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PubMed1999

Prolonged negative selection of Drosophila melanogaster for a character of adaptive significance disturbs stress reactivity.

The metabolism of juvenile hormone by JH-esterase and JH-epoxide hydrolase, and octopamine by tyrosine decarboxylase were studied under normal and stress conditions in flies of two related lines of D. melanogaster. One was selected for high (HA line) and another for low (LA line) male sexual activity for more than 700 generations. It was demonstrated that prolonged selection for low male sexual activity results in considerable changes in both systems. Tyrosine decarboxylase activity in males and females of the LA line was sharply reduced as compared with those of the HA and control Canton-S lines; JH-esterase and JH-epoxide hydrolase activities were decreased in females, and not in males, of the LA line. It was demonstrated that the response of both metabolic systems to heat stress is impaired in individuals of the LA line: the system of juvenile hormone metabolism does not respond to stress, and that of octopamine metabolism is decelerated. The role of juvenile hormone metabolism in male reproductive function is discussed.

Adaptation, Biological↗
PubMed1994

Isolation and identification by gas chromatographic mass spectrometry of the carbonyl-active site of pig kidney diamine oxidase.

An adduct with phenylhydrazine was formed with the purified pig kidney diamine oxidase and in parallel with the l-tyrosine decarboxylase from Streptococcus faecalis. The labeled enzymes were hydrolyzed by chemical hydrolysis and the adducts released by hydrolysis were isolated and identified first in HPLC and successively in GC-MS. Both enzymes gave the same adduct which was identified as the phenylhydrazone of pyridoxal. The isolated adduct had the same retention time as the phenylhydrazone of pyridoxal in HPLC and in gas chromatography and showed the same molecular weight in mass spectrometry when chemical ionization was used and the same fragmentation in mass spectrometry when electronic impact was used. The reported results show that pig kidney diamine oxidase contains pyridoxal in the form of covalently linked pyridoxal phosphate which can be released from the enzyme only by chemical hydrolysis. Pig kidney diamine oxidase is therefore a pyridoxal enzyme such as l-tyrosine decarboxylase as hypothesized in the past but never clearly demonstrated.

Amine Oxidase (Copper-Containing)↗
PubMed1986

Inhibition of aromatic L-amino acid decarboxylase and tyrosine aminotransferase by the monoamine oxidase inhibitor phenelzine.

The concentration of p-tyramine in the rat striatum was increased significantly by intraperitoneal injection of phenelzine (5 or 100 mg/kg). Unlike other monoamine oxidase (MAO) inhibitors, phenelzine had no effect on p-tyramine levels in the first 1-2 h following injection. The high dose of phenelzine increased the p-tyramine levels much more than the low dose. In addition, the high dose of phenelzine increased striatal p-tyrosine levels significantly 12 h after injection. Further studies showed that phenelzine inhibited the tyrosine aminotransferase activity of rat liver homogenates; the IC50 was 50 microM. Phenelzine also inhibited the aromatic L-amino acid decarboxylase activity of rat brain homogenate with an IC50 of 25 microM. Following intraperitoneal injection of 100 mg/kg phenelzine, the initial concentration of phenelzine in the striatum appears to be high enough to inhibit aromatic L-amino acid decarboxylase. It is suggested that the multiple enzyme inhibition caused by administration of high doses of phenelzine accounts for its unusual effects on striatal p-tyramine levels compared with other MAO inhibitors, i.e., its initial lack of effect on p-tyramine levels followed later by very large increases in p-tyramine levels.

Animals↗
PubMed1989

Effect of vitamin B-6 nutrition on the levels of dopamine, dopamine metabolites, dopa decarboxylase activity, tyrosine, and GABA in the developing rat corpus striatum.

Evidence presented in this manuscript indicates that prenatal and postnatal vitamin B-6 undernutrition produces the loss of dopamine (DA) in the corpus striatum of the developing rat brain. The concentration of striatal DA in rats fed vitamin B-6 inadequate diets was significantly lower than rats fed optimal diets at 28 and 56 days of age. The differences in striatal DA concentrations among vitamin B-6 dietary groups was more evident with age. Measurements of the major metabolites of DA, homovanillic acid (HVA), and 3,4-dihydroxyphenylacetic acid (DOPAC) in rat corpus striatum showed a significant decrease in HVA level in B-6 restricted rats compared to B-6 sufficient groups. Striatal DOPAC levels were not significantly different among any of the groups at any age. The activity of dopa decarboxylase holoenzyme was found to be significantly lower in the corpus striatum of rats fed suboptimal B-6 diets. Whether this finding has a significant effect on DA levels has yet to be determined since dopa decarboxylase is not the rate-limiting enzyme in the synthesis of DA. In an effort to determine the underlying mechanism for the loss of striatal DA, the concentration of its precursor tyrosine (TYR) was measured. Vitamin B-6 undernutrition had no significant effect on the levels of TYR in rat corpus striatum. The concentration of the inhibitory neurotransmitter GABA was also measured. The results indicate that as expected the levels of striatal GABA were significantly lower than controls at 14 and 28 days of age. On the other hand, striatal GABA levels in B-6 restricted rats did not differ from controls at 56 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1975

