Purification
Metal chelation chromatography was performed utilizing the
hexahistidine fusion tag added to the N-terminus of PTRHD1. From
this single chromatography step, PTRHD1 was purified to greater
than 90% as determined from Coomassie stained SDS-PAGE band
intensity analysis (Fig. 1C). It should be noted that elution of
PTRHD1 required 250 mM imidazole, or nearly a two-fold increase
compared to other Pth proteins similarly expressed and purified
[15,17,18]. Table 1 indicates the purity of and yield of soluble
PTRHD1 with the final yield of PTRHD1 of approximately 9 mg per
gram wet weight cells.