Figure 4.

Molecular mass of native maize β-UP determined by size-exclusion chromatography. A sample of partially purified β-UP was applied onto a Superose 12 column (Pharmacia) equilibrated in 0.1 m potassium phosphate, pH 7.0, 1 mm MgCl₂, and 2 mm DTT at a flow-rate of 0.4 mL min⁻¹. Fractions of 0.4 mL were collected and assayed for β-UP activity. The amount of radiolabel lost from the assay as CO₂ relative to a control is shown on the left axis. The position of Bio-Rad native molecular mass standards (670, 158, 44, 17, and 1.35 kD) run under the same elution conditions is shown on the right axis.