Reactions of phosphonate analogs of pyridoxal phosphate with apo-aspartate aminotransferase

We have investigated reactions of the 5-phosphonoethyl and 5-phosphonoethenyl analogs of pyridoxal 5'-phosphate in the coenzyme site of cytosolic aspartate aminotransferase. Acid dissociation constants and equilibrium constants for hydration and for tautomerization have been evaluated for these compounds. In confirmation of previous results, both compounds are partially active. They bind to apoenzyme well and undergo conversion in the presence of glutamate to amine forms which show induced circular dichroism comparable to that of native enzyme. A normal "external" Schiff base is evidently formed with 2-methylaspartate, but the amounts of quinonoid intermediate formed with erythro-3-hydroxyaspartate are less than those formed with pyridoxal phosphate. The pKa of the imine group of the enzyme reconstituted with the phosphonoethyl analog is more than two units lower than that in the native enzyme. Binding of the dicarboxylates glutarate, 2-oxoglutarate, and succinate shifts the pKa upward. The absorption spectra of the resulting complexes indicate the existence of at least three low pH species. A shift of 2.3 to 2.9 ppm to a lower frequency was observed for the 31P NMR signal upon binding of these dicarboxylates or of 2-methylaspartate. Enzyme containing the analogs crystallizes. Polarized absorption spectra suggest that the coenzyme has an orientation similar to that of pyridoxal phosphate in the native enzyme.

Clavulanate inactivation of Staphylococcus aureus beta-lactamase

The interaction of clavulanic acid with beta-lactamase from Staphylococcus aureus was investigated, particularly with a view to determining whether conformational effects are involved. The inactivation at neutral pH is essentially stoichiometric, leading to an inactive species with an enamine chromophore. Two forms of the enamine were observed, the first-formed having a positive ellipticity with a maximum near 290 nm. This species slowly converted into the stable form of the inactivated enzyme that had a negative ellipticity with a minimum at 275 nm. This change in sign of the ellipticity of the enamine is consistent with the previously proposed cis-trans isomerization of the enamine [Cartwright & Coulson (1979) Nature (London) 278, 360-361). Both the far-u.v.c.d. and the intrinsic viscosity of the inactivated enzyme indicated that negligible change in conformation of the enzyme accompanied inactivation. The rates of inactivation and enamine formation were compared at low temperatures, where the initial rates were slow enough to be monitored. The rate of loss of 95% of the catalytic activity was almost 100-fold faster than the rate of formation of the first-formed enamine species. The remaining 5% activity was lost with a rate comparable with that for formation of the initial enamine. The simplest explanation of these results is that a relatively stable acyl-enzyme intermediate builds up initially and more slowly partitions between turnover (hydrolysis) and enamine formation. The initially formed enamine is in the cis conformation but slowly isomerizes to the more stable trans form.

[In vitro and in vivo production of amines by a Lactobacillus strain isolated from a cock crop]

The chicken digestive tract is mainly colonized by bacteria belonging to the Lactobacillus genus. One of these strains (LEM-207) isolated from the crop of a cock and closely resembling L. acidophilus, was able to develop on a carbohydrate-free medium. Production of carbon dioxide and synthesis of tyramine, putrescine and cadaverine were observed in the cultures. Once implanted in the crops of germ-free chickens, strain LEM-207 led to the formation of amines. In germ-free (axenic) animals, only endogenous tyramine was detected, whereas in monoassociated chickens, we found a production of tyramine, cadaverine and putrescine. The concentrations of cadaverine and putrescine decreased with increasing acidification of the contents, whereas the level of tyramine increased (7-fold higher level than in germ-free chicken). Amine production was not detected in the caeca. The toxicological aspects of tyramine production in terms of the animal are discussed.

