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1.
The employment of periodate oxidation in the chemistry of nucleic acids and their components is reviewed. The reaction mechanism, structural requirements to substrates, and synthesis of dialdehyde derivatives of nucleosides, nucleotides, and oligonucleotides are discussed in the first part. The second part involves chemical, physico-chemical, and biological properties of the dialdehyde derivatives, as well as their use for the affinity modifications of proteins.  相似文献   

2.
The biosynthesis of chrysomelidial and plagiodial was studied in the rove beetle subtribe Philonthina (Staphylinidae). Glandular homogenates were found to convert synthetic (2E,6E)-[trideuteromethyl-5,5-(2)H(5)]octa-2,6-diene-1,8-diol (10) into nor-chrysomelidial (14) and nor-plagiodial (13). The overall transformation requires; i) oxidation of the substrate at C(1) and C(8), ii) cyclization of the resulting dialdehyde to nor-plagiodial followed by iii) isomerization to give nor-chrysomelidial. The oxidase requires molecular oxygen as a cofactor and operates with removal of the pro-R hydrogen from C(1) and C(8) of synthetic (1R,8R,2E,6E)-[1,8-(2)H(2)]-2,6-dimethyl-octa-2,6-diene-1,8-diol (15), producing a dialdehyde along with H(2)O(2). Unlike enzymes from iridoid-producing leaf beetle larvae, the Philonthus enzyme is able to oxidize saturated substrates such as citronellol. Crude protein extracts prepared from Philonthus glands by ammonium sulfate precipitation, were found to produce hydrogen peroxide at a rate of 0.085+/-0.003 ng H(2)O(2) (ng protein)(-1) hr(-1) with nerol as an oxidase substrate. The cyclase operates with opposite stereochemistry to the enzyme(s) from Phaedon cochleariae and other herbivorous leaf beetles, specifically removing the C(5)-H(R) hydrogen atom from (4R,5S,2E,6E)-[4,5-(2)H(2)]-2-methyl-octa-2,6-diene-1,8-diol (17). These findings have enabled us to construct a detailed account of iridoid biosynthesis in rove beetles, which resembles the biosynthetic route in leaf beetle larvae, but exhibits distinct stereochemical differences.  相似文献   

3.
The component aldehydes in dialdehyde fragments formed by periodate oxidation of oligosaccharides were converted quantitatively into the corresponding (2,4-dinitrophenyl)hydrazones by the simple procedure of treatment with excess (2,4-dinitrophenyl)hydrazine hydrochloride in 1,2-dimethoxyethane. Then, by chromatographic separation of the hydrazones on a small column of silica gel and subsequent spectrophotometric analysis, it was possible to determine the position of glycosidic substitution in μmolar amounts of various types of glucobioses, oligosaccharides of senega, and some synthetic (1→6)-β-D-gluco-oligosaccharides.  相似文献   

4.
S-Adenosylhomocysteine hydrolase (AdoHcy hydrolase, E.C. 3.3.1.1) catalyzes the metabolism of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and homocysteine (Hcy) in mouse neuroblastoma N2a cells. AdoHcy hydrolase in N2a cells can be inhibited completely by adenosine dialdehyde (Ado dialdehyde) or neplanocin A. The inhibitory effects of Ado dialdehyde (2.5 μM) and neplanocin A (1 μM) on cellular AdoHcy hydrolase were time-dependent, with total enzyme inhibition occurring after 30 min and 15 min of incubation, respectively. The inhibition of AdoHcy hydrolase produced by Ado dialdehyde and neplanocin A persisted for up to 72 h of incubation, and was paralleled by a time-dependent increase in endogenous AdoHcy levels reaching a maximum 4-fold elevation after 8 h of incubation with Ado dialdehyde and an 11-fold increase in the neplanocin A-treated cells. This increase in AdoHcy levels produced a subsequent inhibition of S-adenosylmethionine (AdoMet)-dependent cellular methylations (e.g. protein carboxylmethylation (PCM), lipid methylation). In addition, neplanocin A was metabolically converted to the corresponding AdoMet analog, S-neplanocylmethionine (NepMet), in neuroblastoma N2a cells. NepMet reached maximum levels after 8 h of incubation of the cells with neplanocin A.  相似文献   

