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1.
Summary The activity of poly (ADP-ribose) polymerase (ADPRP) and the content of 2,5-oligodenylates core (2,5An; n = 2,3 and 4) were measured in homogenates of the uterus and of the liver of immature rats immediately before (time 0) or at different times after injection of estradiol-valerate. ADPRP activity increased gradualy, starting 6 hours after estrogen injection, for about 4 days. Instead, the content of 2,5 An decreased by about 50% within 6 hours, and thereafter more slowly for 4 days to about 20% of starting values. Estrogen increased ADPRP activity and decreased 2,5An concentration also in the kidney and in the cardiac muscle of the same animals, but not in the skeletal muscle, where neither of the two parameters was affected. Injection of vehicle only (sesame oil) had no effect on ADPRP activity nor on 2,5An content of immature rat tissues.  相似文献   

2.
Summary The actions of cyclic AMP are subject to several levels of post-receptor modulation in cardiac tissue. Isoproterenol and prostaglandin E1 both stimulate cAMP accumulation, but only isoproterenol causes activation of particulate cAMP-dependent protein kinase, leading to activation of phosphorylase kinase and glycogen phosphorylase, and inhibition of glycogen synthase. Through the use of isolated, adult ventricular myocytes, we have determined that the hormone-specific activation of glycogen phosphorylase is due to subcellular compartmentation of cAMP. There is some evidence that cyclic nucleotide phosphodiesterases, whose activity is stimulated by alpha1-adrenergic agonists in isolated myocytes, may have a role in compartmentation. Phosphoinositide hydrolysis is stimulated by alpha, and muscarinic agonists, presumably leading to activation of protein kinase C, which in turn has multiple effects on hormone-sensitive adenylate cyclase.Abbreviations cAMP Adenosine-3,5-Cyclic Monophosphate - cGMP Guanosine-3,5-Cyclic Monophosphate - Gi, GS Guanine nucleotide-binding proteins linked to inhibition and stimulation, respectively, of adenylate cyclase - GTP Guanosine-5-triphosphate - PDE Cyclic Nucleotide Phosphodiesterase - PGE1 Prostaglandin E1  相似文献   

3.
The reaction of the 5-AMP with water soluble carbodiimide (EDAC) in the presence of Na+-montmorillonite 22A results in the formation of 2,5-(pA)2 (18.9%), 3,5-(pA)2 (11%), and AppA (4.8%). When poly(U) is used in place of the clay the product yields are 2,5-(pA)2 (15.5%), 3,5-(pA)2 (3.7%) and AppA (14.9%). The 3,5-cyclic dinucleotide, 3,5-c(pA)2, is also formed when poly(U) is used. AppA is the principal reaction product when neither clay nor poly(U) is present in the reaction mixture. Products which contain the phophodiester bond are formed at different ionic strengths, pH and temperatures using Na+-montmorillonite. Phosphodiester bond formation was not observed when Cu2+-montmorillonite was used or when DISN was used in the place of EDAC. The extent catalysis of phophodiester bond formation varied with the particular clay mineral used. Those Na+-clays which bind 5-AMP more strongly are better catalysts. Cu2+-montmorillonite, which binds 5-AMP strongly, exhibits no catalytic activity.  相似文献   

4.
Summary d(-)-lactate dehydrogenase from hybrid male strain of Allomyces has been partially purified.The enzyme shows multiple binding sites for NADH. It obeys Michaelis-Menten kinetics for pyruvate. The inhibition of the enzyme activity by ATP is of mixed type. ADP is not an allosteric inhibitor of the enzyme. AMP and cyclic 3,5-AMP do not affect the enzyme. NAD+ acts as a product inhibitor.  相似文献   

