzyme A, and dihydrolipoic acid with isothiocyanates.

Isothiocyanates react with deprotonated SH groups of investigated compounds to give the esters of N-monosubstituted dithiocarbamic acid. In the presence of the SH and NH2 groups (Cys, GSH), isothiocyanates react primarily with the SH groups. The reactions are dependent on the pKa SH values.     

Die Beeinflussung der Fibrinogengerinnung durch Ribosenukleinsäure und adenosintriphosphorsaures Na (ATP)

Summary The coagulation of fibrinogen by thrombin is delayed by yeast nucleic acid and still more by adenosin-3-phosphoric acid. This action is due to a free phosphoric acid group and can be measured already in concentrations of 6 mg% yeast nucleic acid or of 2 mg% adenosin-3-phosphoric acid, whereas ATP only becomes effective in a concentration of 75 mg %.     

Über einige pharmakologische Untersuchungen synthetischer Alkoxy-tropinderivate

Summary Some pharmacological properties of new synthetic alkoxy-tropine derivatives are reported. The tertiary compounds were relatively potent local anaesthetics with a low anti-cholinergic action. Acetylcholine inhibition, as well as the spasmolytic activityin vivo of the benzilic acid esters were markedly increased by quaternisation while their toxicity decreased. 6-Methoxytropine benzilic acid ester brom-methylate was the most active compound of this series. A pronounced inhibitory activity on neurogenically induced intestinal constriction was found in low doses, whereas larger doses exerted a ganglionic blocking effect.     

Reactions of cysteine,its derivatives,glutathione, coenzyme A,and dihydrolipoic acid with isothiocyanates

Summary Isothiocyanates react with deprotonated SH groups of investigated compounds to give the esters of N-monosubstituted dithiocarbamic acid. In the presence of the SH and NH₂ groups (Cys, GSH), isothiocyanates react primarily with the SH groups. The reactions are dependent on the pK_aSH values.     

Modification of the action of pentagastrin on acid secretion by botulinum toxin.

I.v botulinum toxin after 60-90 min abolished the dose-response relationship between pentagastrin and gastric acid secretion in anesthetized rats and guinea-pigs. The toxin reduced but did not abolish the acid stimulatory effect of histamine. As expected, the acid response to vagal stimulation was abolished and that to methacholine in rats was unaltered by the toxin.     

Inhibition of molybdenum blue formation by ATP

Summary Molybdenum blue formation was not affected by the presence of ATP up to a concentration of 1.2 mM/l. At higher concentrations the color development was inhibited relative to ATP concentration, finally reaching complete inhibition. Auto-hydrolysis of ATP was found at a rate of 1.4%/h. An exact determination of inorganic phosphate in the presence of easily hydrolyzed phosphate esters requires the measurement of extinction at fixed time intervals and extrapolation back to time zero.Acknowledgment. This work was supported by a grant of the Deutsche Forschungsgemeinschaft.     

Propriétés antiacétylcholinestérasiques du diiodométhylate debis-(diméthylamino-3-phénoxy)-1-3 propane,de ses dérivés phénoliques et des esters carbamiques correspondants

Summary Thein vitro anti-acetylcholinesterase properties ofbis-(dimethylamino-3-phenoxy)-1-3 propane dimethiodide (2842 CT) of two phenolics derivatives (3443 CT and 3116 CT) and of the two corresponding carbamic esters (3152 CT et 3113 CT) have been compared using human red blood corpuscles as enzyme source; under specified conditions, the Cl-50 are respectively 8 × 10^–7 M for 2842 CT, 3.5 × 10^–9 for the two phenolic compounds, and 1.5 × 10^–9 for the carbamic esters. The potencies of these phenols are very close to those of the carbamates, being a bit higher or lower depending on the concentration of the inhibitor and on the time of the readingThe two phenolic compounds, like 2842 CT, react readily with the enzyme contrarily to the carbamic esters which combine slowly. On the other hand the inhibition by the phenolic derivatives is as stable against washing as that by the carbamates. The carbamates, but not the phenols, show the slow displacement phenomenon.Some of these characteristics are compatible with the hypothesis that carbamic compounds could act through liberated phenolic functions but others indicate that carbamic groups have a role of their own.     

