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. Author manuscript; available in PMC: 2014 Jun 10.
Published in final edited form as: Chem Biol. 2009 Sep 25;16(9):1013–1020. doi: 10.1016/j.chembiol.2009.08.009

Figure 4.

Figure 4

Use of the amino terminal His-tag: Ni-NTA attachment chemistry improved binding and the specific activity of the GPI relative to GPI randomly adsorbed to the surface. The His-tag was cleaved from His-GPI by means of an enterokinase site provided by the vector. (A) Approximately twice as much His-GPI bound to a Ni-NTA support in comparison with control GPI lacking the His-tag (p=0.012, paired student T test; n = 9 samples, with 3 samples from each of 3 protein preparations. Bars indicate the standard deviations.). (B) Normalizing for the amount of protein bound allowed a quantification of the specific activities of the adsorbed proteins. The specific activity of the His-GPI was approximately 9 times greater than that of the randomly absorbed GPI, although the enzyme activities in solution were relatively equal (p=0.006, paired student T test; n = 9 samples, with 3 samples from each of 3 protein preparations. Bars indicate the standard deviations.).