TABLE 2.

Kinetic characteristics of P(3HB) biosynthetic enzymes

Enzyme and species	Km (mM)	Substrate	Product	Reference
Thiolase (condensation)
Z. ramigera	0.33	Acetyl-CoA	Acetoacetyl-CoA	35
Thiolase (thiolysis)
Z. ramigera	0.024	Acetoacetyl-CoA	Acetyl-CoA	35
	0.46	Acetoacetyl-pantheteine	Acetyl-CoA + acetyl-pantheteine	35
	0.073	Acetoacetyl-pantheteine-11-pivalate	Acetyl-CoA + acetyl-pantheteine-11-pivalate	35
	(50%)a	3-Ketovaleryl-CoA	Acetyl-CoA + propionyl-CoA	166
R. eutropha	0.044	Acetoacetyl-CoA	Acetyl-CoA	252
	(3%)b	3-Ketovaleryl-CoA	Acetyl-CoA + propionyl-CoA	252
	(0%)b	3-Ketohexanoyl-CoA	Acetyl-CoA + butanoyl-CoA	252
NADPH-dependent reductase
Z. ramigera	0.002	Acetoacetyl-CoA	3-Hydroxybutyryl-CoA	198
	0.002	3-Ketovaleryl-CoA	3-Hydroxyvaleryl-CoA	198
	0.010	3-Ketohexanoyl-CoA	3-Hydroxyhexanoyl-CoA	198
	0.99	Acetoacetyl-pantheteine-11-pivalate	3-Hydroxybutyryl-pantheteine-11-pivalate	198
R. eutropha	0.005	Acetoacetyl-CoA	3-Hydroxybutyryl-CoA	252
	(18%)b	3-Ketovaleryl-CoA	3-Hydroxyvaleryl-CoA	252
	(3.6%)b	3-Ketohexanoyl-CoA	3-Hydroxyhexanoyl-CoA	252
P(3HB) polymerase
R. eutropha	0.72	3-Hydroxybutyryl-CoA	P(3HB)	252
	1.63	3-Hydroxyvaleryl-CoA	PHV	252
	NDc	3-Hydroxybutyryl-pantheteine-11-pivalate	None	69

^aV_max with respect to acetoacetyl-CoA. 

^bRelative activity with respect to acetoacetyl-CoA and 3-hydroxybutyryl-CoA. 

^cND, not determined.