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Spectral and kinetic studies of phosphate and magnesium ion binding to yeast inorganic pyrophosphatase
| Content Provider | Scilit |
|---|---|
| Author | Smirnova, Iruna N. Shestakov, Alexander S. Dubnova, Elena B. Baykov, Alexander A. |
| Copyright Year | 1989 |
| Description | Journal: Journal of Biological Inorganic Chemistry Inorganic pyrophosphatase must bind two phosphate molecules in order to catalyze pyrophosphate synthesis. In this report it is shown that $P_{i}$ causes marked effect on the absorption spectrum of baker's yeast inorganic pyrophosphatase and this effect can be used to analyze $P_{i}$ binding to this enzyme. A series of absorbance versus $P_{i}$ concentration curves in the presence of 0.5–20mM free $Mg^{2+}$ were obtained at pH 7.2 and computer-fitted to 19 models. The dissociation constant of magnesium phosphate (8.5 ± 0.4 mM) used in this analysis was measured with a $Mg^{2+}$ -sensitive electrode. The best model implies successive binding of two magnesium phosphate molecules or random-order binding of magnesium phosphate and free phosphate molecules. The first route predominates at physiological concentrations of $Mg^{2+}$. The $P_{i}$-inhibition pattern of pyrophosphate hydolysis confirmed that $P_{i}$ adds to the active site and provided further evidence for the existence of an activating $P_{i}$-binding site. The possibility is raised that the pathways of pyrophosphate synthesis and hydrolysis by inorganic pyrophosphatase may differ in the sense that the binding of the fourth metal ion/subunit may facilitate the synthesis and inhibit the hydrolysis. |
| Related Links | http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1989.tb14852.x/pdf |
| Ending Page | 456 |
| Page Count | 6 |
| Starting Page | 451 |
| ISSN | 09498257 |
| e-ISSN | 14321327 |
| DOI | 10.1111/j.1432-1033.1989.tb14852.x |
| Journal | Journal of Biological Inorganic Chemistry |
| Issue Number | 2 |
| Volume Number | 182 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 1989-06-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: Journal of Biological Inorganic Chemistry Biochemistry and Molecular Biology Inorganic Pyrophosphatase Pyrophosphate Synthesis Magnesium Phosphate |
| Content Type | Text |
| Resource Type | Article |
| Subject | Biochemistry Inorganic Chemistry |
