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E Starzyńska

Publications and source records attributed to E Starzyńska.

10 recordsLinked to original sources
PubMed1998

Adenosine 5'-tetraphosphate phosphohydrolase activity is an inherent property of soluble exopolyphosphatase from yeast Saccharomyces cerevisiae.

Homogeneous soluble exopolyphosphatase (EC 3.6.1.11) from yeast Saccharomyces cerevisiae, (scPPX1) behaves as an adenosine 5'-tetraphosphate phosphohydrolase (EC 3.6.1.14). The hydrolysis of adenosine 5'-tetraphosphate (p4A) to ATP and orthophosphate absolutely depends on one of the following cations: Co2+>Mn2+>Mg2+>Ni2+. Optimum pH is around 4.75 and the Km for p4A estimated at that pH in 50 mM sodium acetate and at 5 mM CoCl2 is 80+/-10 microM. Adenosine 5'-pentaphosphate (p5A) is degraded under these conditions 18-fold more slowly than p4A. Assuming that the mass of scPPX1 is 45 kDa, the calculated kcat values for p4A and for p5A are 723 and 40 s-1, respectively. Two other nucleoside 5'-tetraphosphates (p4N), guanosine tetraphosphate (p4G) and inosine tetraphosphate (p4I), were hydrolyzed to Pi and either GTP or ITP, respectively, at the same rate as that observed for the hydrolysis of p4A. Ammonium molybdate, sodium o-vanadate and zinc chloride inhibit the hydrolysis of p4A (I50 values are 0.08, 0.3 and 0.4 mM, respectively). This newly recognized 'acidic' adenosine tetraphosphatase activity from yeast is compared with two 'pH 8' adenosine tetraphosphatases described earlier in rabbit and yellow lupin.

Acid Anhydride Hydrolases↗
PubMed1997

Adenosine 5'-tetraphosphate phosphohydrolase from yellow lupin seeds: purification to homogeneity and some properties.

Adenosine 5'-tetraphosphate phosphohydrolase (EC 3.6.1.14) has been purified to homogeneity from the meal of yellow lupin (Lupinus luteus) seeds. The enzyme is a single polypeptide chain of 25+/-1 kDa. It catalyses the hydrolysis of a nucleoside 5'-tetraphosphate to a nucleoside triphosphate and orthophosphate, and hydrolysis of tripolyphosphate but neither pyrophosphate nor tetraphosphate. A divalent cation, Mg2+, Co2+, Ni2+ or Mn2+, is required for these reactions. The pH optimum for hydrolysis of adenosine 5'-tetraphosphate (p4A) is 8.2, Vmax is 21+/-1.7 micromol/min per mg of protein and the Km for p4A is 3+/-0.6 microM. At saturating p4A concentrations, the rate constant for the reaction is 8.5+/-0.7 s-1 [at 30 degrees C, in 50 mM Hepes/KOH (pH8.2)/5 mM MgCl2/0.1 mM dithiothreitol]. p4A and guanosine 5'-tetraphosphate are hydrolysed at the same rate. Adenosine 5'-pentaphosphate (p5A) is degraded 1/200 as fast and is converted into ATP and two molecules of orthophosphate, which are liberated sequentially. This contrasts with the cleavage of p5A by the lupin diadenosine tetraphosphate hydrolase (EC 3.6.1.17), which gives ATP and pyrophosphate. Zn2+, F- and Ca2+ ions inhibit the hydrolysis of p4A with I50 values of 0.1, 0.12 and 0.2 mM respectively.

Acid Anhydride Hydrolases↗
PubMed1996

Dinucleoside 5', 5"'-P1, P3-triphosphate hydrolase from yellow lupin (Lupinus luteus) seeds: purification to homogeneity and hydrolysis of mRNA 5'-cap analogs.

