| | 2 | Author
| Satham Saphon, Peter Gräber | Requires cookie* | | | Title
| External Proton Uptake, Internal Proton Release and Internal pH Changes in Chromatophores from Rps. sphaeroides Following Single Turnover Flashes  | | | | Abstract
| The change in internal pH in chromatophores from R ps. sph aeroides following short flash ex citation has been investigated using the method of the fluorescence quenching of 9-aminoacridine. (1) A single turnover flash induced a fluorescence quenching of ^ 0.4%. The fluorescence quenching was stim ulated by valinomycin, and oligomycin, and inhibited by antim ycin A. (2) The extent of the pH gradient generated by a single turnover flash at the external pH ^ 8 was estim ated to be less than 0.4 unit. (3) In a multiflash experiment the change in internal pH induced by each flash was found to be not linearly dependent on the num ber of protons which had been taken up after each flash from the external medium. We discuss the significance of the results w ith respect to the mechanism of phosphorylation. The release of H+ taken up outside the chromatophore into the m em brane could not be excluded by the present results. | | | |
Reference
| Z. Naturforsch. 33c, 715—722 (1978); received July 31 1978 | | | |
Published
| 1978 | | | |
Keywords
| Proton Translocation, Internal pH-Changes, Phosphorylation | | | |
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| default:Reihe_C/33/ZNC-1978-33c-0715.pdf | | | | Identifier
| ZNC-1978-33c-0715 | | | | Volume
| 33 | |
| 3 | Author
| Hans-Adolf Arfmann, Hassan Baydoun | Requires cookie* | | | Title
| Preferential Phosphorylation of High Mobility Group Protein 17 in vitro by a Nuclear Protein Kinase | | | | Abstract
| The ability of the high mobility group proteins (H M G -1,2,14 and 17) to serve as substrate for protein kinases was investigated by incubating them with a cytoplasmic and nuclear kinase. In both cases phosphate was incorporated into all four HMG proteins. The amount of phosphate incorporated and the specificity for the four proteins was quite different for the two kinases. Whereas the cytoplasmic kinase phosphorylated the HMG-1 and 2 to a higher degree than HM G -14 and 17, the nuclear kinase exhibited a high specificity for the H M G -17, leaving the other three proteins with only a small amount. The high preference o f a nuclear kinase for HM G-17 may be indicative o f a specific phosphorylation occuring also in vivo. | | | |
Reference
| Z. Naturforsch. 36c, 319—322 (1981); received October 6/November 26 1980 | | | |
Published
| 1981 | | | |
Keywords
| High Mobility Group Proteins, Phosphorylation, Nuclear and Cytoplasmic Kinase | | | |
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| default:Reihe_C/36/ZNC-1981-36c-0319.pdf | | | | Identifier
| ZNC-1981-36c-0319 | | | | Volume
| 36 | |
| 6 | Author
| | Requires cookie* | | | Title
| Phosphorylation of Coformycin and 2 -Deoxycoformycin, and Substrate and Inhibitor Properties of the Nucleosides and Nucleotides in Several Enzyme Systems | | | | Abstract
| Under conditions where 2'-deoxycoformycin is enzymatically phosphorylated by wheat shoot phosphotransferase to the 5'-phosphate in 15—20% yield, coformycin is a relatively poor sub strate, and is phosphorylated only to the extent of < 5%. However, chemical phosphorylation of coformycin by modifications of the Yoshikawa procedure led to isolation of coformycin-5'-phos phate in 20% overall yield. Coformycin-5'-phosphate was characterized by various criteria, including 'H NMR spectro scopy. Comparison of the spectrum with that of the parent nucleoside indicated that the nu cleotide is predominantly, although not exclusively, in the conformation anti about the glycosidic bond. Like 2'-deoxycoformycin-5'-phosphate, coformycin-5'-phosphate was a feeble substrate of snake venom 5'-nucleotidase, and is hydrolyzed, quantitatively, at only 2% the rate for 5'-AMP. With 5'-AMP analogues as substrate, the 5'-phosphates of both coformycin and deoxycoformycin were poor inhibitors of the enzyme, with K, values > 0.3 mM. The 5'-phosphates of both coformycin and deoxycoformycin do not significantly inhibit adenosine deaminase (K} > 0.2 m M), but are potent inhibitors of adenylate deaminase (Kj < 10"9 m). Neither coformycin nor deoxycoformycin are inhibitors of mammalian purine nucleoside phosphorylase. The stabilities of coformycin, deoxycoformycin, and their 5'-phosphates, have been examined as a function of pH, and nature of the buffer medium. In particular, all exhibit instability in acid and neutral media, but are relatively stable in the vicinity of pH 9. Some biological aspects of the overall results are presented. | | | |