5.
This report summarizes structure/activity investigations on 3-O-substituted adenine nucleotides derived from 3-O-naphthoyl-ADP. Among these are fluorescent nucleotides, which allow one to differentiate between two types of binding sites on the inner surface of the mitchondrial inner membrane. One type of site is highly fluorescent but is not located on F1. It is attributed to the nucleotide carrier, because it stays on the membrane when F1 is removed. The other type of sites, giving no or only very low fluorescence, is located on F1 and shows high affinity to these analogs, which is modulated by the energy state of the membrane. On the basis of kinetic data, stability of magnesium complexes, and fluorescence properties, conclusions are drawn on the probable conformation of these nucleotides in the bound state. They allow one to explain why these nucleotide analogs are extremely strong inhibitors of oxidative phosphorylation and photophosphorylation, why the ADP derivatives cannot be phosphorylated, and why the ATP analogs are no substrates of ATPase. Furthermore, the results allow some insight into the mechanism of phosphorylation and the structural properties at the catalytic site.Abbreviations AP5A 5,5-diadenosinepentaphosphate - SMP submitochondrial particles - F-AD(T,M)P fluorescent AD(T,M)P = 3-O-(5-dimethylaminonaphthoyl-1)-AD(T,M)P - FCCP carbonylcyanide 4-trifluoromethoxyphenylhydraxone  相似文献   

6.
Human fragile histidine triad (FHIT) protein has dinucleoside 5,5-P1,Pn-polyphosphates hydrolysis activity, with AMP being one of the reaction products. Application of synchronous luminescence (SL) spectroscopy, in which both excitation and emission wavelengths are scanned simultaneously while a constant wavelength interval is maintained between them, was investigated for detection of the enzymatic activity of the FHIT protein. Ability of SL to identify reaction components, AMP production and its increase as a result of increase in substrate concentration and inhibition of the hydrolysis activity by ZnCl2 are demonstrated.  相似文献   

7.
Rabbit anti-mouse-Ia serum was raised against Ia specificities present in CBAJH (H-2 k) serum. This xenogeneic antiserum was considered to react with similar specificities to those detected by mouse anti-Iak alloantisera and more evidence is now presented for this contention. By absorption, the xenogeneic antiserum was found to react with spleen, lymph node, bone marrow, and thymus, reactions similar to that found with the allogeneic anti-Iak antiserum. Furthermore, red cells, platelets, brain, kidney, and liver could not absorb the activity from the xenogeneic antiserum, demonstrating the selective tissue distribution of the antigens reactive with this serum. This reactive population was previously shown to consist of B cells and a subpopulation of T cells. In a backcross study of (C57BL/6 × A)F1 × C57BL/6, the rabbit anti-Ia and mouse anti-Ia reactions were found to segregate together, and some evidence for the genetic regulation of the expression of Ia specificities was also found. By direct testing, and by absorption testing using a number of strains, the xenogeneic antiserum was shown to contain high titers of antibody to Ia.1, 3, 7, 15, and 17; lower titers to Ia.19, and 22; little antibody to Ia.18, and no reaction for the private specificity Ia. 2, although the multiple absorptions required to define these specificities may have observed some reactions. The data indicate that the xenogeneic and allogeneic anti-Iak antisera recognize similar Ia determinants, which map to theLA, IE andIC subregions of theH-2 complex. These have been given the same specificity designation as the allogeneic specificities, but they are separately identified by a prime (').  相似文献   

8.
Summary Organic pyrophosphates such as UppA and NAD are formed when a solution containing a nucleotide, a nucleoside 5-polyphosphate, Mg2+ and imidazole are allowed to dry out. We suggest that this synthesis may have occured concurrently with oligonucleotide formation.Abbreviations Im Imidazole - CDI 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride - EDTA ethylenediaminetetraacetic acid - A adenosine - U uridine - pnA adenosine 5-poly-phosphate containing n phosphate residues - pU uridine 5-phosphate - AppA P1,P2-diadenosine 5-pyrophosphate - UppA P1-(uridine 5)-P2-(adenosine 5)-pyrophosphate - ImpA adenosine 5-phosphorimidazolide - NMN nicotinamide mononucleotide - NAD nicotinamide-adenine dinucleotide  相似文献   

9.
Summary Crude cell-free extracts of Anabaena cylindrica synthesized adenosine-5-phosphosulphate (AP35S) and 3-phosphoadenosine-5-phosphosulphate (PAP35S) from 35SO4 2- in the presence of Mg2+, ATP and inorganic pyrophosphatase. Maximum AP35S and PAP35S were produced at pH 7.15 and 8.05, respectively. APS kinase was detected in the supernatant of crude cell-free extracts by a spectrophotometric procedure. ATP-Sulphurylase had an absolute requirement for Mg2+ and less than 30% AP35S was formed when Mg2+ was replaced by either Mn2+ or Co2+. Nucleotide triphosphates other than ATP and 2-deoxyATP were ineffective in this reaction. Maximum enzyme activity was observed at equimolar concentrations of Mg2+ and ATP and excess of either of these was inhibitory. Other nucleotide triphosphates, like GTP, UTP, CTP, TTP, ITP, or 2-deoxyATP also inhibited the enzyme activity. Inhibition by GTP was competitive with respect to ATP. ATP-sulphurylase activity was not affected by cysteine, methionine or glutathione.Abbreviations APS adenosine-5-phosphosulphate - PAPS 3-phosphoadenosine-5-phosphosulphate  相似文献   

