• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1938-1944
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• 2008

The procpb gene encoding human procarboxypeptidase B (proCPB, GeneBank access code AJ224866) was cloned and its Pichia expression plasmid, $pPIC9{\alpha}$/hproCPB (9.2 kb), was constructed, in which procpb was under the control of the AOXl promoter and connected to the downstream of the mating factor ${\alpha}$-1 ($MF{\alpha}1$) signal sequence. The plasmid was linearized by digestion with Sacl, and integrated into the genome of P. pastoris strain GS115. By culturing of Pichia transformant on methanol medium, the human proCPB was successfully expressed and secreted into the culture supernatant. Moreover, Western blot analysis of the extracellular proteins showed proCPB bands clearly at a molecular mass of 45 kDa, confirming the expression of proCPB with its right size. The CPB activity reached about 3.5 U/ml and 12.7 U/ml in the flask and fermentor batch cultures of Pichia transformant, respectively. No CPB enzyme activity was found in the intracellular fraction. When the fed-batch cultivation was performed with methanol and glycerol mixture as a feeding medium, the extracellular CPB activity was increased to 42.0 U/ml, which corresponds to a 3.3-fold higher level of CPB activity than that of batch culture. The $K_m$ and $k_{cat}$ values of recombinant human CPB enzyme for hippuryl-$_L$-Arg as a substrate were estimated to be 0.16 mM and $11.93\;sec^{-1}$, respectively.

• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.59.2-59.2
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• 2007

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• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.49-54
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• 2008

The gene encoding human pancreatic pro-carboxypeptidase B (CPB) was cloned and fused to Saccharomyces cerevisiae mating factor alpha-1 secretion signal $(MF{\alpha}1)$, in which the transcription of $MF{\alpha}1$-pro-CPB was under the control of GAL10 promoter. The constructed plasmid $pY{\alpha}$-hproCPB(7.72 kb) was transformed into S. cerevisiae 2805. The recombinant human pro-CPB (hproCPB) was successfully expressed in S. cerevisiae after induction of galactose, and could be secreted into the culture medium. By analyses of SDS-PAGE and western blotting, the molecular weight of the purified hproCPB was estimated to be a 45.9kDa. The activity of extracellular hCPB after removal of pro-region by trypsin treatment reached about 10.16 unit/ml at batch culture of S. cerevisiae $2805/pY{\alpha}$-hproCPB for 60 h. Also, the Km value of partially purified recombinant hCPB is about 0.43 mM.