Green tea epigallocatechin-3-gallate is an inhibitor of mammalian histidine decarboxylase

(–)-Epigallocatechin-3-gallate, an antiproliferative and antiangiogenic component of green tea, has been reported to inhibit dopa decarboxylase. In this report, we show that this compound also inhibits histidine decarboxylase, the enzymic activity responsible for histamine biosynthesis. This inhibition was proved by a double approach, activity measurements and UV-Vis spectra of enzyme-bound pyridoxal-5-phosphate. At 0.1mM (–)-epigallocatechin-3-gallate, histidine decarboxylase activity was inhibited by more than 60% and the typical spectrum of the internal aldimine form shifted to a stable major maximum at 345nm, suggesting that the compound causes a stable change in the structure of the holoenzyme. Since histamine release is one of the primary events in many inflammatory responses, a new potential application of (–)-epigallocatechin-3-gallate in prevention or treatment of inflammatory processes is suggested by these data.Received 8 April 2003; received after revision 20 May 2003; accepted 3 June 2003     

Novel substrates for the kinetic assay of esterases associated with insecticide resistance

Naphthalene thioesters were synthesized as substrates for a continuous, non- disruptive kinetic assay of general carboxylesterase activity. The continuous nature of the assay is based on the production of a soluble dianion chromophore from the reaction of naphthalene thio with 5,5-dithiobis (2-nitrobenzoic acid). Applications with 1- and 2-naphthalene thioacetates demonstrated their use in a fast accurate kinetic microassay of esterase activity, using porcine carboxylesterase as a model. These novel esters proved to be useful as substrates for the spectrophotometric assay of insecticide-resistance in two aphid species and may be applicable to other esterasebased diagnostic procedures.     

Chelate aus Diarylborinsäuren undβ-Ketosäureestern

Summary Diarylborinic acids form stable chelates with-keto acid esters. Borinic acids, when being synthetized, can be stabilized in compounds resulting from the combination with-keto acid esters. The chelates so formed are suitable—like the free borinic acids or their anhydrides—for further transformation. These chelates have several advantages in comparison with those formed with-amino ethanol.     

Female sex pheromone of the longhorn beetleMigdolus fryanus Westwood: N-(2′S)-methylbutanoyl 2-methylbutylamine

The first known long-range female-released sex pheromone for the family Cerambycidae is reported fromMigdolus fryanus, a sugarcane pest in South America. Although two female-specific compounds, namely, N-(2S)-methylbutanoyl 2-methylbutylamine and N-formyll-isoleucine methyl esters were identified, field tests with synthetic chemicals revealed that only the amide was active and that the amino acid derivative neither increased or decreased trap catches by the amide. This is the first identification of amide as a sex pheromone.     

Die oxydative Phosphorylierung isolierter Mitochondrien und ihre Abhängigkeit von strukturgebundenen Faktoren

Summary The ability of isolated mitochondria in coupling phosphorylation to oxidation depends on sufficient concentrations of intramitochondrially bound adenine nucleotides (especially ATP), compounds of oxidative metabolism (pyruvic and lactic acid) and iron ions. Continuous loss of these components by ageing causes at first a parallel lowering of phosphate uptake and does not affect respiration. Later on, a decrease of oxidative ability begins when the loss of intramitochondrial components reaches a limiting concentration, and now mitochondria show more and more swelling and structural damages.      

Histamine production in mixed culture between allograft donor and recipient lymphocytes]

An increased production of histamine has been demonstrated during mixed cultures between allograft donor and recipient lymphocytes. This phenomenon could result from the action of a non-dialysable factor released by recipient cells in the presence of donor cells. This factor is able to increase histamine production from normal spleen cells. Little or no increase in histamine production is found during primary and mixed lymphocyte cultures (without previous allograft).     

Untersuchungen an Ionenaustauschmodellen zum Verständnis der Physiologie biogener Amine. Austauschversuche an einem schwefelsäuregruppentragenden Harz zum Verständnis von sogenannten Histaminliberationsvorgängen

Summary Mixtures of histamine and other basic substances as hydrochlorides were added in equivalent amounts to an acid ion exchange system containing SO₄-groups in the H⁺-form (Dowex 50 W × 2). After completion of the equilibrium, the amounts of both the free histamine and the competing substance were determined by potentiometric titration.Values are presented for the relative amounts of each substance which are retained by the resin.The results obtained show that histamine and a given competing substance are selectively distributed on the resin. The method may be useful as a test for the possible histamine-liberating capacity of biologically important substances.