Figure 1.

Purification and ¹⁴C-NEM modification of carboxylase. Carboxylase purified in the absence of reducing agents was assayed for enzyme activity (supplemental data, Methods) and modified with ¹⁴C-NEM (Materials and Methods). Duplicate aliquots were loaded on the PhosphorImager gel for quantitation of radioactivity. ¹⁴C-BSA standards were processed in parallel (not shown) to quantitate the amount of ¹⁴C-NEM incorporation (907 cpm in the band) into a known amount of carboxylase activity (1.5 × 10^-4 μmol/min). The preparation shown here also was analyzed by amino acid analysis.