Showing papers on "Decarboxylation published in 1974"
279 citations
TL;DR: The two catalytic components of the E. coli acetyl-CoA carboxylase system are devoid of free or covalently bound biotin yet have the ability to carry out their respective model half-reactions utilizing free d-biotin derivatives in place of carboxy carrier protein.
200 citations
TL;DR: Pyrolysis of several structurally different amino acids in a column at 500 C showed differences in the mechanisms and final products, and alpha amino acids with alpha alkyl substituents appear to stabilize the developing negative charge formed by partial heterolytic cleavage of the alpha carbon - NH3 bond.
Abstract: Pyrolysis of several structurally different amino acids in a column at 500 C showed differences in the mechanisms and final products. The aliphatic protein amino acids decompose mainly by simple decarboxylation and condensation reactions, while the beta amino acids undergo deamination to unsaturated acids. Alpha amino acids with alpha alkyl substituents undergo an unusual intramolecular SN1 reaction with the formation of an intermediate alpha lactone which decomposes to yield a ketone. The alpha alkyl substituents appear to stabilize the developing negative charge formed by partial heterolytic cleavage of the alpha carbon - NH3 bond. The gamma and delta amino acids give 2-pyrrolidinone and 2-piperidone respectively, while the epsilon acids yield mixed products.
155 citations
TL;DR: Two new metabolites, 5-carboxymethyl-2-hydroxymuconic acid and 2-hydroxyhepta-2,4-diene-1,7-dioic acid, were isolated from reaction mixtures and a third, 4-Hydroxyphenylacetic acid, was shown to be cleaved by extracts to give pyruvate and succinic semialdehyde.
Abstract: A species of Acinetobacter and two strains of Pseudomonas putida when grown with 4-hydroxyphenylacetic acid gave cell extracts that converted 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid) into carbon dioxide, pyruvate, and succinate. The sequence of enzyme-catalyzed steps was as follows: ring-fission by a 2,3-dioxygenase, nicotinamide adenine dinucleotide-dependent dehydrogenation, decarboxylation, hydration, aldol fission, and oxidation of succinic semialdehyde. Two new metabolites, 5-carboxymethyl-2-hydroxymuconic acid and 2-hydroxyhepta-2,4-diene-1,7-dioic acid, were isolated from reaction mixtures and a third, 4-hydroxy-2-ketopimelic acid, was shown to be cleaved by extracts to give pyruvate and succinic semialdehyde. Enzymes of this metabolic pathway were present in Acinetobacter grown with 4-hydroxyphenylacetic acid but were effectively absent when 3-hydroxyphenylacetic acid or phenylacetic acid served as sources of carbon.
130 citations
TL;DR: The two catalytic components of the E. coli carboxylase system, although devoid of covalently bound biotin, catalyze model reactions with free d-biotin derivatives which account for their respective roles in Reactions 1 and 2 and show that each component possesses a specific binding site for the bicyclic ring of the prosthetic group.
104 citations
TL;DR: In this paper, it was shown that the addition of glutathione + gluthathione peroxidase greatly increases the formation of d -2-hydroxypalmitate from palmitate, with a concomitant decrease in CO 2.
89 citations
TL;DR: It appears that myeloperoxidase (MPO) can not only decarboxylate free and bound amino acids, yielding aldehydes, but also it can actively participate in oxidative peptide cleavage, which may play a critical role in the microbicidal action of the leukocyte.
