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. Author manuscript; available in PMC: 2011 Jul 6.
Published in final edited form as: Biochemistry. 2010 Jul 6;49(26):5405–5407. doi: 10.1021/bi1007194

Figure 3.

Figure 3

2-Dimensional thin layer chromatography under 302 nm ultraviolet light. Glass-backed silica gel plates were eluted in two directions: first horizontally with ethyl acetate, then vertically with 96% chloroform, 4% methanol. (A) N,N′-dimethyl-p-phenylenediamine (DMPD) standard. Rf,1 = 0.45, Rf,2 = 0.2 (B) 2-aminobenzoic acid (ABA) standard. Rf,1 = 0.68, Rf,2 = 0.12 (C) Chloroform extract of the supernatant from M9 minimal media E. coli culture after color change. Red and yellow arrows indicate locations predicted for spots from DMPD and ABA respectively. The white arrow indicates where Methyl Red would appear on the plate if it were present. A spot corresponding to ABA is evident. However, the DMPD spot is difficult to detect under UV light. Nonetheless, when plates A and C were allowed to sit at room temperature it was seen (not shown) that the DMPD spot of plate A turned brown and that a brown spot also appeared on plate C at the expected location for DMPD (red arrow).