Three separable forms of diadenosine 5',5"'-P1, P3-triphosphate (Ap3A)-degrading activity were revealed when proteins obtained from the meal of yellow lupin seeds by ammonium sulfate precipitation were chromatographed on a DEAE-Sephacel column. The major form, which eluted first at the lowest salt concentration (0.15 M KCl), was free of any activity converting the reaction products, ADP and AMP. Its further purification by gel filtration on Sephadex G-200 and by affinity elution from an AMP-agarose column yielded homogeneous protein as demonstrated on SDS-polyacrylamide gel electrophorograms. The enzyme is a single polypeptide chain of M(r) 41 kDa. Eleven guanosine-containing dinucleoside triphosphates, including analogs of the mRNA 5'-cap structure, have been tested as potential substrates of the lupin "Ap3A hydrolase." All have been hydrolyzed yielding mixtures of corresponding nucleoside mono- and diphosphates. Asymmetrical compounds gave four products; m7Gp3G, et7Gp3G, and bz7Gp3G were hydrolyzed randomly, whereas m7Gp3A, m7Gp3C, and m7Gp3U yielded at least 80% m7GMP plus corresponding NDP and 20% or less NMP plus m7GDP. Hydrolysis of the guanosine-containing hybrids, Ap3G, Cp3G, and Up3G, yielded at least 85% GMP plus corresponding NDP. All dinucleotides containing the m7G-moiety were hydrolyzed 2- to 4.5-fold faster than Ap3A. Thus a general name, "dinucleoside triphosphate hydrolase," is more appropriate for the enzymatic activity described.

Acid Anhydride Hydrolases↗
PubMed1995

Conversion of adenosine(5') oligophospho(5') adenosines into inosine(5') oligophospho(5') inosines by non-specific adenylate deaminase from the snail Helix pomatia.

Until now, the catabolism of adenosine(5')triphospho(5')adenosine (Ap3A) and adenosine(5')tetraphospho(5')adenosine (Ap4A) has been thought to commence with either hydrolytic or phosphorolytic cleavage of their oligophosphate chains, depending on the organism. Here, we show that in the extracts from the retractile 'foot' of the snail Helix pomatia deamination predominates; the adenosine moieties of these and other adenosine(5')oligophospho(5')adenosines (ApnAs) undergo successive deamination leading, via an inosine(5')oligophospho(5')adenosine (IpnA), to the corresponding inosine(5')oligophospho(5')inosine (IpnI). The reactions are catalyzed by the non-specific adenylate deaminase described earlier (Stankiewicz, A.J. (1983) Biochem. J. 215, 39-44). We describe TLC and HPLC systems which allow the separation of any of the deaminated derivatives from its parent compound; Ap2A, Ap3A, Ap4A or Ap5A. The Km values for these substrates are 20, 22, 32 and 39 microM, respectively, whereas the Km for 5'-AMP is 12 microM. Relative substrate specificities for these compounds amount to 25, 18, 14, 7 and 100. The enzyme was shown also to deaminate phosphonate and thiophosphate analogues of Ap3A.

AMP Deaminase↗
PubMed1993

Human placental (Asymmetrical) diadenosine 5',5'''-P1,P4-tetraphosphate hydrolase: purification to homogeneity and some properties.