5.
S-Adenosyl-L-homocysteine (SAH) was converted to 2′-O-[(R)-formyl(adenin-9-yl)methyl]-3′-S-homocysteinyl-3′-deoxy-(R)-glyceraldehyde (SAH dialdehyde) by periodic acid oxidation. SAH dialdehyde was then reduced with sodium borohydride to the corresponding diol, 2′,3′-acyclic SAH. SAH dialdehyde, but not 2′,3′-acyclic SAH, was found to inhibit histamine-N-methyltransferase (HMT). Neither analog showed significant inhibitory activity toward other methyltransferases. The inhibition of HMT by SAH dialdehyde was irreversible with the inactivation following first-order kinetics. A kinetic analysis suggests the formation of a dissociable enzyme-inhibitor complex prior to inactivation. The enzyme could be protected from inactivation by inclusion of S-adenosyl-L-methionine in the preincubation mixture.  相似文献   

6.
(1) Periodate oxidation of ATP yields a single product which has been purified and characterised. Periodate-oxidised ATP (o-ATP) behaves as a single compound during TLC analysis, but NMR spectral studies show that it exists in aqueous solution as an equilibrium mixture of three dialdehyde monohydrates and a dihydrate. Little free aldehyde is present. The dialdehyde monohydrates are in the form of diastereomeric cyclic hemiacetals. (2) The dialdehyde grouping of o-ATP can be reduced with sodium borohydride, producing a dialcohol. (3) o-ATP has been frequently used in attempts to affinity label nucleotide-binding sites on proteins. The proposed structure of o-ATP is discussed in relation to this use for o-ATP.  相似文献   

7.
A study was made of the influence of rheopolyglucin and dextran dialdehyde derived therefrom on the structural characteristics and thermostability of human hemoglobin. The effects of solution pH, incubation time and temperature, and the degree of dextran oxidation on the conjugation between human hemoglobin and dextran dialdehyde were assessed. Formation of the hemoglobin-dextran dialdehyde complex resulted in shielding of the protein chromophore groups by the polysaccharide and transition of a part of hemoprotein molecules from a low-spin (HbO2) to a high-spin (Hb and MetHb) state. It was found that the temperature of denaturation transition for the native protein and hemoglobin in the presence of rheopolyglucin was 60°C versus 80°C for the hemoprotein-dextran dialdehyde conjugate. Presumably, the latter is determined by the enhancement of hydrophobic interactions within the protein globule caused by dextran dialdehyde and the ability of the surface-bound carbohydrate components to prevent the association of hemoglobin molecules.  相似文献   

8.
Deoxyadenosine (dAdo) and deoxyguanosine (dGuo) decrease methionine synthesis from homocysteine in cultured lymphoblasts; because of the possible trapping of 5-methyltetrahydrofolate this could lead to decreased purine nucleotide synthesis. Since purine deoxynucleosides could also inhibit purine synthesis de novo at an early step not involving folate metabolism, we measured in azaserine-treated cells 5-amino-4-imidazolecarboxamide (Z-base)-dependent purine nucleotide synthesis using [14C]formate. In the T lymphoblasts, Z-base-dependent purine nucleotide synthesis was decreased 26% by 0.3 microM-dAdo, 21% by 1 microM-dGuo and 28% by 1 microM-adenosine dialdehyde, a potent S-adenosylhomocysteine hydrolase inhibitor; homocysteine fully reversed the inhibitions. The B lymphoblasts were considerably less sensitive to the deoxynucleoside-induced decrease in Z-base-dependent purine nucleotide synthesis, with 100 microM-dAdo required for significant inhibition and no inhibition by dGuo at this concentration; homocysteine partly reversed the inhibition by dAdo. The observed decrease in Z-base-dependent purine nucleotide synthesis could not be attributed either to dUMP depletion changing the folate pools or to decreased ATP availability because dUrd was without effect and during the experimental period the intracellular ATP concentration did not change significantly. Cells with 5,10-methylenetetrahydrofolate reductase deficiency were relatively resistant to inhibition of Z-base-dependent purine nucleotide synthesis by dAdo and adenosine dialdehyde. Our results suggest that deoxynucleosides decrease purine nucleotide synthesis by trapping 5-methyltetrahydrofolate.  相似文献   

