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Logo of ambexSpringerOpen.comThis journalSubmit a manuscriptRegisterSpringerOpen.comAMB Express
AMB Express. 2012; 2: 14.
Published online 2012 February 29. doi:  10.1186/2191-0855-2-14
PMCID: PMC3306196

High level expression of bikunin in Pichia pastoris by fusion of human serum albumin


Bikunin is a proteoglycan exhibiting broad-spectrum inhibitory activity against serine proteases and could potentially suppress tumor cell invasion and metastasis. Here, we have successfully expressed recombinant human bikunin (rh-bikunin) in Pichia pastoris and also established the purification procedure. Different fusion genes of h-UTI and domain I, domain I and domain II, domain I, domain II and domain III of human serum albumin (HSA) were inserted into expression vector pPICZαA. After expressed in shake flask, rh-bikunin was produced in an 30-L fermenter and purified by affinity chromatography and cation exchange chromatography. The final expression levels were 200 mg/L and we got totally 1.08 g (3650 IU/mg) of active purified rh-bikunin (purity is 98%) from 20 L of fermentation broth. The rh-bikunin consists of unique form with molecular masses of 25 kDa, and has the same N-terminals sequence as human native bikunin. This study provided a new method for high level expression of active rh-bikunin by using HSA as fusion parter.

Keywords: Human bikunin, Fusion expression, Human serum albumin, Pichia pastoris

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