Figure 2.

Biochemical characteristics of the UDP-Xyl-enhanced GlcAT activity in Golgi-enriched microsomes from wheat etiolated seedlings. Microsomal membranes (approximately 0.1 mg of protein unless indicated otherwise) of 6-d-old wheat seedlings were incubated with UDP-[¹⁴C]GlcA in the presence of 0.5 mm UDP-Xyl (unless indicated otherwise) for 90 min, and the [¹⁴C]GlcA incorporation is expressed either as a percentage of the total activity in the control in a standard assay or as cpm. A and B, Effects of pH (A) and divalent cations (B) on [¹⁴C]GlcA transfer as a percentage of the optimal activity. C and D, Effects of increasing amounts of enzyme (up to 0.4 mg of protein; C) and increasing amounts of UDP-Xyl (up to 1 m; D) on wheat GlcAT activity. The cations were used at a final concentration of 5 mm.