Role of calmodulin in neurotransmitter synthesis

Tyrosine 3-monooxygenase (EC 1.14.16.2) and tryptophan 5-monooxygenase (EC 1.14.16.4) are generally believed to be the rate-limiting enzymes in the biosynthesis of the neurotransmitters, catecholamines and serotonin, respectively, and therefore the regulation of their activities is of particular importance. At least three calmodulin-dependent protein kinases differed in their molecular weights and substrate specificities, designated I, II, and III in the order of decreasing molecular weight, in rat brain cytosol. Among them, calmodulin-dependent protein kinase II with a molecular weight of about 540,000 appeared to occur only in the nervous tissues. Kinase II was found, on the one hand, to phosphorylate tyrosine 3-monooxygenase and tryptophan 5-monooxygenase, leading to the activation of these monooxygenases in the presence of activator protein and, on the other hand, to phosphorylate tubulin and microtubule-associated protein 2, which results in disassembly of the microtubules that had been assembled. These results suggest the possibility that both the secretion and biosynthesis of monoamine neurotransmitters stimulated by Ca2+ influx in the nervous system may be regulated by calmodulin-dependent protein kinase II via the phosphorylation of microtubule proteins and the phosphorylation of the monooxygenases that are the rate-limiting enzymes in the biosynthesis of the neurotransmitters.

Frequency-pulsed electron capture gas-liquid chromatographic analysis of metabolites produced by Clostridium difficile in broth enriched with amino acids

Clostridium difficile strain CDC A-567 was cultured in Trypticase (BBL Microbiology Systems)-yeast-salt broth supplemented with 0.2% L-leucine, L-norleucine, L-isoleucine, L-tyrosine, or L-tryptophan. Four extractions were done on the spent medium, three at pH 2 and one at pH 10, using CHCL3 or ether. Derivatizations were done with trichloroethanol, heptafluorobutyric anhydride, and heptafluorobutyric anhydride-ethanol. All samples were analyzed with frequency-pulsed electron capture gas-liquid chromatography. A dedicated computer was used to assist in data analysis. C. difficile produced both short-chain and aromatic acids in Trypticase-yeast-salt broth; hydroxy acids were also detected. p-Cresol, indoleacetic acid, 4-methylthio-2-hydroxybutyric acid, and some unidentified alcohols were observed. The basic chloroform extraction contained cadaverine and putrescine. Leucine, norleucine, and isoleucine influenced the production of C5 and C6 acids and alcohols. L-Tyrosine underwent successive degradation to produce p-cresol and aromatic acids as final products. Tryptophan increased the production of indoleacetic, indolepropionic, and indolebutyric acids. Isocaproic acid was produced in relatively high concentrations regardless of medium substitution. The consistent production of iC6 under various substrate conditions indicates that the production of this compound might be consistent enough in vitro to form the basis of a rapid test for detection of C. difficile in stool specimens by frequency-pulsed electron capture gas-liquid chromatography.

Biosynthesis of some urinary trace amines in the rat and the human

The biosynthesis and urinary excretion of the trace amines PE, mTA, pTA and TRYP have been investigated after systemic injection in the rat and ingestion in the human. In the rat the likely precursors phe, tyr, DOPA and PE, radioactively labelled, were injected in tracer and supplemented doses. pTA was shown to be formed from PE and ptyr and in tiny amounts from phe and DOPA. mTA was formed from PE, phe and DOPA. PE was found after phe and PE injections. In the human, after ingestion of the deuterated precursors phe, ptyr, PE and try, only deuterated PE and mTA were located after phe, deuterated pTA after ptyr, deuterated PE after PE and deuterated TRYP after try. These results suggest that in the periphery pTA may be formed by p-hydroxylation of PE as well as by decarboxylation of ptyr while PE and TRYP are formed by decarboxylation of their parent amino acids phe and try respectively. PE is also a possible source of mTA but in this case hydroxylation and decarboxylation of phe and dehydroxylation and decarboxylation (or vice versa) of DOPA are also important.