Reference
| Z. Naturforsch. 40c, 710—714 (1985); received March 5/June 3 1985 | | | |
Published
| 1985 | | | |
Keywords
| Coformycin, 2'-Deoxycoformycin, Phosphorylation, 5'-Phosphates, Substrates, Inhibitors | | | |
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| default:Reihe_C/40/ZNC-1985-40c-0710.pdf | | | | Identifier
| ZNC-1985-40c-0710 | | | | Volume
| 40 | |
| 7 | Author
| Bernhard Huchzermeyer | Requires cookie* | | | Title
| Phosphate Binding to Isolated Chloroplast Coupling Factor (CF^ | | | | Abstract
| A single binding site for phosphate was found on isolated chloroplast coupling factor in the absence of nucleotides. In our experiments the phosphate binding site showed a K d of 170 JIM. We did not observe any differences whether the ATPase activity of CF] had been activated or not. If the enzyme was incubated with [y-32 P]ATP the amount of 32 P bound per CF, depended on the pretreatment of the enzyme: In the presence of ADP no ATP or phosphate was bound to CF,. After activation of ATPase activity one mol of ATP per mol CF, was rapidly bound and hydro-lyzed while there was a slowly occurring binding of another phosphate without concomitant nucleotide binding. We conclude that there are two different types of phosphate binding observed in our experi-ments: 1) Inorganic phosphate can be bound by one catalytic site per mol of CTv 2) The y-phosphate of ATP is able to bind to an ATP binding domain of the enzyme if this domain can exchange substrates with the incubation medium. This ATP binding domain appears to differ from the site binding inorganic phosphate, because at least a portion of the coupling factor contains more than one labelled phosphate during our ATPase tests. | | | |
Reference
| Z. Naturforsch. 43c, 213—218 (1988); received July 27/November 19 1987 | | | |
Published
| 1988 | | | |
Keywords
| Chloroplast, Coupling Factor, Binding Sites, ATPase, Phosphorylation | | | |
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| default:Reihe_C/43/ZNC-1988-43c-0213.pdf | | | | Identifier
| ZNC-1988-43c-0213 | | | | Volume
| 43 | |
| 8 | Author
| Elisabeth Fassold, Wilhelm Hasselbach, Bernd Küchler | Requires cookie* | | | Title
| Effect of Non-Solubilizing SDS Concentrations on High Affinity Ca2+ Binding and Steady State Phosphorylation by Inorganic Phosphate of the Sarcoplasmic Reticulum ATPase | | | | Abstract
| In this investigation low, non-solubilizing concentrations of the strong anionic detergent SDS were used to perturbate the interaction of Ca2+ and P, with their respective binding domains on the sarcoplasmic reticulum Ca-transport ATPase. Rising SDS concentrations produce a two-step decline of Ca2+-dependent ATP hydrolysis. At pH 6.15, SDS differently affects high affinity Ca2+ binding and phosphorylation by inorganic phosphate and releases the "mutual exclusion" of these two ligand binding steps. The degree of uncoupling is considerably more pronounced in the presence of 20% Me2SO. The reduction of Ca2+ binding by SDS is demonstrated to be a result of decreased affinity of one of the two specific high affinity binding sites and of perturbation of their cooperative inter action. Higher SDS partially restores the original high Ca2f affinity but not the cooperativity of binding. Phosphorylation exhibits a higher SDS sensitivity than Ca2+ binding: Increasing SDS competitively inhibits and then completely abolishes phosphoenzyme formation. Thus. SDS binds to the phosphorylation domain, evidently involving the Lys352 residue of the ATPase molecule; this is accompanied by a more unspecific concentration-dependent SDS effect, probably mediated by hydrophobic force, which, finally, suppresses phosphorylation. Me2SO does neither qualitatively affect the SDS-dependent chemical properties of the vesicular material nor the SDS-dependent perturbation of the investigated reaction steps. | | | |
Reference
| Z. Naturforsch. 44c, 139 (1989); received November 28 1988 | | | |
Published
