TABLE 1.

Substrate specificity of recombinant C. reinhardtii VTC2

Various sugar nucleotides (50 μm) were incubated in the presence of C. reinhardtii VTC2 recombinant enzyme (0.025 μg ml⁻¹) for 10 min at 26 °C. With GDP-l-Gal as a substrate, the specific activity of the C. reinhardtii VTC2 enzyme was 25.4 ± 5.1 μmol min⁻¹ mg protein⁻¹ (mean ± S.D., n = 3); this value was taken as 100%. The phosphorylase activities found with the other sugar nucleotides are given as a percentage of the activity found with GDP-l-Gal ± S.D. Values represent the means of 2–3 individual experiments for each substrate.

Substrate	Relative activity of recombinant C. reinhardtii VTC2
	% ± S.D.
GDP-l-Gal	100
GDP-d-Glc	87.4 ± 29.2
GDP-l-Fuc	51.4 ± 15.1
GDP-d-Man	0 ± 0
UDP-d-Glc	0.5 ± 0.8
UDP-d-Gal	2.5 ± 4.1
ADP-d-Glc	3.7 ± 5.8