9.
Gossypol, a polyphenolic binaphthyl dialdehyde found in cotton seeds, is a dietary mutagen and a potential male contraceptive. In the presence of Cu(II), gossypol caused breakage of supercoiled plasmid pBR322 DNA. The products were relaxed circles or a mixture of these and linear molecules. Other metal ions tested [Ni(II), Co(II), Mn(II), and Fe(II)] were ineffective or less effective in the DNA breakage reaction. In the case of gossypol-Cu(II) mediated cleavage, (Cu(I) was shown to be an essential intermediate by using the Cud) sequestering reagent bathocuproine. By using job plots, it was established that in the absence of DNA, eight Cu(II) ions can be reduced by one gossypol molecule. The involvement of active oxygen species, such as singlet oxygen and H2O2, was established by the inhibition of DNA breakage by catalase and by sodium azide. It was further shown that gossypol is capable of directly producing H2O2.  相似文献   

10.
The possibility was examined that the membrane function of erythrocytes obtained from healthy common marmosets (Callithrix jacchus) was modified by the presence in the cells of Heinz bodies. No significant differences were found in erythrocyte endogenous free malonyl dialdehyde (MDA) or reduced glutathione (GSH) between normal human erythrocytes and marmoset erythrocytes containing Heinz bodies. Membrane fluorescent chromolipids, surface charge and thiol levels were similar in both species but average membrane bulk lipid fluidity was slightly elevated in the marmosets. It was concluded that, in contrast to the situation in human erythrocytes, the presence of Heinz bodies in red cells of marmosets does not adversely affect the properties of the membrane.  相似文献   

11.
It is established, that low doses of X-ray irradiation have affected activation of lipid peroxidation (LPO) in immunocompetent cells of the spleen and thymus. The amount of malonic dialdehyde (MDA) in lymphocytes of spleen and thymocytes increases 2 times twenty-four hours after animals' irradiation by X-rays in a dose of 0.5 Gy; when a dose grows to 1.0 Gy, the MDA content in the spleen lymphocytes increases from the 1st to the 6th days and in thymocytes from the 1st to the 3d days reaching its maximum at the 3d day. MDA accumulation in the immunocompetent cells of irradiated animals varies depending on the method of lipid peroxidation initiation.  相似文献   

12.
Malondialdehyde (MDA), a byproduct of non-enzymatic lipid peroxidation and prostaglandin biosynthesis, has been shown to be a weak frameshift mutagen in Salmonella mutagenicity assays. Because it is a dialdehyde, MDA can undergo self condensation to form polymeric products. It is possible that these condensation products are highly mutagenic and have contributed to previously reported estimates of MDA mutagenicity. We synthesized two major MDA polymerization products, (1) 2-(3'-oxo-1'-propenyl)-malondialdehyde [(MDA)2] and (2) 2,4-dihydroxymethylene-3-(2,2-dimethoxyethyl)glutaraldehyde [(MDA)3Me2] and tested their mutagenicity in the Salmonella frameshift tester strains hisD3052 and TA94 (hisD3052/pKM101). Analysis of the reversion rates revealed both (MDA)2 and (MDA)3Me2 to be weak mutagens, approximately equipotent to MDA. Although both (MDA)2 and (MDA)3Me2 are mutagenic, the fact that their formation is thermodynamically unfavorable under physiological conditions suggests they do not contribute significantly to the mutagenicity of MDA solutions.  相似文献   

