Fig. 6.

Purification of recombinant proline-4-hydroxylase (Phy1) and optimization of Hyp production. A: SDS-PAGE analysis of Phy1 purification. Lane 1, molecular mass standards (kDa); lane 2, Escherichia coli cell extract at 0-h induction; lane 3, cell extract after 3-h induction with isopropyl β-d-1-thiogalactopyranoside; lane 4, cell extract after 6-h induction; lane 5, purified Phy1 containing the NH₂-terminal His tag; lane 6, purified Phy1 after removal of the His tag. B: reaction curves for Phy1 at 0.1 mg/ml (▵), 0.4 mg/ml (○), and 1.2 mg/ml (□). C: purification of Hyp from Pro via AG 50W-X8 column chromatography. □, Hyp-containing peaks; ■, Pro- containing peaks.