Knowledge of cytosolic pH (pHi) is essential in many cellular studies. The most popular indicator for studying pHi is BCECF (Figure 7.5). Its pKa of 6.98 is ideal because all cells have pHi near 7.0, with physiological changes of no more than a few tenths of a pH unit. BCECF has an excitation spectrum with a maximum at 507 nm and an isoexcitation point at 438 nm (at which the fluorescence emission is independent of pH). Intracellular pH can therefore be estimated by measuring the ratio of the fluorescence intensities at 500 and 450 nm. We offer BCECF in the form of cell-impermeable free acid and the cell-permeable acetoxymethyl esters. (See Table 7.3)
DATA
Excitation: 500/450 nm (hi/low pH)
Emission: 531 nm
pKa: 7
Solubility: DMSO (AM form), H2O (salt form)
Molecular weight: 821 g/mol (AM form), 520 g/mol (salt form)
RESULTS
Figure 7.5 BCECF
