Transformation of AA to 12-HPETE

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LOX enzymes oxidise AA to generate hydroxy fatty acids. In the skin, the 12-LOX isoform of LOX is more active than others. This isoform is highly expressed in the resident cells of both compartments, epidermal keratinocytes and dermal fibroblasts (Dowd, Kobza Black et al. 1985). The 12- LOX enzyme catalyses the addition of O2 at the C-12 position of AA, producing 12-HPETE.

Reaction

R179AA - HPETE12.jpg

Chemical equation

AA \rightleftharpoons 12-HPETE

Rate equation

R19.PNG

Enzyme Parameters

Kms

Literature values
Value Units Species Notes Reference
7.20E-03 mM Human Expression Vector: Platelet

Enzyme: 12-Lipoxygenase pH: 7.4 Temperature: 37°C.

[1]
8.00E-02 mM Human Expression Vector: Platelet

Enzyme: 12-Lipoxygenase pH: 7 Temperature: 24

[2]
1.00E-02 mM Human Platlet Expression Vector: Baculovirus

Enzyme: 12-Lipoxygenase pH: 8 Temperature: 37

[3]
7.90E-03 ± 8.00E-04 mM Human Expression Vector: Platelets

Enzyme:12-Lipoxygenase pH: 7.4 Temperature: 37

[4]
Description of the 12-LOX Kms distribution
Mode (mM) Confidence Interval Location parameter (σ) Scale parameter (σ)
7.60E-03 4.34E+00 -4.48E+00 6.30E-01


Kmp

Description of the 12-LOX Kmp distribution
Mode (mM) Location parameter (µ) Scale parameter (σ)
7.30E-03 -4.52E+00 6.28E-01

kcat

Literature values
Value Units Species Notes Reference
336 ± 12 per minute Human Expression Vector: Human reticulocyte

Enzyme: 15-lipoxygenase-1 pH: 7.5 Temperature: 25

[5]
504 per minute Wild Boar Expression Vector: E. coli.

Enzyme: 12-Lipoxygenase pH: 7.4 Temperature: 37

[6]
Description of the 12-LOX kcat distribution
Mode (min-1) Confidence Interval Location parameter (µ) Scale parameter (σ)
4.87E+02 1.20E+00 6.22E+00 1.80E-01


Enzyme concentration

12-LOX Abundance
Value Units Species Notes Reference
19.8 ppm Human Expression Vector: Spleen

Enzyme: 12-LOX pH: 7.5 Temperature: 37 °C

[7]
1.60 ppm Human Expression Vector: Liver

Enzyme: 12-LOX pH: 7.5 Temperature: 37 °C

[8]
0.28 ppm Human Expression Vector: Gut

Enzyme: 12-LOX pH: 7.5 Temperature: 37 °C

[8]
0.11 ppm Human Expression Vector: Pancreas

Enzyme: 12-LOX pH: 7.5 Temperature: 37 °C

[8]
Description of the 12-LOX concentration distribution
Mode (mM) Confidence Interval Location parameter (µ) Scale parameter (σ)
4.98E-01 7.23E+00 7.12E-01 1.19E+00

Keq

Literature values
Gibbs Free Energy Change Units Species Notes Reference
(-69.979996) kcal/mol Not stated Estimated

Enzyme: 12-LOX Substrate: Arachidonate Product: 12-HPETE pH: 7.3 ionic strength: 0.25

[9]
Description of the 12-LOX Keq distribution
Mode Confidence Interval Location parameter (µ) Scale parameter (σ)
2.27E+51 1.00E+01 1.19E+02 8.90E-01

References

  1. ↑ Lagarde M. "Subcellular localization and some properties of lipoxygenase activity in human blood platelets. Biochem J. 1984 Sep 1;222(2):495-500.
  2. ↑ Hada T. "Catalytic properties of human platelet 12-lipoxygenase as compared with the enzymes of other origins. Biochim Biophys Acta. 1991 Apr 24;1083(1):89-93.
  3. ↑ Chen X. S. "Purification and characterization of recombinant histidine-tagged human platelet 12-lipoxygenase expressed in a baculovirus/insect cell system. Eur J Biochem. 1993 Jun 15;214(3):845-52.
  4. ↑ Romano M. "Lipoxin synthase activity of human platelet 12-lipoxygenase. Biochem J. 1993 Nov 15;296 ( Pt 1):127-33.
  5. ↑ [www.ncbi.nlm.nih.gov/pubmed/19469483 Wecksler A. "Mechanistic Investigations of Human Reticulocyte 15- and Platelet 12-Lipoxygenases with Arachidonic Acid Biochemistry, 2009, 48 (26), pp 6259–6267]
  6. ↑ Richards K. "Leukocyte 12-Lipoxygenase:  Expression, Purification, and Investigation of the Role of Methionine Residues in Turnover-Dependent Inactivation and 5,8,11,14-Eicosatetraynoic Acid Inhibition Biochemistry, 1997, 36 (22), pp 6692–6699
  7. ↑ M. Wilhelm Mass-spectrometry-based draft of the human proteome Nature, 2014 509, 582–587
  8. ↑ 8.0 8.1 8.2 M. Kim A draft map of the human proteome Nature, 2014 509, 575–581
  9. ↑ Caspi et al 2014, "The MetaCyc database of metabolic pathways and enzymes and the BioCyc collection of Pathway/Genome Databases," Nucleic Acids Research 42:D459-D471

Related Reactions

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