The antibody-enzyme analogy. Comparison of enzymes and antibodies specific for phosphopyridoxyltyrosine.

Reduced Schiff base compounds of pyridoxal-P and tyrosine, which were used to induce specific antibodies described in the preceding article (V. Raso and B. D. Stolar, Biochemistry, 1975), caused active site-directed inhibition of tyrosine transaminase and tyrosine decarboxylase. The antibodies, studied as analogs of enzymes, were able to bind an unsaturated Schiff base catalytic intermediate, as shown by equilibrium dialysis and absorbance difference spectroscopy. Schiff base formation can proceed while the pyridoxal-P and tyrosine are within the antibody combining site, but the rate of this bimolecular condensation within the sites was not greater than the rate in free solution. Antibody did effect a small rate enhancement for the pyridoxal-P-catalyzed transamination of L-tyrosine. These results are discussed in light of current ideas in the mechanisms of enzyme catalysis.

Animals↗
PubMed2001

Effect of the interaction between a low tyramine-producing Lactobacillus and proteolytic staphylococci on biogenic amine production during ripening and storage of dry sausages.

The interaction between tyrosine-decarboxylase and proteolytic activities of a Lactobacillus curvatus and Staphylococcus xylosus, respectively, on biogenic amine production during the ripening and the storage of dry fermented sausages was investigated. Water content, pH, proteolysis parameters, microbial counts, and biogenic amine contents were monitored in spontaneously and starter fermented sausages. The use of proteolytic staphylococci as starter resulted in a higher content of non-protein nitrogen and total free amino acids. Tyramine was the main amine produced in all batches. However, tyrosine-decarboxylase activity of the L. curvatus starter strain was weak and yielded lower amounts of tyramine than those produced by the wild mioroflora in the control batch. Association between tyramine production and proteolysis could only be established in a defectively dried batch. Putrescine and cadaverine accumulation was efficiently reduced in the starter-mediated fermentation, in agreement with the lower development of enterobacteria. Phenylethylamine and tryptamine were only detected in the spontaneously fermented sausages, while histamine, spermine and spermidine did not vary during the ripening. Biogenic amine levels and related parameters showed significant changes during the storage of dry sausages depending on the temperature and the batch. As a general rule, changes in the pH, proteolysis, microbial counts, and biogenic amine contents were stronger at 19 degrees C than at 4 degrees C. The results suggest that refrigeration would be advisable for preventing further accumulation of biogenic amines during the storage of dry fermented sausages.

Biogenic Amines↗
PubMed2000

Humoral immunity against glutamic acid decarboxylase and tyrosine phosphatase IA-2 in Lambert-Eaton myasthenic syndrome.

Some beta-cell-specific autoantigens also are present in the central nervous system. Furthermore, stiff man syndrome, an autoimmune neurological disease, is frequently associated with diabetes and shares with this one an anti-GAD and IA-2 humoral immunoreactivity. We wondered whether these autoantibodies could be found in other neurological diseases with a present or supposed autoimmune origin. So, anti-GAD65 (GAD65A) and anti-IA-2 (IA-2A) autoantibodies were assayed in various neurological diseases. There was a higher prevalence of such antibodies in Lambert-Eaton myasthenic syndrome (LEMS) (GAD65A, 35%; IA-2A, 21%; double positivity, 18%) compared to amyotrophic lateral sclerosis (18%, 12%, and 12%, respectively) and multiple sclerosis (10%, 3%, and 3%, respectively). In LEMS, the humoral reaction was more frequent and/or appeared earlier in the paraneoplastic forms. The detection of such autoantibodies in patients with small-cell lung carcinoma (SCLC) without LEMS suggests that these autoantigens, GAD65 and IA-2, could be produced by SCLC tissue.

