Difference between revisions of "UDPG-pyrophosphorylase"

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==References==
 
==References==
 
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Revision as of 11:58, 8 May 2014


This enzyme converts UTP and G1P to UDP-glucose (UDPG) and pyrophosphate (PPi)

Chemical equation

 UTP + Glc1P \rightarrow UDPG + PPi

Rate equation

Reversible Bi substrate Michaelis-Menten equation with random binding order is used [1]

 \frac{ \frac{V_{max}}{K_{UTP}K_{Glc1P}} \left( [UTP][Glc1P] - \frac{[UDPG][PPi]}{K_{eq}} \right)  }{ \left( 1 + \frac{[UTP]}{K_{UTP}} + \frac{[PPi]}{K_{PPi}} \right) \left( 1 + \frac{[UDPG]}{K_{UDPG}} + \frac{[Glc1P]}{K_{Glc1P}} \right)  }

Parameter values

Parameter Value Units Organism Remarks
V_{max} 200 [2] min^{-1} Recombinant, human muscle
K_{Glc1P} 0.4 [3] mM
K_{UTP} 0.92 [3] mM
K_{UDPG}  6.3 \times 10^{-2} [3] mM
K_{ppi} 0.38[3] mM
K_{eq} 0.24[3] Dimensionless


Parameters with uncertainty

  • The value of V_{max} is reported to be 9.6 % of V_{max, PGLM}. The Std. Dev. for V_{max, PGLM} was considered to be 10.5% of its mean value. Same error percentage is considered for V_{max}.
Parameter Value Units Organism Remarks
V_{max} 200 \pm 21 [2] min^{-1} Recombinant, human muscle
K_{Glc1P}  0.4 \pm 0.051 [3] mM
K_{UTP} 0.97 \pm 0.08 [3] mM
K_{UDPG}  0.063 \pm 0.006 [3] mM
K_{ppi} 0.38 \pm 0.036[3] mM
K_{eq} 0.24[3] Dimensionless

References

  1. Palm, D.C. (2013). The regulatory design of glycogen metabolism in mammalian skeletal muscle (Ph.D.). University of Stellenbosch
  2. 2.0 2.1 Villar-Palasi C & Larner J (1960). Levels of activity of the enzymes of the glycogen cycle in rat tissues. Arch Biochem Biophys 86, 270–273.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Duggleby RG, Chao YC, Huang JG, Peng HL & Chang HY (1996). Sequence differences between human muscle and liver cDNAs for UDPglucose pyrophosphorylase and kinetic properties of the recombinant enzymes expressed in Escherichia coli. Eur J Biochem 235, 173–179.