Table I.

Content, carbamylation, and kinetic parameters for Leu-335 (wild type) and Val-335 Rubiscos measured in vivo and in vitro

Parameter	In Vivo		In Vitro
	Leu-335	Val-335a	Leu-335b	Val-335a
Measured parameters
Rubisco content (μmol m−2)c	30.3  ± 1.6b	33.0  ± 5.6	n.a.	n.a.
% Carbamylationc	48.1  ± 5.6b	89.9  ± 5.4	n.a.	n.a.
Vcmax (s−1)	3.53d	1.02	3.43  ± 0.12	0.81  ± 0.04
Km(CO2) (μm)	8.6de–13.5df	8.6e–10.6f	10.7  ± 0.6	5.1  ± 0.8
Ki(O2) (μm)	226de–313df	55e–70f	295  ± 71	48.9  ± 11.5
Km (ribulose-P2) (μm)g	n.a.	n.a.	18.8  ± 3.2	2.1  ± 0.2
Sc/o	102.0d	27.0h	81.1  ± 1.6	20.1  ± 1.5
Calculated parameters
Vomax (s−1)i	n.a.	n.a.	1.17	0.39
Vcmax/Kc (mm−1 s−1)	n.a.	n.a.	321	159
Vomax/Ko (mm−1 s−1)	n.a.	n.a.	3.95	7.90
Net CO2 uptake in air (s−1)j	n.a.	n.a.	0.82	0.04
Net CO2 uptake in 0.3% (v/v) CO2 (s−1)j	n.a.	n.a.	2.80	0.57

n.a., Not applicable.

^aMeasurements with T₀ transformants. 

^bMeasurements with wild-type regenerants. 

^cMeasured with leaves sampled under the 0.3% (v/v) CO₂ growth conditions. 

^dMeasurements with anti-rbcS tobacco cv W38 taken from von Caemmerer et al. (1994). 

^eAssuming a value of 0.3 mol m⁻² s⁻¹ bar⁻¹ for the conductance for CO₂ transfer between the intercellular air spaces and the sites of carboxylation (von Caemmerer et al., 1994). 

^fAssuming infinite conductance for CO₂ transfer between the intercellular air spaces and the sites of carboxylation. 

^gFor the carboxylase reaction. 

^hEstimated from the slope of the line in the Figure 6B legend. 

ⁱV_omax = (V_cmax · K_o)/(K_c · S_c/o). 

^jNet CO₂ uptake (per carbamylated Rubisco site) from combined photosynthesis and photorespiration (neglecting nonphotorespiratory CO₂ release, i.e. R_d = 0) calculated at 25°C from the in vitro data using Equation 1 and assuming that the CO₂ concentration in the chloroplast is 8 μm in air and 94 μm in 0.3% (v/v) CO₂.