Adolescent↗
PubMed2005

Expression of human dopamine receptor in potato (Solanum tuberosum) results in altered tuber carbon metabolism.

BACKGROUND: Even though the catecholamines (dopamine, norepinephrine and epinephrine) have been detected in plants their role is poorly documented. Correlations between norepinephrine, soluble sugars and starch concentration have been recently reported for potato plants over-expressing tyrosine decarboxylase, the enzyme mediating the first step of catecholamine synthesis. More recently norepinephrine level was shown to significantly increase after osmotic stress, abscisic acid treatment and wounding. Therefore, it is possible that catecholamines might play a role in plant stress responses by modulating primary carbon metabolism, possibly by a mechanism similar to that in animal cells. Since to date no catecholamine receptor has been identified in plants we transformed potato plants with a cDNA encoding human dopamine receptor (HD1). RESULTS: Tuber analysis of transgenic plants revealed changes in the activities of key enzymes mediating sucrose to starch conversion (ADP-glucose phosphorylase and sucrose synthase) and sucrose synthesis (sucrose phosphate synthase) leading to altered content of both soluble sugars and starch. Surprisingly the catecholamine level measured in transgenic plants was significantly increased; the reason for this is as yet unknown. However the presence of the receptor affected a broader range of enzyme activities than those affected by the massive accumulation of norepinephrine reported for plants over-expressing tyrosine decarboxylase. Therefore, it is suggested that the presence of the exogenous receptor activates catecholamine cAMP signalling in plants. CONCLUSIONS: Our data support the possible involvement of catecholamines in regulating plant carbon metabolism via cAMP signalling pathway.

Carbohydrate Metabolism↗
PubMed1991

Enzymatic fluorometric assay for plasma pyridoxal 5'-phosphate.

An enzymatic fluorometric assay to quantitate plasma pyridoxal 5'-phosphate (PLP) is described. PLP is preincubated for 30 min with purified tyrosine decarboxylase apoenzyme (TDA) in acetate buffer and is then incubated with L-tyrosine for 60 min. The decarboxylated metabolite, tyramine, is extracted into ethyl acetate, air dried, dissolved in borate buffer and reacted with fluorescamine to form a fluorophor (395/475 nm). Recovery of exogenous PLP was 83%. After log-normal transformation of 129 plasma PLP levels obtained from 3 groups of subjects (in-patients, out-patients, staff), a normal distribution curve was obtained yielding a mean of 83 nmol/L. With 95% confidence level, the reference limits were 32-170 nmol/L. There were no age or sex differences in mean plasma PLP levels between any of the 3 groups of subjects studied.

Adolescent↗
PubMed2000

Plant aromatic L-amino acid decarboxylases: evolution, biochemistry, regulation, and metabolic engineering applications.

A comprehensive survey of the extensive literature relevant to the evolution, physiology, biochemistry, regulation, and genetic engineering applications of plant aromatic L-amino acid decarboxylases (AADCs) is presented. AADCs catalyze the pyridoxal-5'-phosphate (PLP)-dependent decarboxylation of select aromatic L-amino acids in plants, mammals, and insects. Two plant AADCs, L-tryptophan decarboxylase (TDC) and L-tyrosine decarboxylase (TYDC), have attracted considerable attention because of their role in the biosynthesis of pharmaceutically important monoterpenoid indole alkaloids and benzylisoquinoline alkaloids, respectively. Although plant and animal AADCs share extensive amino acid homology, the enzymes display striking differences in their substrate specificities. AADCs from mammals and insects accept a broad range of aromatic L-amino acids, whereas TDC and TYDC from plants exhibit exclusive substrate specificity for L-amino acids with either indole or phenol side chains, but not both. Recent biochemical and kinetic studies on animal AADCs support basic features of the classic AADC reaction mechanism. The catalytic mechanism involves the formation of a Schiff base between PLP and an invariable lysine residue, followed by a transaldimination reaction with an aromatic L-amino acid substrate. Both TDC and TYDC are primarily regulated at the transcriptional level by developmental and environmental factors. However, the putative post-translational regulation of TDC via the ubiquitin pathway, by an ATP-dependent proteolytic process, has also been suggested. Isolated TDC and TYDC genes have been used to genetically alter the regulation of secondary metabolic pathways derived from aromatic amino acids in several plant species. The metabolic modifications include increased serotonin levels, reduced indole glucosinolate levels, redirected shikimate metabolism, increased indole alkaloid levels, and increased cell wall-bound tyramine levels.