10.
The effects of glycerol and methanol upon beef heart mitochondrial ATPase (F1) were studied. Glycerol was found to be a potent reversible inhibitor of the F1-catalyzed hydrolysis of ATP and ITP. The inhibition of ATP hydrolysis was linear with respect to glycerol concentrations, while that of ITP was not. From the temperature dependence ofV max for F1-catalyzed ATP and ITP hydrolysis in glycerol or methanol solutions, the energy of activation and the enthalpy of activation were calculated. The inhibitory effect of ADP on F1 hydrolytic activity was studied in three solvent systems (totally aqueous, 20% methanol, and 20% glycerol). Compared to the aqueous system, methanol decreased the potency of ADP as an inhibitor, and glycerol enhanced the potency.Abbreviations used: TEA, triethanolamine; PEP, phosphoenolpyruvate; ATP, adenosine-5-triphosphate; ITP, inosine-5-triphosphate; ADP, adenosine-5-diphosphate.  相似文献   

11.
Summary Inhibition of growth of PY815 mouse mastocytoma cells in vitro by N6, O2-dibutyryladenosine 3,5 cyclic monophosphate (DB cyclic AMP) was accompanied by increases in intracellular cyclic AMP and histamine and minor changes in cytosolic cyclic AMP-dependent histone kinase activity. However, DEAE-cellulose chromatography revealed substantial changes in the relative proportions of the principal cyclic AMP-dependent protein kinases and in free cyclic AMP-binding protein after DB cyclic AMP treatment. The activity of cytosolic cyclic AMP-dependent protein kinase type I (PKI) decreased relative to cyclic AMP-dependent protein kinase type II (PKII) and there was an increase in a cytosol cyclic AMP-binding protein with little associated protein kinase activity. The relative changes in activity of PKI, PKII and cyclic AMP binding protein after DB cyclic AMP treatment may reflect events important in the regulation of growth and differentiation of mast cells.Abbreviations DB cyclic AMP N6,O2-dibutyryladenosine-3, 5-cyclic monophosphate - cyclic AMP adenosine 3,5-cyclic monophosphate - PKI type I cyclic AMP-dependent protein kinase - PKII type II cyclic AMP-dependent protein kinase  相似文献   

12.
ATPase activity in rat heart sarcoplasmic reticulum was stimulated in a concentration-dependent manner by both Ca2+ and Mg2+ in the complete absence of the other cation. Increasing concentrations of Mg2+ produced an apparent inhibition of the Ca2+-dependent ATP hydrolysis. CDTA (trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetate) had no effect on these responses. The results indicate the presence of a low affinity non-specific divalent cation-stimulated ATPase in rat heart sarcoplasmic reticulum. However, sarcoplasmic reticulum vesicles transported Ca2+ with a high affinity (K0.5 Ca2+ = 0.41 M) suggesting the presence of a high affinity Ca2+-transporting ATPase. Calmodulin did not stimulate rat heart sarcoplasmic reticulum ATPase activity over a range of Ca2+ and Mg2+ concentrations and failed to stimulate membrane phosphorylation and Ca2+ transport into sarcoplasmic reticulum vesicles. Calmodulin antagonists trifluoperazine and compound 48180 did not affect the ATPase activity. Catalytic subunit of cAMP-dependent protein kinase was also ineffective in stimulating the ATPase activity. These results suggest the presence of an ATPase activity in rat heart sarcoplasmic reticulum with different properties from the high affinity Ca2+-pumping ATPase previously characterized in dog heart and other species.Abbreviations cAMP adenosine 3,5-monophosphate - CaM calmodulin - CDTA trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetate - EDTA ethylene-diaminetetraacetate - EGTA ethylene glycol bis(-aminoethyl ether)-N,N,N,N-tetraacetate - PLB phospholamban - SR sarcoplasmic reticulum - TFP trifluoperazine  相似文献   

