FIG 3.

Trypsin digestion of rCPB variants. Recombinant CPBs containing JGS1076 or CN3685 sequences were constructed in pGEX-2T as GST fusion proteins. Site-directed mutagenesis was performed on the CN3685 rCPB variant, individually switching each of the 4 amino acids that differ between CN3685 CPB and JGS1076 CPB to the amino acids present in the JGS1076 sequence. Purified rCPB (50 μg/ml) from each of those variant rCPBs was then digested with trypsin in HBSS. Western blotting and densitometry were performed to determine the amounts of rCPB remaining relative to the starting amounts. The times for 50% digestion from four replicate digests are presented. Error bars indicate standard errors of the means. #, there was a significant (P < 0.05) difference from the results for the CN3685 variant rCPB. *, there was a significant (P < 0.05) difference from the results for the JGS1076 variant rCPB.