Amino Acid Sequence↗
PubMed1990

Modulation of lymphocyte proliferation by enzymes that degrade amino acids.

In a previous study we demonstrated thirteen amino acids to be essential and two to be partially essential for lymphocyte proliferation. Arginine is one of the essential amino acids, and the highly purified arginase strongly inhibited lymphocyte proliferation. The modulation of lymphocyte growth by various amino acid-degrading enzymes was studied. Peripheral lymphocytes were cultured in RPMI 1640 with or without amino acid-degrading enzyme for 72 h. A total of 17 commercial L-amino acid-degrading enzymes were studied. At 10 micrograms/ml, both lysine decarboxylase and asparaginase completely inhibited lymphocyte proliferation, arginase resulted in 78% inhibition and tyrosinase 57% inhibition. Other enzymes inhibited less than 20% lymphocyte proliferation; they included alanine dehydrogenase, arginine decarboxylase, aspartase, glutamic decarboxylase, glutamic dehydrogenase, glutaminase, histidase, histidine decarboxylase, leucine dehydrogenase, phenylalanine decarboxylase, phenylalanine hydroxylase, tryptophanase, and tyrosine decarboxylase. All four enzymes that strongly inhibited lymphocyte proliferation degraded amino acids that are essential for lymphocyte growth.

Arginase↗
PubMed2000

Isolation, properties and behaviour of tyramine-producing lactic acid bacteria from wine.

Wines containing high levels of biogenic amines were investigated for the presence of tyramine-producing strains. Two different Lactobacillus brevis (IOEB 9809 and IOEB 9901) able to produce the amine were isolated. None of the isolated strains identified as Oenococcus oeni formed tyramine. In addition, other Lact. brevis and Lact. hilgardii strains from our collection (IOEB) and the American Type Culture Collection (ATCC) were strong tyramine producers. Lactobacillus brevis IOEB 9809 and Lact. hilgardii IOEB 9649 were found to produce tyramine and phenylethylamine simultaneously. The conditions that can influence tyramine formation in wine were evaluated for three strains of Lact. brevis (IOEB 9809 and IOEB 9901) and Lact. hilgardii (IOEB 9649). Tyrosine was the major factor affecting tyramine formation and was enhanced by the presence of sugars, mainly glucose. Tyrosine decarboxylase (TDC) activity greatly depended on the presence of the precursor, which suggested that tyrosine induced the TDC system. These results indicate that Lactobacillus could be the lactic acid bacteria responsible for tyramine production in wine.

Lactobacillus↗
PubMed1977

Biochemical differentiation of aggregating cell cultures of different fetal rat brain regions.

Rotation-mediated aggregating cell cultures of mechanically dissociated fetal rat brains divided into three (telencephalon, mesencephalon-diencephalon and rhombencephalon), or two (telencephalon and mesencephalon-diencephalon plus rhombencephalon) parts were examined for their biochemical differentiation by measuring the specific activities of choline acetyltransferase, acetylcholinesterase, glutamic acid decarboxylase, tyrosine 3-monooxygenase, aromatic L-amino acid decarboxylase, catechol methyltransferase and monoamine oxidase. The results showed that such parts yielded cultures that were relatively enriched for acetylcholine-synthesizing (telencephalon) or catecholamine-synthesizing (mesencephalon-diencephalon and mesencephalon-diencephalon plus rhombencephalon) enzymes. For cultures which were derived from two brain divisions, the sum of the total activity for each enzyme in the parts after 30 days equalled that in whole brain cultures derived from the same group of embryos, suggesting that development of these enzymes was unaffected by division of the brain in two. In experiments to determine the effects of culture conditions on this development, chronic administration of certain drugs was found to selectively influence the specific activity of certain neurotransmitter metabolizing enzymes. Thus, in cultures of whole brain, ascorbic acid (0.2 mM) decreased tyrosine 3-monooxygenase and aromatic L-amino acid decarboxylase while other enzymes were slightly increased; and in cultures of telencephalon and mesencephalon-diencephalon plus rhombencephalon, N6, O2'-dibutyryladenosine 3',5'-cyclic phosphate (0.2 mM) decreased the specific activities of choline acetyltransferase acetylcholinesterase, glutamic acid decarboxylase and monoamine oxidase. These results demonstrate the feasibility of growing these cultures for pharmacological studies in developmental neurobiology.

Acetylcholinesterase↗