Biogenic monoamines in developing taste buds of mouse circumvallate papillae

After administration of monoamine precursors, developing taste buds of newborn and young mice were observed by means of electron microscopy and fluorescence histochemistry. Gustatory (type III) cells occurred in the primitive taste buds during stage 1 (0-1 day after birth). These cells had an immature type of afferent synaptic contacts with nerve terminals; however, no specific fluorescence was found in the taste buds after administration of 5-HTP or L-DOPA. During stage 2 (2-7 days), mature types of afferent synapses, taste pores, type I cells and type II cells appeared in the taste buds, and fluorescent cells also appeared following treatment of 5-HTP or L-DOPA. During stage 3 (14-21 days), the gustatory cells underwent ultrastructural changes following injection of 5-HTP; i.e. small dense-cored vesicles (30-60 nm) appeared scattered throughout the cytoplasm and were found to intermingle with small clear vesicles accumulated at the presynaptic membranes of afferent synapses, and the electron densities of large dense-cored vesicles (80-100 nm) were elevated as compared with those of untreated mice. Consequently the ability of gustatory cells to take up amine-precursors started simultaneously with the formation of taste pores and mature afferent synapses between the gustatory cells and the sensory nerves.

The ability of amine production by argyrophil cell adenocarcinoma of the endometrium

The ability of amine production of argyrophil cell adenocarcinoma of the endometrium was studied by wet-histofluorescence method. The intense green and yellow fluorescence was detected for the first time in the cytoplasm of a few tumor cells by injecting amine precursor (L-Dopa) 3mg intraperitoneally to nude mice, who were transplanted serially with argyrophil cell adenocarcinoma of the endometrium. Similar fluorescence was also located in a few epithelial cells of the small intestine prepared from the same nude mice. These findings strongly suggested that these fluorescent products were amines. In order to specify the sorts of amines, the microspectrophotometric analyses are now in progress.

Differentiation of Peptococcus and Peptostreptococcus by gas-liquid chromatography of cellular fatty acids and metabolic products

Gas-liquid chromatographic (GLC) profiles of cellular fatty acids and metabolic products were useful in identifying strains of Peptococcus saccharolyticus, Peptococcus asaccharolyticus, Peptostreptococcus anaerobius, Peptostreptococcus micros, and Streptococcus intermedius. The GLC results supported the recent taxonomic decision to transfer aerotolerant Peptostreptococcus species to the genus Streptococcus. Because inconsistencies in the results prevented our differentiating Peptococcus prevotii. Peptococcus magnus, and Peptococcus variabilis by GLC, additional strains will have to been examined. These GLC techniques are amenable to routine use; however, for interlaboratory results to be meaningful, the classification and nomenclature of the anaerobic gram-positive cocci should be standardized.

Identification of Neisseria by electron capture gas-liquid chromatography of metabolites in a chemically defined growth medium

A dual-purpose study was carried out in an attempt to develop a rapid, sensitive method to identify Neisseria species by gas chromatography and to learn more about the metabolism of these organisms. Sixty-nine isolates of Neisseria were grown in a chemically defined fluid medium; the spent medium was extracted sequentially at pH 2 with diethyl ether and at pH 10 with chloroform. The pH 10 extracts were derivatized with heptafluorobutyric anhydride and analyzed by electron capture gas-liquid chromatography. The resulting spent culture medium electron capture gas-liquid chromatography profiles showed several qualitative and significant quantitative differences among the Neisseria species potentially useful in separating and identifying these organisms. Putrescine and cadaverine which were present in the spent culture medium of some Neisseria, including N. gonorrhoeae, were tentatively identified. Substituting carbohydrates for the chemically defined medium containing glucose in the base medium produced altered profiles with increased quantitative and qualitative differences.

4-Nitrobenzoic acid reductase of Ascaris lumbricoides var suum. Substrate specificity and reaction products

1. The substrate specificity of nitro-reductase from Ascaris lumbricoides varsum was determined. This enzyme reduced nitrobenzene, 4-nitrohippuric acid and the isomers of nitrophenol, nitroanisole, nitrobenzoic acid, nitrobenzaldehyde and nitrobenzyl alcohol. The same enzyme preparation reduced azobenzene, 4-dimethylaminoazobenzene and 1,2-dimethyl-4-(4-carboxyphenylazo)-5-hydroxybenzene. Nitrobenzaldehyde isomers were not reduced to the alcohols. 2. The products of nitro- and azo-reduction were the corresponding amines, no hydroxylamino or hydrazo compounds were detected. 3. The pH optima and cofactor requirements were the same for both azo- and nitro-reduction and neither reaction was inhibited by oxygen. 4. Ammonium sulphate fractionation failed to separate azo- and nitro-reductase activities. The molecular weight of both azo- and nitro-reductase was about 130 000.

