Transformation of PGH2 to PGD2

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PGD2 is synthesised from PGH2 via the prostaglandin D synthase (PGDS) enzyme. Upon binding to the D prostanoid (DP) receptor, the prostanoid stimulates keratinocyte cells to produce peptides which target invading pathogens (Homey, Steinhoff et al. 2006). However this species is primarily produced by LCs, mast cells and melanocytes in the cutaneous compartment (Ujihara, Horiguchi et al. 1988, Shimura, Satoh et al. 2010), and as a consequence it is unlikely to be observed in the early experimental procedures of this project.

Reaction

Chemical equation

$PGH2 \rightleftharpoons PGD2$

Rate equation

Enzyme Parameters

Michaelis-Menten Constants

Value	Units	Species	Notes	Reference
4.00E-03	$mM$	Human	Expression Vector: Human Cell Enzyme: PGDS pH: 8 Temperature: 25
4.00E-03	$mM$	Human	Expression Vector: Cerebrospinal Fluid Enzyme: PGDS pH:10 Temperature: Unspecified

Enzyme Turnover Numbers

Value	Units	Species	Notes	Reference
158.4	per minute	Human	Expression Vector: Human Cell Enzyme: PGDS pH: 8 Temperature: 25

PGDS Abundance

Value	Units	Species	Notes	Reference
156	$ppm$	Human	Expression Vector: Pancreas Enzyme: PGDS pH: 7.5 Temperature: 37 °C
101	$ppm$	Human	Expression Vector: Oral Cavity Enzyme: PGDS pH: 7.5 Temperature: 37 °C
67.9	$ppm$	Human	Expression Vector: Esophagus Enzyme: PGDS pH: 7.5 Temperature: 37 °C
44.5	$ppm$	Human	Expression Vector:Skin Enzyme: PGDS pH: 7.5 Temperature: 37 °C

Gibbs Free Energy Change

Value	Units	Species	Notes	Reference
	$kJ/mol$	Human	Expression Vector: E. Coli Enzyme: L-PGDS pH: 8 Temperature: 25
5.72	kcal/mol	Not stated	Estimated Enzyme: PGDS Substrate: Arachidonate Product: PGD2 pH: 7.3 ionic strength: 0.25

Related Reactions

• Transformation of AA to PGH2
• Transformation of PGD2 to PGJ2