The diadenosine 5',5'''-P1,P4-tetraphosphate (asymmetrical) hydrolase (EC 3.6.1.17) from human placenta has been purified to homogeneity by ammonium sulfate fractionation, ion-exchange chromatography on DEAE-Sephacel, gel filtration on Sephadex G-100, and affinity elution from red Sepharose. The enzyme is a single polypeptide of M(r) 19,200. It exhibits maximum (100%) activity at pH 7.3 in the presence of 3 mM MgCl2 and 60, 50, and 40% of the activity in 1 mM CoCl2, 0.1 mM ZnCl2, and 0.5 mM MnCl2, respectively. The Km value calculated for diadenosine tetraphosphate in the presence of Mg2+ is 10 microM and in the presence of Zn2+ 40 microM. Adenosine 5'-tetraphosphate, guanosine 5'-tetraphosphate, and fluoride proved to be inhibitors of the diadenosine tetraphosphate hydrolase; the I50 values were 6, 10, and 20 microM, respectively. Diguanosine tetraphosphate, bis-2,6-diaminopurine beta-D-ribofuranoside tetraphosphate, and diadenosine pentaphosphate were substrates for the hydrolase; relative velocities of hydrolysis estimated for 0.5 mM diadenosine tetraphosphate and these other substrates were 1:0.51:0.44:0.20, respectively. Diadenosine tetraphosphate analogues with P2-P3 bridges such as -CF2-, -CCl2-, and -CH2- were hydrolyzed to adenosine 5'-phosphate and the corresponding adenosine 5'-triphosphate analogue.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Anhydride Hydrolases↗
PubMed1991

Purification of apyrase from yellow lupin cotyledons after extraction with perchloric acid.

Neutralized 1 M perchloric acid (PCA) extracts of yellow lupin (Lupinus luteus) seedling cotyledons contain considerable amounts of apyrase (EC 3.6.1.5). Investigators who use PCA extraction for the estimation of nucleotide levels, particularly in plant tissues, should be aware of this danger. Only when the material is treated with 1.8-2 M PCA are the extracts obtained free of apyrase activity. Chromatography of neutralized 1 M extracts obtained from 7-day-old seedling cotyledons on DEAE-Sephacel and Sephadex G-100 yields almost homogeneous apyrase that shows a band of M(r) 51,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. The molecular weight of the native enzyme is also about 51,000. The apyrase preparation is free of nonspecific phosphatases, nucleotidases, and adenosine nucleosidase, as well as dinucleoside polyphosphate-degrading enzymes. The apyrase exhibits a broad pH optimum between 6 and 8. Mg2+ and Ca2+ are required for maximum activity; Zn2+ and Mn2+ are less effective and Co2+, Ni2+, and Cd2+ are without effect. The Km values for ATP and ADP are about 20 microM. All common 5'-nucleoside tri- and diphosphates as well as adenosine 5'-tetraphosphate are substrates.

Adenine Nucleotides↗
PubMed1989

Studies on some specific Ap4A-degrading enzymes with the use of various methylene analogues of P1P4-bis-(5',5'''-adenosyl) tetraphosphate.

Six new methylenephosphonate analogues of P1P4-bis-(5',5'''-adenosyl) tetraphosphate, Ap4A, having P2-P3 carbon bridges CF2, CCl2 and CH2CH2 or P1-P2 and P3-P4 carbon bridges CF2, CCl2 and CH2CH2 in the tetraphosphate chain, were examined as substrates or inhibitors for two specific Ap4A-degrading enzymes: (asymmetrical) Ap4A hydrolase (EC 3.6.1.17) from yellow-lupin seeds and (symmetrical) Ap4A hydrolase (EC 3.6.1.41) from Escherichia coli. All analogues in which the central oxygen atom was replaced by a stable carbon bridge were hydrolysed by the asymmetrical hydrolase (CF2 greater than CCl2 greater than O greater than CHBr greater than CH2 greater than CH2CH2). As expected, these analogues were not hydrolysed by the symmetrical hydrolase, which was also unable to act on analogues having P1-P2 and P3-P4 carbon bridges.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

Hydrolysis of some mRNA 5'-cap analogs catalyzed by the human Fhit protein--and lupin ApppA hydrolases.

Hydrolysis of the following four cap analogs: m7G(5')ppp(5')A, m7G(5')ppp(5')m6A, m7G(5')ppp(5')m2'OG and m7G(5')ppp(5')2'dG catalyzed by homogeneous human Fhit protein and yellow lupin Ap3A hydrolase has been investigated. The hydrolysis products were identified by HPLC analysis and the K(m) and Vmax values calculated based on the data obtained by the fluorimetric method.

Acid Anhydride Hydrolases↗