Synthesis and chromatographic properties of cysthationamine. A substrate for diamineoidase

Details are reported for the preparation of the 2-aminoethyl, 3-aminopropyl sulfide from 3-bromopropylamine and 2-mercaptoethylamine. For this compound, the shorter name cystathionamine is proposed. The corresponding sulfoxide and sulfone have been also prepared. Some analytical data and chromatographic properties are reported. Preliminary results show that cystathionamine is a good substrate for the pig kidney diamineoxidase.

Biosynthesis of p-aminophenylalanine: part of a general scheme for the biosynthesis of chorisimic acid derivatives

p-Aminophenylalanine is biosynthesized in Vigna vexillata (L.) A. Rich. from shikimic acid through a pathway different from that giving phenylalanine and tyrosine. Experiments with 1,6-14C-labelled shikimic acid demonstrate that the C3-side chain in p-aminophenylalanine is attached to the original C-1 in shikimic acid. The biosynthesis of p-aminophenylalanine in Vigna vexillata probably follows the same pathway as the biosynthesis of this amino acid in Streptomyces species where it is known to be an intermediate in the biosynthesis of chloramphenicol. It is proposed that the biosynthesis takes place through chorismic acid, 4-amino-3-enolpyruvylcyclohexa-1,5-dienecarboxylic acid, 3-(4-amino-1-carboxycyclohexa-2,5-dienyl) pyruvic acid, and 4'-aminophenyl-yruvic acid. It is proposed that chorismic acid can gave rise to 4-amino-3-enolpyruvylcyclohexa-1,5-dienecarboxylic acid, 2-amino-3-enolpyruvylcyclohexa-4,6-dienecarboxylic acid, and isochorismic acid, and that these three compounds and chorismic acid itself by simple rearrangements and elimination reactions can give rise to most known chorismic acid derivatives, i. e.p-hydroxybenzoic acid, 3,4-dihydroxy-3,4-dihydrobenzoic acid, phenylalanine, tyrosine, p-aminobenzoic acid, p-aminophenylalanine, anthranilic acid, 2-amino-3-hydroxy-2,3-dihydrobenzoic acid, 3-(3-carobxyphenyl) alanine, 3-(3-carbocy-4-hydrocyphenyl) alanine, salicylic acid, and 2,3-dihydroxy2,3-dihydrobenzoic acid.

Central monaminergic neuronal effects on minimum alveolar concentrations (MAC) of halothane and cyclopropane in rats

The effect of interference with central catecholamine- or serotonin-containing neurons on the response of rats to inhalation anesthetics were explored. Interference with catecholaminergic function by inhibition of amine synthesis with alpha-methyltyrosine alone or combined with destruction of these neurons by 6-hydroxydopamine reduced brain concentrations of norepinephrine and dopamine without altering serotonin concentrations. These alterations decreased the minimum alveolar concentration (MAC) of halothane when tail-clamping was used as the test stimulus. Similar small reductions of halothane MAC were produced in rats given 5,6-dihydroxytryptamine and p-chlorophenylalanine, which decreased brain serotonin without altering noreopinephrine or doapamine concentrations. When catecholaminergic or serotoninergic neuronal function was similarly disrupted in rats later exposed to cyclopropane, no alternation in MAC was observed. It is suggested that disruption of central amine-containing neurons may lower the MAC's of depressant anesthetics only, and not excitatory anesthetics.

Regulation of chloramphenicol synthesis in Streptomyces sp. 3022a. Properties of arylamine synthetase, an enzyme involved in antibiotic biosynthesis

A new arylamine synthetase activity has been demonstrated in Streptomyces sp. 3022a when grown under chloramphenicol-producing conditions. The enzyme has several characteristics which distinguish it from anthranilate synthetase. It converts chorismic acid to an, as yet, unidentified aromatic amine easily separable from anthranilic and p-aminobenzoic acids. This arylamine synthetase was absent from strains of Streptomyces sp. 3022a, which were incapable of chloramphenicol production. The addition of chloramphenicol to growing cultures repressed arylamine synthetase but not anthranilate synthetase activity. The role of arylamine synthetase in the control and regulation of chloramphenicol biosynthesis is discussed.