13.
Various ribonucleoside 2',3'-dialdehydes, including adenosine dialdehyde, S-adenosylhomocysteine (AdoHcy) dialdehyde, and 5-(methylthio)-5'-deoxyadenosine (MTA) dialdehyde, were shown to be potent inhibitors of bovine liver AdoHcy hydrolase (EC 3.3.1.1). These ribonucleoside 2',3'-dialdehydes produce both time-dependent and concentration-dependent inactivation of the AdoHcy hydrolase. The inactivation appears to be irreversible since the enzyme activity cannot be recovered after prolonged dialysis against phosphate buffer. However, a substantial percentage of the enzyme activity could be recovered when the inactivated enzyme was dialyzed against a nitrogen buffer [e.g., tris(hydroxymethyl)aminomethane (Tris)]. This reversal of inhibition could be prevented, however, by pretreatment of the ligand-enzyme complex with sodium borohydride prior to dialysis in Tris buffer. Inclusion of substrates (e.g., adenosine or AdoHcy) afforded protection of the enzyme from the inactivation induced by the ribonucleoside 2',3'-dialdehydes. These data suggest that the bond formed between the enzyme and the inhibitor is probably a Schiff base linkage between the aldehydic functionality of the inhibitor and a protein lysinyl residue in or around the adenosine-AdoHcy binding site. When [2,8-3H]adenosine dialdehyde was used, a stoichiometry of 1.73 nmol of inhibitor bound per nmol of AdoHcy hydrolase was determined. Analysis of the kinetics of enzyme inactivation using the Ackermann-Potter approach indicates that adenosine dialdehyde is a tight-binding inhibitor, exhibiting a stoichiometry of one to two molecules of inhibitor bound to one molecule (tetramer) of enzyme and a Ki = 2.39 nM.  相似文献   

14.
Dialdehyde derivatives of cellulose (CE) and α-cyclodextrin (α-CD) were prepared by the periodate oxidation method. Linkage formation between cellulose dialdehyde (dial-CE) and bovine serum albumin (BSA) proceeded rapidly at pH 9.0 and gave a maximum yield at about 30 hr. Among the various amino compounds tested, ethylenediamine, hexylamine, hexamethylenediamine and BSA were bound effectively to the dial-CE in this order. As compared with the case of dial-CE, reactions between α-CD dialdehyde (dial-CD) and amino compounds proceeded rather slowly. Separation of dial-CD isomers linked with glycine by a DEAE-Sephacel column resulted in several peaks. However, the components of each fraction were not homogeneous. Reactions of dialdehyde derivatives with amino compounds were thought to produce a 4-oxa-azepine-type of complex.  相似文献   

15.
The hydrolysis of ethyl (R)-2-(benzyloxycarbonylamino)-3-sulfamoylpropionate (blocked cysteic acid S-amide) by native and immobilized alpha-chymotrypsin was studied. The experiments were performed using a constant enzyme/substrate ratio of 1:8 and at a temperature of 10-40 degrees C; the immobilized enzyme was bound to a dialdehyde cellulose matrix. A kinetic equation (Eq.10) was found to be applicable which confirms that the mechanism of the enzyme reaction consists of several stages, irrespective of the enzyme state. The temperature dependence of the reaction velocity was investigated and applied using the Arrhenius equation. The constant value thus obtained for the activating energy showed that the active centres retained their character during immobilization. The differences between the velocities of the reaction with immobilized and with native enzyme corresponded to the different number of active centres during the reaction time. Based on these results a kinetic model of the mechanism of the studied reaction is presented which includes an initial balanced stage of the chemosorption type.  相似文献   