13.
APS-kinase (ATP: adenylylsulphate 3-phosphotransferase, EC 2.7.1.25) has been purified from the alga Chlamydomonas reinhardii, strain CW 15 by means of chromatofocussing and affinity chromatography. The isolated protein showed an apparent molecular mass of 44,000 upon sodium dodecylsulphate polyacrylamide gel electrophoresis. The transfer of phosphate groups from ATP onto APS required a pH of 6.8, the presence of Mg2+ ions and a reducing thiol. Its catalytical activity was destroyed by sulphhydryl group inhibitors (phenyl-mercuri compounds, dithiopyridine) and alkylating reagents.The purified enzyme attained a V max of 360 pkat under optimal reaction conditions declining to v limit of 260 pkat in the presence of excess substrate APS. This sensitivity towards changes in substrate concentrations was parallelled by a high affinity and specificity: apparent K m APS: 2 · 10-6 mol · l-1, and K m ATP: 7 · 10-6 mol · l-1. The enzyme was found specific for ATP, d-ATP and CTP, while UTP, ITP and GTP showed marginal activity. The Hill coefficients suggested 4 binding sites for APS and 1 for ATP. Excessive APS resulted in a negative slope indicating 3 inhibiting sites of the substrate.Abbreviations APS Adenosine 5-phosphosulphate - dATP 2-deoxyadenosine 5-triphosphate - p-CMB p-chloromercuribenzoate - DTE dithioerythritol - DTT dithiothreitol - -MSH -mercaptoethanol - PAPS 3-phosphoadenosine 5-phosphosulphate - PAP 3-phosphoadenosine 5-phosphate - SDS sodium dodecyl sulphate This work is part of a dissertation submitted by H. G. J., Bochum 1982  相似文献   

14.
B. J. Miflin 《Planta》1972,105(3):225-233
Summary The reduction of nitrite by leaf discs has been studied. In short term experiments the reduction is markedly stimulated by light, but is not affected by the absence of oxygen or carbon dioxide from the gas phase. Carbon dioxide assimilation is more sensitive than nitrite reduction to 3-(3,4-dichloro-)-1,1-dimethyl urea (DCMU) inhibition. Uncouplers such as carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) do not inhibit nitrite reduction although dinitrophenol (DNP) has a small effect.Although nitrite stimulates oxygen evolution in the light in the absence of CO2 the stoichiometry of nitrite reduction to oxygen evolution is much less than would be predicted if nitrite is simply acting as a classical Hill reagent.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethyl urea - DNP 2,4-dinitrophenol - CCCP carbonyl cyanide m-chlorophenylhydrazone  相似文献   

15.
Summary Olfactory receptor neurons enzymatically dissociated from channel catfish olfactory epithelium were depolarized transiently following dialysis of IP3 or cAMP (added to the patch pipette) into the cytoplasm. Voltage and current responses to IP3 were blocked by ruthenium red, a blocker of an IP3-gated Ca2+-release channel in sarcoplasmic reticulum. In contrast, the responses to cAMP were not blocked by extracellularly applied ruthenium red, nor by l-cis-diltiazem or amiloride and two of its derivatives. The current elicited by cytoplasmic IP3 in neurons under voltage clamp displayed a voltage dependence different from that of the cAMP response which showed marked outward rectification. A sustained depolarization was caused by increased cytoplasmic IP3 or cAMP when the buffering capacity for Ca2+ of the pipette solution was increased, when extracellular Ca2+ was removed or after addition of 20–200 nm charibdotoxin to the bathing solution, indicating that the repolarization was caused by an increase in [Ca i ] that opened Ca2+-activated K+ channels. The results suggest that different conductances modulated by either IP3 or cAMP are involved in mediating olfactory transduction in catfish olfactory receptor neurons and that Ca2+-activated K+ channels contribute to the termination of the IP3 and cAMP responses.Abbreviations ATP adenosine 5-triphosphate - BAPTA (bis-(o-aminophenoxy)-ethane-N-N-N-N)-tetraacetic acid - cAMP adenosine cyclic 3,5-monophosphate - cGMP guanosine cyclic 3,5-monophosphate - CTX charybdotoxin - DCB 3,4-dichlorobenzamil - EDTA ethylenediaminetetraacetic acid - EGTA ethylenglycol-bis-(b-aminoethyl)-N-N-N-N-tetraacetic acid - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - IP3 inositol-1,4,5-triphosphate - NMDG N-methyl-d-glucamine We would like to thank the Tanabe Seiyaku Co., Ltd., for their gift of l-cis-diltiazem. This work was supported by National Institutes of Health grants DC00566 and BRSG S07RR05825.  相似文献   