Abstract: The antimicrobial activities of the myeloperoxidase-H2O2-halide system have received considerable attention recently. The precise mechanism by which this system exerts its lethal activity is presently not clear. In an effort to learn more regarding a possible mechanism of action, the susceptibility of protein-bound amino acids to enzymatic attack by myeloperoxidase (MPO) in the presence of chloride ions was investigated. [1, 7-14C]diaminopimelic acid (DAP) was incorporated into Escherichia coli W-7 proteins with little randomization of the radioactivity. Under appropriate conditions, it was observed that the MPO-H2O2-halide system released approximately 94% of the radioactivity from labeled bacteria. This would indicate that, in addition to decarboxylation, peptide bonds are also split during this reaction. The oxidative decarboxylation of DAP-labeled bacteria by MPO (i) is Cl− dependent, (ii) has an acid pH optimum, (iii) requires a specific concentration of H2O2 for activity, (iv) reaches a plateau by 25 min, and (v) is markedly inhibited by taurine. These properties are similar to those observed with free amino acids. It appears from these data that MPO can not only decarboxylate free and bound amino acids, yielding aldehydes, but also it can actively participate in oxidative peptide cleavage. Both of those activities may play a critical role in the microbicidal action of the leukocyte.
87 citations
TL;DR: Property of the synthesis and cleavage reactions and the exchange of carboxyl group of glycine with bicarbonate are presented and leads to the isolation of a nearly homogeneous form of T-protein but P-protein still is heterogeneous.
85 citations
TL;DR: In this paper, it was shown that the ureido-N position of biotin is the site of carboxylation, rather than the UREido-O, of the imidazolidone ring.
80 citations
TL;DR: Evidence for the mediation of C4 acid decarboxylation in this group by an NAD malic enzyme located in bundle sheath mitochondria is provided and a detailed scheme is proposed to account for decar boxylation of aspartate derived from mesophyll cells.
Abstract: C4 acid decarboxylation in many C4-pathway species is accounted for either by an NADP-specific malic enzyme or phosphoenolpyruvate carboxykinase but a major group lack these enzymes. The present paper provides evidence for the mediation of C4 acid decarboxylation in this group by an NAD malic enzyme located in bundle sheath mitochondria. This enzyme was most active with NAD and Mn2+ and, depending upon its source, activity was stimulated 5- to 15-fold by low con- centrations of CoA or acetyl-CoA. The activity in leaf extracts was 20-50 times that found in other groups of C4 species or in C3 species and was commensurate with the enzyme having an integral function in photosynthesis. For most species showing high NAD malic enzyme activity there was little activity when Mg2+ replaced Mn2+ and the low activity recorded with NADP was not activated by CoA or acetyl-CoA. In others there was an activator-dependent rate with NADP equivalent to 25-30% of the rate with NAD. Evidence for the location of the NAD malic enzyme in bundle sheath mitochondria is provided. On the basis of these and earlier studies a detailed scheme is proposed to account for decarboxylation of aspartate derived from mesophyll cells.
73 citations
TL;DR: Endor spectroscopy was used to identify three primary radicals in single crystals of histidine hydrochloride x irradiated at 4.2°K as mentioned in this paper, and was also used to characterize more completely the final hydrogen-adduct radical that was obtained on warming the crystals to room temperature.
Abstract: ENDOR spectroscopy was used to identify three primary radicals in single crystals of histidine hydrochloride x irradiated at 4.2°K. Oxidation leads to decarboxylation producing the radical R–CH2–CH–NH3+, where R stands for the protonated imidazole ring. Another oxidation product is produced by removal of an electron from the imidazole ring. The reduction process yields a carboxyl anion by addition of an electron to the carbonyl oxygen. ENDOR spectroscopy was also used to characterize more completely the final hydrogen‐adduct radical that is obtained on warming the crystals to room temperature.
TL;DR: In this article, the metal-catalyzed reaction of 1,1′-carbonyldipyrazoles with aldehydes or ketones to give 1, 1′-alkylidenedipydrugs and carbon dioxide, the latter being derived from the amide carbonyl group as shown by labeling experiments, is sensitive to electronic and to steric substituent effects.
