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. Author manuscript; available in PMC: 2016 Oct 27.
Published in final edited form as: Adv Enzyme Res. 2014 Mar;2(1):39–48. doi: 10.4236/aer.2014.21004

Figure 4.

Figure 4

Changes in absorbance associated with cleavage of methotrexate (MTX) by PGH. Panel A. Wavelength scans of MTX before (dotted line) and after (solid line) reaction with PGH. The reaction mixture included 50 mM Tris buffer, pH 7.3, 1 mM MnCl2, and 100 µM MTX. A wavelength scan was taken before and immediately after addition of enzyme; these two scans were indistinguishable. The reaction was initiated with the addition of PGH (44 µg). The reaction mixture was incubated for one hour at room temperature, and then the final scan was taken. Panel B. Difference spectrum, magnified between 310 nm and 330 nm. The point of maximal difference, which was used for continuous assays of MTX cleavage, in indicated by an arrow.