16.
Our current work on a vacuolar membrane proton ATPase in the yeastSaccharomyces cerevisiae has revealed that it is a third type of H+-translocating ATPase in the organism. A three-subunit ATPase, which has been purified to near homogeneity from vacuolar membrane vesicles, shares with the native, membrane-bound enzyme common enzymological properties of substrate specificities and inhibitor sensitivities and are clearly distinct from two established types of proton ATPase, the mitochondrial F0F1-type ATP synthase and the plasma membrane E1E2-type H+-ATPase. The vacuolar membrane H+-ATPase is composed of three major subunits, subunita (M r =67 kDa),b (57kDa), andc (20 kDa). Subunita is the catalytic site and subunitc functions as a channel for proton translocation in the enzyme complex. The function of subunitb has not yet been identified. The functional molecular masses of the H+-ATPase under two kinetic conditions have been determined to be 0.9–1.1×105 daltons for single-cycle hydrolysis of ATP and 4.1–5.3×105 daltons for multicycle hydrolysis of ATP, respectively.N,N-Dicyclohexylcarbodiimide does not inhibit the former reaction but strongly inhibits the latter reaction. The kinetics of single-cycle hydrolysis of ATP indicates the formation of an enzyme-ATP complex and subsequent hydrolysis of the bound ATP to ADP and Pi at a 7-chloro-4-nitrobenzo-2-oxa-1,3-diazolesensitive catalytic site. Cloning of structural genes for the three subunits of the H+-ATPase (VMA1, VMA2, andVMA3) and their nucleotide sequence determination have been accomplished, which provide greater advantages for molecular biological studies on the structure-function relationship and biogenesis of the enzyme complex. Bioenergetic aspects of the vacuole as a main, acidic compartment ensuring ionic homeostasis in the cytosol have been described.Abbreviations CCCP carbonyl cyanidem-chlorophenyl hydrazone - DCCD N,N-dicyclohexylcarbondiimide - DES diethylstilbestrol - DIDS 4,4-diisothiocyano-2,2-stilbene disulfonic acid - NBD-Cl 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole - Pi inorganic phosphate - SDS sodium dodecylsulfate - SF6847 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile - SITS 4-acetamide-4-isothiocyanatostilbene-2,2-disulfonic acid - ZW3-14 N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate  相似文献   

17.
Summary Polymerization of various nucleoside-5-phosphorimidazolides has been conducted in neutral aqueous solution using divalent metal ions as catalysts. Oligonucleotide formation took place from each of the ribonucleoside-5-phosphorimidazolides, ImpC, ImpU, ImpA, ImpG, and ImpI. The yields and distributions of the resulting oligonucleotides varied depending on the difference of the nucleic acid base and the metal ions used. The catalytic effect of divalent metal ions on the formation of oligocytidylates occurred in the following order: Pb2+>Zn2+>Co2+, Mn2+>Cd2+>Cu2+>Ni2+>Ca2+, Mg2+, none >Hg2+. The order changes slightly for other types of oligoribonucleotide formation. Oligoribonucleotides up to hexamers were obtained in 35–55% overall yield, when Pb2+ ion was used as a catalyst. Zn2+ ions yielded oligoribonucleotides up to tetramers in 10–20% overall yield. The resulting oligonucleotides contained mainly 2–5 internucleotide linkages.Little or no oligonucleotide was obtained from nucleoside-5-phosphorimidazolides modified in the sugars, Imp(3-dA), Imp(2-dA), Imp(Ara), Imp(Aris), and Imp(Nep). The results indicate that a ribosyl system is required for the metal ion-catalyzed synthesis of oligonucleotides. Abbreviations. EDTA, ethylenediaminetetraacetic acid; Versenol,N-hydroxyethylethylenediaminetriacetic acid; Tris, tris-(hydroxymethyl)aminomethane; pN (N is A, C, G, U, I, 3-dA, 2-dA, AraA, Aris, or Nep), nucleoside-5-phosphate; Np, nucleoside-2(3)-phosphate; I, inosine; 3-dA, 3-deoxyadenosine; 2-dA, 2-deoxyadenosine; AraA, arabinosyladenine; Aris, aristeromycin; Nep, neplanocin A; ImpN, nucleoside-5-phosphorimidazolide; NppN, P1,P2-dinucleoside-5,5-pyrophosphate; (pN)n (n=2, 3, ...), oligomers of pN, numbers given between a nucleoside and a phosphate indicate the type of internucleotide linkage, e.g., pC2 p5C is 5-phosphorylcytidyl-(2–5)-cytidine; , cyclic dimers of pN; BAP, bacterial alkaline phosphatase; N.Pl, nuclease Pl; VPDase, venom phosphodiesterase; HPLC, high pressure liquid chromatography  相似文献   