Abstract: The metal-catalyzed reaction of 1,1′-carbonyldipyrazoles with aldehydes or ketones to give 1,1′-alkylidenedipyrazoles and carbon dioxide, the latter being derived from the amide carbonyl group as shown by labeling experiments, is sensitive to electronic and to steric substituent effects. Under comparable reaction conditions, 1,1′-carbonyldiimidazole, N-acetylpyrazole, and 1-pyrazole-N,N-diethylcarbonamide do not react with acetone while pyrazole-1-carbo(N′-phenylhydrazide) yields an anilino isocyanate dimer. These results are interpreted in terms of a mechanism that involves coordination of the metal ion at the 2,2′-nitrogen atoms of the pyrazole rings and heterolytic cleavage of an amide bond, followed by formation of a carbamate intermediate, decarboxylation, and metal ion exchange. Unsymmetrically substituted 1,1′-carbonyldipyrazoles were found to equilibrate thermally with their respective symmetrical analogs by an intermolecular exchange mechanism.
TL;DR: It appeared that plaque organisms were capable of producing large amounts of amines from these amino acids and it is possible that the decarboxylation of amino acids may take place in plaque with the effect of offsetting the low pH values brought about by glycolytic bacteria.
TL;DR: Investigation of the lipid structures obtained from the Indigo snake suggest a biogenetic relationship whereby palmitic and palmitoleic acids are extended in chain length mainly to 32 and 34 carbonatom fatty acids, which could yield structures corresponding with the methyl ketones and the related secondary alcohols.
Abstract: Cast skins of the Florida indigo snake (Drymarchon corais) yielded up to 8% chloroform: methanol-extractable lipid, which was found to contain methyl ketones (20%), free secondary alcohols (15%), free primary alcohols (30%), free cholesterol (15%), free fatty acids (5%), and hydrocarbons (5%). The hydrocarbons appeared to be contaminants, because gas chromatography revealed a distribution characteristic of petroleum hydrocarbons. The methyl ketones were predominantly monounsaturated, with double bonds almost exclusively in the ω7 position. The structures of the secondary alcohols corresponded with the methyl ketones in regard to chain length distribution, location of the oxygen function in the 2 position, and the proportion and position of unsaturation. The primary alcohols were also predominantly straight, odd-carbon, unsaturated compounds, with ω7 double bonds, but with chain lengths principally of 29 and 31 carbon atoms. The free fatty acids were mainly even-carbon monounsaturated compounds of 16–20 carbon atoms with double bonds mainly in the Δ9-position. Inspection of the lipid structures obtained from the Indigo snake suggest a biogenetic relationship whereby palmitic and palmitoleic acids are extended in chain length mainly to 32 and 34 carbonatom fatty acids. Retention or introduction of an oxygen function in the 3 position, followed by decarboxylation, could then yield structures corresponding with the methyl ketones and the related secondary alcohols. Insertion of an oxygen atom between carbons 2 and 3 of the methyl ketones, followed by loss of the two carbon atoms thereby isolated from the chain, would produce the series of odd-carbon primary alcohols that were observed.
TL;DR: Alkane formation by the cell free preparation was also inhibited by parachloromercuribenzoate, dithioerythritol, ethylenediamine tetraacetate, and o-phenanthroline, suggesting this hydroxy acid is suggested to be an intermediate in the conversion of C 32 acid to C 31 alkane.
TL;DR: In vivo incorporation of [1-14C]lignoceric acid and [3H]lignment acid into the very long chain fatty acids and into the alkanes of Allium porrum L. wax shows that the following pathway is involved: Both elongation and decarboxylation take place in the epidermis cell.
TL;DR: In pyruvate carboxylation, SO 3 2− is inhibiting in a fully competitive manner as had been found in ribulose-diphosphateCarboxylase and phosphoenolpyruvates carboxyase.
TL;DR: The results clearly demonstrate direct decarboxylation as well as elongation and decar boxylation of exogenous fatty acids, and thus constitute the most direct evidence thus far obtained for an elongation-decarboxyation mechanism for the biosynthesis of alkanes.