| 1989 | | | |
Keywords
| Sarcoplasmic Reticulum ATPase, Calcium Binding, Phosphorylation, SDS | | | |
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| default:Reihe_C/44/ZNC-1989-44c-0139.pdf | | | | Identifier
| ZNC-1989-44c-0139 | | | | Volume
| 44 | |
| 9 | Author
| M. Aria, TeresaG. Iardi | Requires cookie* | | | Title
| Significance of Photosystem II Core Phosphorylation Heterogeneity for the Herbicide-Binding Domain | | | | Abstract
| In recent papers the heterogeneous nature o f photosystem (PS) II core phosphorylation has been revealed (Giardi et al., B B R C 176, 1 2 9 8 -1 3 0 5 (1991); Plant Physiol. 100, 1 9 4 8 -1 9 5 4 (1992)). In this paper the action o f endogenous and exogenous phosphatases both on the dis tribution of phosphorylated PS II core populations and on herbicide-binding activity in pho tosystem II preparations from Spinacia oleracea L. has been investigated. The results indicate that these phosphatases modify the photosystem II core phosphorylation heterogeneity at a different level. Dark incubation causes a partial dephosphorylation of D, and D 2 proteins by endogenous phosphatase(s) and changes the relative distribution o f phosphorylated photosys tem II core populations, while the action o f the alkaline phosphatase leads to extensive de-phosphorylation and to the detachment of PsbH protein from the photosystem II core. De phosphorylation by the two alternative methods results in a differential modification of herbi cide-binding activity. It is suggested that photosystem II heterogeneity with respect to the herbicide action, observed in vivo, could be a consequence o f PS II core phosphorylation heterogeneity. | | | |
Reference
| Z. Naturforsch. 48c, 241—2 (1993); received Novem ber 9 1992 | | | |
Published
| 1993 | | | |
Keywords
| Photosystem II Core, Phosphorylation, Heterogeneity, Phosphatase, Herbicide-Binding Dom ain | | | |
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| default:Reihe_C/48/ZNC-1993-48c-0241.pdf | | | | Identifier
| ZNC-1993-48c-0241 | | | | Volume
| 48 | |
| 10 | Author
| Ryszard Stolarski3, Zygmunt Kazimierczuk3, Piotr Lassotab, David Shugara- | Requires cookie* | | | Title
| Acyclo Nucleosides and Nucleotides: Synthesis, Conformation and Other Properties, and Behaviour in Some Enzyme Systems, of 2',3'-Seco Purine Nucleosides, Nucleotides and 3 ':5'-Cyclic Phosphates, Analogues of cAMP and cGMP | | | | Abstract
| The 3':5'-cyclic phosphates of 2',3'-secoadenosine and guanosine, structural analogues of cAMP and cGMP, were synthesized by cyclization of the 5'-phosphates of 2',3'-secoadenosine and guanosine, respectively. The 2',3'-seco-3':5'-cAMP was converted to the IM P analogue by nitrous acid deamination, and to the 8-bromo analogue by bromination. Chemical phosphorylation of 2',3'-secoadenosine gave four products, the major one of which, in 50% yield, was 2',3'-seco-3':5'-cAMP, identical to that obtained by the cyclization reaction above. The three other products have been tentatively identified. The conformations in solution of the seco nucleosides, their 5'-monophosphates, and their 3':5'-cyclic phosphates, were determined with the aid of 'H , 13C and 31P N M R spectroscopy, particular attention being devoted to orientations about the C —O bonds and the glycosidic bond, and the results compared with crystallographic data available for the 2',3'-seco congener of ribofuranosyl benzimidazole. The findings are briefly discussed in relation to substrate and inhibitor properties in some enzyme systems. Some of the foregoing compounds have been examined as potential enzyme substrates and inhibitors. In particular, the seco 3':5'-cyclic phosphates are resistant to cAM P cyclic phos phodiesterase of mammalian origin, but are slowly hydrolyzed by purified higher plant cyclic nucleotide phosphodiesterase to the corresponding monophosphates. | | | |
Reference
| Z. Naturforsch. 41c, 758—770 (1986); received March 17 1986 | | | |
Published
| 1986 | | | |
Keywords
| 2', 3'-Seco Cyclic Nucleotides, cAMP and cGMP Analogues, Synthesis, Phosphorylation, N M R and Conformation, Enzymology | | | |
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| default:Reihe_C/41/ZNC-1986-41c-0758.pdf | | | | Identifier
| ZNC-1986-41c-0758 | | | | Volume
| 41 | |
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