16.
Upon extensive purification of the serum-free supernatant produced by a mutant T cell line (6T-CEM), an immunosuppressive activity was found to reside in an oxidized product of spermine, spermine dialdehyde (SDA). The activity was purified to homogeneity from a serum-free supernatant by using gel filtration chromatography and reverse-phase C18 HPLC. Fast Atom Bombardment (FAB) mass spectral analysis revealed its MW to be 202 and Electron Impact (EI) analysis of the acetylated material identified the purified molecule to be spermine. In the presence of human or rodent plasma, spermine exhibited no immunosuppressive activity up to 2 mg/ml. However, when assayed in the presence of FCS, which contains polyamine oxidase (PAO), spermine is oxidized to its corresponding dialdehyde which is active at 0.1 microM/ml. We have previously described a high molecular weight suppressor activating factor (SAF) found in the serum-containing supernatant of the 6T-CEM cell line. Our preliminary biological data suggest that SDA is probably responsible for the immunosuppressive activities previously observed for the SAF. The strong affinity of SDA for proteins and thiocompounds may account for the apparent high MW previously reported for SAF.  相似文献   

17.
Screen-printed carbon electrodes modified with the dialdehydes, glutaraldehyde and terephthaldicarboxaldehyde, and then polyethyleneimine have been utilized for production of pesticide biosensors based on acetylcholinesterase. To improve the extent of dialdehyde modification, the electrodes were NH2-derivatized, initially by electrochemical reduction of 4-nitrobenzenediazonium to a nitroaryl radical permitting attachment to the carbon surface. Subsequent reduction of the 4-nitrobenzene yields a 4-aminobenzene modified carbon surface. Drosophila melanogaster acetylcholinesterase was immobilized either covalently onto dialdehyde modified electrodes or non-covalently onto polyethyleneimine modified electrodes. Internal diffusion limitations due to the dialdehyde and polyethyleneimine modifications increased the apparent Km of the immobilized enzyme. The thiocholine sensitivity was about 90% for dialdehyde modified electrodes and about 10% for polyethyleneimine modified electrodes as compared with non-modified carbon electrodes. The detection limit of the biosensors produced by non-covalent immobilization of acetylcholinesterase onto polyethyleneimine modified carbon electrodes was found to be about 10(-10) M for the organophosphate pesticide dichlorvos.  相似文献   

18.
The regulatory site(s) responsible for ADP-induced hysteretic inhibition of pig heart mitochondrial F1-ATPase appeared to be specific of adenine nucleotides. The site(s) cannot be readily occupied by guanosine analogues although GTP is hydrolyzed at the catalytic sites. The length of the phosphate chain must be that of a nucleoside-diphosphate. Adenosine β,γ-imidotriphosphate, dialdehyde derivative of ADP also bind to the site(s) while ribosering opened analogues do not. It is also demonstrated that saturation of only one site, specifically by ADP, might be sufficient to induce hysteretic inhibition. However it cannot be excluded that other site(s), less specific, must also be saturated by nucleotides to permit ADP-inhibitory effects.  相似文献   

19.
Ortho-phthalaldehyde (OPA) is a new aromatic dialdehyde antimicrobial agent, the mechanism of action of which has been little studied. The aims of this paper are to examine what is currently known about its mechanism of action, to compare the action with that of a widely investigated aliphatic dialdehyde, glutaraldehyde (GTA), and to put forward a hypothesis that would, in the light of current knowledge, explain how OPA inactivates micro-organisms, including GTA-resistant Mycobacterium chelonae.  相似文献   

20.
A procedure for preparing derivatives of dialdehyde dextran-glass-carriers and their use for immobilization of trypsin is described. The dextran to the support as well as the trypsin to dextran were covalently immobilized via dialdehyde groups. The relative activity of immobilized trypsin in these enzyme-carrier-complexes amounted 17.3% and 20,4 (determined with alpha-N-Benzoyl-DL-arginine-p-nitroanilid) and 8,2% and 11.6% (determined with casein).  相似文献   

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