Abstract: The structure and composition of the cutin monomers from the flower petals of Vicia faba were determined by hydrogenolysis (LiAlH4) or deuterolysis (LiAlD4) followed by thin layer chromatography and combined gas-liquid chromatography and mass spectrometry. The major components were 10, 16-dihydroxyhexadecanoic acid (79.8%), 9, 16-dihydroxyhexadecanoic acid (4.2%), 16-hydroxyhexadecanoic acid (4.2%), 18-hydroxyoctadecanoic acid (1.6%), and hexadecanoic acid (2.4%). These results show that flower petal cutin is very similar to leaf cutin of V. faba. Developing petals readily incorporated exogenous [1-14C]palmitic acid into cutin. Direct conversion of the exogeneous acid into 16-hydroxyhexadecanoic acid, 10, 16-dihydroxy-, and 9, 16-dihydroxyhexadecanoic acid was demonstrated by radio gas-liquid chromatography of their chemical degradation products. About 1% of the exogenous [1-14C]palmitic acid was incorporated into C27, C29, and C31n-alkanes, which were identified by combined gas-liquid chromatography and mass spectrometry as the major components of the hydrocarbons of V. faba flowers. The radioactivity distribution among these three alkanes (C27, 15%; C29, 48%; C31, 38%) was similar to the per cent composition of the alkanes (C27, 12%; C29, 43%; C31, 44%). [1-14C]Stearic acid was also incorporated into C27, C29, and C31n-alkanes in good yield (3%). Trichloroacetate, which has been postulated to be an inhibitor of fatty acid elongation, inhibited the conversion of [1-14C]stearic acid to alkanes, and the inhibition was greatest for the longer alkanes. Developing flower petals also incorporated exogenous C28, C30, and C32 acids into alkanes in 0.5% to 5% yields. [G-3H]n-octacosanoic acid (C28) was incorporated into C27, C29, and C31n-alkanes. [G-3H]n-triacontanoic acid (C30) was incorporated mainly into C29 and C31 alkanes, whereas [9, 10, 11-3H]n-dotriacontanoic acid (C32) was converted mainly to C31 alkane. Trichloroacetate inhibited the conversion of the exogenous acids into alkanes with carbon chains longer than the exogenous acid, and at the same time increased the amount of the direct decarboxylation product formed. These results clearly demonstrate direct decarboxylation as well as elongation and decarboxylation of exogenous fatty acids, and thus constitute the most direct evidence thus far obtained for an elongation-decarboxylation mechanism for the biosynthesis of alkanes.
TL;DR: Data are consistent with the conclusion that the enzyme-bound product is an intermediate in the reversible glycine cleavage reaction, and a scheme is presented for the reactions catalyzed by the enzyme system.
TL;DR: The results of the study indicate that as the plasma and tissue levels of tyrosine are elevated, decarboxylation to tyramine becomes the predominant route of metabolism.
Abstract: Metabolism of tyrosine was examined in mice, some of which had been treated with an inhibitor of aromatic-L-amino-acid decarboxylase. The results of the study indicate that as the plasma and tissue levels of tyrosine are elevated, decarboxylation to tyramine becomes the predominant route of metabolism. At the highest dose of tyrosine used (1.5 g/kg), it was found that 42% of the administered dose was decarboxylated within 6 hr and only 11.5% was metabolized by the tyrosine aminotransferase pathway.
TL;DR: In this paper, the reaction of dimethyl acetylendicarboxylate with hydrazinen oder Alkyl hydrazonen gives the methyl 1-alkyl-3-hydroxy-5-pyrazolecarboxylats 9 and 13a-e, subsequent saponification and decarboxylication gives the 1alkyl 3-hydroxypyrazoles 11 and 15a−e, the cyclization of 13f to lactone 19a is a structure proff.
Abstract: Durch Umsetzung von Acetylendicarbonsaure- dimethylester mit Hydrazinen oder Alkyl-hydrazonen erhalt man die 1-Alkyl-3-hydroxy-5-pyrazolcarbonsaure-methylester 9 und 13a–e, durch Verseifung und Decarboxylierung hieraus die 1-Alkyl-3-hydroxypyrazole 11 und 15a–e. Die Cyclisierung von 13f zum Lacton 19a ist strukturbeweisend. Bei Verwendung von Benzaldehyd-hydrazonen entstehen hauptsachlich 2-Pyrazolin-4,5- dicarbonsaureester.