Possible interaction of environmental and biological factors in the etiology of schizophrenia. Review and integration

Possible interactions of genetic and environmental factors in the etiology of schizophrenia are discussed.

Studies on the significance of genetic-constitutional and environmental factors in determining specificity of behavioural and biochemical responses to stressors in humans and experimental animals are reviewed.

Studies of stress in schizophrenia are also revieweed and their possible relationships discussed.

Hypotheses related to the interaction of environmental factors and genetic constitutional factors in the production of acute schizophrenic psychosis in genetically predisposed people are presented. Research studies supporting such hypotheses are reviewed and discussed.

It is proposed that environmental pressures, by inducing a physiological state of stress or other biochemical physiological alterations, may be etiologically related to the development of acute schizophrenic psychosis by:

• Producing chemical substances that act as inducers of enzymes, in particular transmefhylating enzymes and those involved in the production of proteins, which may be related to the etiology of schizophrenia;

• Activating autoimmune processes which may be related to the etiology of schizophrenia;

• Changing levels of brain amines;

•Altering the permeability of the blood-brain barrier.

Metabolic disposition of 2,4,6-trinitrotoluene

Three pseudomonas-like organisms have been shown to metabolically oxidize 2, 4, 6-trinitrotoluene (TNT). Capability for this oxidative dissimilation varied with each organism. Of the three, isolate "Y" was the most proficient, isolate "I" was less, and isolate "II" was the least. For accelerated TNT degradation, addition of glucose or a nitrogenous substance was essential. Complete dissimilation within 24 h by isolate "Y" cultures supplemented with 0.5% yeast extract is presumed since no TNT was detectable.

Metabolism of penicillins to penicilloic acids and 6-aminopenicillanic acid in man and its significance in assessing penicillin absorption

Penicillins can be metabolized to penicilloic acids in man, the extent being dependent on the penicillin structure. In the phenoxy penicillin series, phenoxymethyl penicillin was found to be particularly unstable, but the higher homologues were more stable. In the isoxazolyl series, oxacillin was unstable, and progressive insertion of halogen in the phenyl ring increased stability. Ampicillin and amoxycillin showed some instability, ampicillin possibly being the more stable. After intramuscular administration, carbenicillin was very stable in the body, ampicillin was fairly stable, and benzyl penicillin was unstable. It is important to take into account the penicilloic acid content of urine when estimating total absorption of a penicillin. Increased stability in the body as well as slower renal clearance can lead to high concentrations in the serum. Penicilloic acids seemed to be more slowly cleared from the body than penicillins. The liver is probably the site of inactivation.

Rapid methods for determining decarboxylase activity: ornithine and lysine decarboxylases

A rapid biochemical method for the determination of ornithine and lysine decarboxylase (EC 4.1.1.18) activity has been developed for use in the routine clinical laboratory. It is based on the detection of the amine end product produced in response to the single key amino acid added to a synthetic medium. A modified ninhydrin reagent is used to detect the amine after a chloroform extraction. This procedure can be used with a 1- to 4-hr incubation period (utilizing an initial concentrated inoculum) or with an overnight culture. Thus, measurements based on the alkalinization of the medium after a lengthy incubation period are avoided. Optimal parameters for enzyme activity are discussed.

Rapid methods for determining decarboxylase activity: arginine decarboxylase

A rapid biochemical method for the determination of arginine decarboxylase (EC 4.1.1.19) activity has been developed for use in the routine clinical microbiology laboratory and correlated with similar procedures for ornithine and lysine decarboxylase (EC 4.1.1.18) systems. It is based on the detection of agmatine, the amine end product formed during growth on a synthetic medium containing arginine as the key amino acid. A modified diacetyl reagent is used to detect this amine after a differential butanol extraction of the cultures. This procedure can be used to detect this amine after a 1- to 4-hr incubation period (with the use of an initial concentrated inoculum) or with an overnight culture. Thus, both an indirect measurement based on the alkalinization of the medium and a lengthy incubation period were avoided. Parameters for optimal enzyme activity and the pertinent enzyme systems involved in arginine and agmatine catabolism are discussed in detail.