18.
Washed everted vesicles of the methanogenic bacterium strain Gö1 catalyzed an H2-dependent reduction of the heterodisulfide of HS-CoM (2-mercaptoethanesulfonate) and HS-HTP (7-mercaptoheptanoylthreonine phosphate) (CoM-S-S-HTP). This process was independent of coenzyme F420 and was coupled to proton translocation across the cytoplasmic membrane into the lumen of the everted vesicles. The maximal H+/CoM-S-S-HTP ratio was 2. The tranmembrane electrochemical gradient thereby generated was shown to induce ATP synthesis from ADP+Pi, exhibiting a stoichiometry of 1 ATP synthesized per 2 CoM-S-S-HTP reduced (H+/ATP=4). ATP formation was inhibited by the uncoupler 3,5-di-tert-butyl-4-hydroxy-benzylidene-malononitrile (SF 6847) and by the ATP synthase inhibitor N,N-dicyclohexylcarbodiimide (DCCD). This energy-conserving system showed a stringent coupling. The addition of HS-CoM and HS-HTP at 1 mM each decreased the heterodisulfide reductase activity to 50% of the control. Membranes from Methanolobus tindarius showed F420H2-dependent but no H2-dependent heterodisulfide oxidoreductase activity. Neither of these activities was detectable in membranes of Methanococcus thermolithotrophicus.Abbreviations H+ transmembrane electrochemical gradient of H+ - CoM-SH 2-mercaptoethanesulfonate - F420 (N-l-lactyl--l-glutamyl)-l-glutamic acid phosphodiester of 7,8-didemethyl-8-hydroxy-5-deazariboflavin-5-phosphate - F420H2 reduced F420 - HTP-SH 7-mercaptoheptanoylthreonine phosphate - DCCD N,N-dicyclohexylcarbodiimide - SF 6847 3,5-di-ert-butyl-4-hydroxybenzylidenemalononitrile - Mb. Methanobacterium - Ml. Methanolobus - Mc. Methanococcus - MV methylviologen - BV benzylviologen - MTZ metronidazole  相似文献   

19.
The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp adenosine 5-triphosphate 3-diphosphate - ppApp adenosine 5-diphosphate 3-diphosphate - pApp adenosine 5-monophosphate 3-diphosphate - pppGpp guanosine 5-triphosphate 3-diphosphate  相似文献   

20.
The degradation of the phenylcoumaran substructure model compound methyl dehydrodiconiferyl alcohol by the white-rot wood decay fungus Phanerochaete chrysosporium was investigated using culture conditions optimized for lignin oxidation. Initial attack was in the cinnamyl alcohol side chain, which was oxidized to a glycerol structure. This was subsequently converted by loss of the two terminal carbon atoms, C and C, to yield a C-aldehyde structure, which was further oxidized to the C-acid compound. The next detected intermediate, a phenylcoumarone, was produced by double bond formation between C and C, and oxidation of the C-alcohol to an aldehyde group. Further oxidation of C to an acid yielded the next intermediate. The final identified degradation product was veratric acid. No products from the 5-substituted aromatic ring, and no phenolic products, were found. The initial glycerol-containing intermediate was a mixture of the threo and erythro forms, and no optical activity could be found, suggesting that its formation might have involved nonstereospecific C-C epoxidation followed by non-enzymatic hydrolysis of the epoxide.Abbreviations TLC thin layer chromatography - LDA lithium diisopropyl amide - DDQ 2,3-dichloro-5,6-dicyanobenzoquinone - MS mass spectrometry - UV ultraviolet spectroscopy  相似文献   

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