Enehydrazines, 9. 1-Alkyl-3-hydroxypyrazoles from Hydrazones or Hydrazines
Reaction of dimethyl acetylendicarboxylate with hydrazinen oder Alkyl hydrazonen gives the methyl 1-alkyl-3-hydroxy-5-pyrazolecarboxylats 9 and 13a–e, subsequent saponification and decarboxylation gives the 1-alkyl-3-hydroxypyrazoles 11 and 15a–e. The cyclization of 13f to lactone 19a is a structure proff. Starting from benzaldehyde hydrazones, 2-pyrazoline-4,5-dicarboxylic esters are the main products.
TL;DR: The present studies with Atriplex spongiosa demonstrate the capacity of isolated mitochondria and bundle sheath cell strands to decarboxylate malate at rates commensurate with an integral role in photosynthesis.
TL;DR: Radio-chemical and spectral assays show that the activity of the complex in the absence of acetyl-CoA is about 25–30% of the activity in the presence of this compound, and it is proposed that decarboxylation of the malonyl moiety bound covalently to 4′-phosphopantetheine occurs to yield acetyl.
TL;DR: Observations support the view that the site of inhibition by ascorbate of oxygen reduction by chloroplast lamellar systems in the presence of ferredoxin is not identical with either the reducing side of photosystem I, fer redoxin or NADP-ferredoxin reductase.
Abstract: Ferredoxin-stimulated photosynthetic oxygen reduction and concommitant decarboxylation of glyoxylate by chloroplast lamellar systems is inhibited by ascorbate but ferredoxin dependent NADP⁺-reduction is not. In the presence of low potential electron acceptors (AQ or MV) this influence of ascorbate on glyoxylate decarboxylation by chloroplast lamellar systems is no longer observed.Using the diaphorase activity of NADP-ferredoxin reductase either bound to the chloroplast lamellar system or as an isolated enzyme fraction glyoxylate decarboxylation in the dark can be observed in the presence of NADPH + H⁺ and autooxidizable electron acceptors (AQ, MY, fer redoxin). The influence of ascorbate on this dark reaction, depends on whether the activity of the isolated or the lamellae-bound enzyme is measured:1. With the isolated enzyme no influence of ascorbate on AQ-, MV-or ferredoxin-stimulated glyoxylate decarboxylation is observed.2. The dark-reaction with NADPH + H⁺ as electron donor, catalyzed by the bound enzyme however is inhibited by ascorbate both in the presence of either ferredoxin or AQ. This and other observations support the view that the site of inhibition by ascorbate of oxygen reduction by chloroplast lamellar systems in the presence of ferredoxin is not identical with either the reducing side of photosystem I, ferredoxin or NADP-ferredoxin reductase. The site of inhibition by ascor bate is more likely connected with an additional pathway involved in photosynthetic oxygen re duction by chloroplast lamellar systems, which is located at the reducing side of photosystem I, i. e. in the vicinity of the NADP-ferredoxin reductase. By heat treatment of isolated chloroplast lamellar systems a factor is released showing the activity of an ascorbate-sensitive oxygen reductant upon illumination in the presence of chloroplast lamellar systems. A model for photosynthetic oxygen reduction is proposed which includes ferredoxin and a membrane-bound oxygen reductant in series. Oxygen reduction by this pathway is only operating when the available NADP is fully reduced
TL;DR: In this article, the preparation and characterization of the stable alkylcopper (I), cyanomethylcopper(I), via ready decarboxylation of CuI and CuII cyanoacetates are reported.
Abstract: The preparation and characterization of the stable alkylcopper(I), cyanomethylcopper(I), via ready decarboxylation of CuI and CuII cyanoacetates are reported.