6-phosphogluconate dehydrogenase
6-phosphogluconate dehydrogenase is the third enzyme of the Pentose Phosphate pathway. It catalyses the oxidative decarboxylation of 6-phosphogluconate using NADP+. The product of this reaction is ribulose 5-P, CO2 and NADPH. This is the second step of the pentose phosphate pathway producing NADPH and the last step of the oxidative phase.
Contents
Chemical reaction
Rate equation
The basic reaction mechanism can be modelled with an ordered Bi-ter equation [1]
![v=\frac{V_{max}*[NADP^+]*[6-PGA]}{k_{iNADP}*k_{6-PGA}+k_{6-PGA}*[NADP^+]+k_{NADP^+}*[6-PGA]+[NADP^+]*[6-PGA]}](/wiki/images/math/1/8/4/184c3b0a56198ff4c7985bd0ec0d9816.png)
Parameters values
| Name | Value | Units | Organism | Remarks |
| Km 6-PGA | 0.0292[1] | mM | Pig liver | |
| 0.051±0.021[2] | mM | Recombinant human protein | ||
| 0.063±0.004[2] | mM | Recombinant human protein | ||
| 0.06±0.005[2] | mM | Recombinant human protein | ||
| 0.016±0.0008[2] | mM | Human liver | ||
| 0.023±0.0001[2] | mM | Human erythrocyte | ||
| 0.041[2] | mM | Human Brain | ||
| Km NADP | 0.0135[1] | mM | Pig liver | |
| 0.018±0.0008[2] | mM | Recombinant human protein | ||
| 0.025 ± 0.001[2] | mM | Recombinant human protein | ||
| 0.022 ± 0.0004[2] | mM | Recombinant human protein | ||
| 0.0037[2] | mM | Human Brain | ||
| Vmax | 0.00493*10-3[1] | mM/min | Pig liver | |
| Kcat | 73 ± 19[2] | Recombinant human protein | ||
| 57 ± 2[2] | Recombinant human protein | |||
| 44 ± 4[2] | Recombinant human protein | |||
| 21 ± 0.07[2] | Human liver | |||
| 21.3 ± 0.01[2] | Human erythrocyte | |||
| Ki NADP | 0.0048 ± 0.0008[1] | mM | Pig liver | |
Parameters with uncertainity
To cover the uncertainity inside cancer cells, the Km for 6PGA ad NADP were calculated using in vivo and in vitro measures. This information has been taken from Barden et al, 2013[2]. Th average Kcat was calculated in the same way, taking in account in vivo and in vitro values.
| Name | Value | Units | Organism | Remarks |
| Km 6PGA | 0.042 ± 0.019 | mM | Human | |
| Km NADP | 0.017 ± 0.0094 | mM | Human | |
| Kcat | 48.75 ± 21.98 | s-1 | Human | |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Toews, Myron L., M. I. Kanji, and W. R. Carper. "6-Phosphogluconate dehydrogenase. Purification and kinetics." Journal of Biological Chemistry 251.22 (1976): 7127-7131. ([1])
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 Barden Chan, Vikas P. Sukhatme, One-step purification of soluble recombinant human 6-phosphogluconate dehydrogenase from Escherichia coli, Protein Expression and Purification, Volume 92, Issue 1, November 2013, Pages 62-66, ISSN 1046-5928 ([2])
