High Level Expression, Purification and Characterization of Human Kallikrein-1 in Pichia pastoris
人激肽释放酶-1在甲醇酵母中高水平表达、纯化与鉴定

Human kallikrein-1 (hK1) gene was cloned from kidney tissues cDNA, it was inserted into the plasmid pPICZaA, then the yeast expression vector pPICZa-hK1 was constructed. After transformed into Pichia pastoris host X33, high-level expression transformants were screened by escalating the concentration of Zeocin (from 500 to 700 mg/mL) of YPD plate and medium. When temperature was 30oC, pH 6.0 with induction duration of 64 hours in the 30 L fermenter, the highest yield can reach about 6500 u/L (1.25 g/L). The variation of glycosylation resulted in two kinds of molecules, i.e. rhK1-H with a heavy molecular weight and rhK1-L with a light one. rhK1 was purified from the supernatant through Phenyl hydrophobic interaction, Cu2+-charged Chelating and Anion-exchange chromatography. 0.28 g rhK1-H and 0.62 g rhK1-L can be purified from one liter supernatant. The yield recovery was 72% with a purity of >96%. So far our yield of rhK1 is superior than known recombinant expression method reported by other researchers.