Protein purification?

W. Chen wcg8744 at
Thu Mar 31 23:47:53 EST 1994

Hi, everyone, 

My friend is trying to purify a protein from plant leaf by the following
procedure: The plant proteins were extracted by grinding the leaf in the
phosphate buffer (pH 5.8). The crude proteins were then applied to a
DEAE-Sephacyel column equilibrated with the phosphate buffer, and the
column was washed with the phosphate buffer but no proteins were eluted
out. It seemed that all of the proteins bound to the column. So the bound
proteins were eluted with a 0-1 M NaCl gradient in the phosphate buffer. It
was found that the total proteins eluted in a single sharp peak at an NaCl
concentration of 0.4 M. The fractions of the peak were pooled and subjected
to SDS-PAGE analysis and got the same pattern as the crude proteins before
DEAE-sephacyel chromatography. We don't undersdand why the proteins were
not separated by the above procedure? If you have any suggestions, please
respond me at this account. Thanks. 

W. Chen

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