Purification of the GPT from Maize Endosperma
| Preparation | Protein (mg) | Total Transport Activity (nmol min−1) | Specific Transport Activity (nmol mg−1 min−1) | Purification (-fold) |
|---|---|---|---|---|
| Tissue homogenate | 1275 | 1350 | 1.1 | 1 |
| Membrane fraction after sucrose density flotation centrifugation | 10.4 | 27.4 | 2.7 | 2.5 |
| Chromatography on Hi Trap Q-Heparin–Sepharose CL-6B | 0.025 | 5.8 | 232 | 211 |
↵a Thirty-five grams of maize endosperm was used as the starting material, homogenized, and processed as described in Methods. Aliquots of each fraction were used for protein determination and for reconstitution into liposomes that had been preloaded with 25 mM Glc6P. 32P-phos-phate transport was measured as described in Methods.