TABLE 2.

Purification of recombinant BIIb expressed from pmIFc2-BIIb from E. coli^a

Purification step	Total protein (mg)b	Amt of protein of interest (mg)c	Yield (%)d
Crude extractse	1,280	665	100
Inclusion bodies	950	632	95
Cation-exchange chromatography	126	117	18
HPLC	100	100	15

^aAll of the values were the average of five independent experiments.

^bThe amounts of total proteins in the crude extracts and inclusion bodies (resuspended in Tris-HCl buffer) were determined with the BCA protein assay using bovine serum albumin as a standard. The proteins after Resource 15S cation-exchange chromatography and reversed-phase HPLC were quantified with the LavaPep peptide quantification kit.

^cThe amounts of mIF2-BIIb protein complexes in the crude extracts and inclusion bodies, and the amounts of BIIb after Resource 15S cation-exchange chromatography and reversed-phase HPLC were also determined by quantifying the protein bands of SDS-polyacrylamide gels by densitometry at 600 nm.

^dThe yields were calculated based on the amount of the protein of interest.

^eThe starting material for purification was a crude extract obtained by cell lysis of 1 liter of IPTG-induced E. coli culture as described in Materials and Methods.