Enhancement of productivity of recombinant alpha-amidating enzyme by low temperature culture.

We have produced a recombinant C-terminal alpha-amidating enzyme (799BglIIalpha-AE) derived from Xenopus laevis by culturing a CHO cell line named 3mu-1S. Recently, we demonstrated that culturing 3mu-1S cells at a temperature below 37 degrees C led to the following phenomena: inhibited cell growth with high viability, enhanced cellular productivity (maximally at 32 degrees C), and suppressed medium consumption and release of impurities from the cells. Therefore, it is suggested that the 799BglIIalpha-AE production will be increased by culturing a sufficient number of the cells at a low temperature (especially at 32 degrees C). To assess this effect on batch and perfusion cultures, the culture temperature was shifted from 37 to 32 degrees C in the mid-exponential phase in the case of batch culture and from 37 to 34 degrees C when the cell density became high enough in the case of perfusion culture. Application of the low temperature culture to batch and perfusion cultures was effective in comparison with the culture at 37 degrees C: the productivity per medium and the productivity per time were increased severalfold with enhanced cellular productivity at a low culture temperature. The low temperature culture also increased the relative content of 799BglIIalpha-AE in the supernatant and reduced the glucose consumption. The method presented here would contribute to production of bioactive proteins using other recombinant cell lines.