. Author manuscript; available in PMC: 2016 Feb 17.

Published in final edited form as: Biochemistry. 2015 Feb 3;54(6):1364–1370. doi: 10.1021/bi5014722

Table 3.

pK_a determination for five pH indicators and cytidine monophosphate with two different sized PEGs at 40% (w/w) in 30 mM sodium cacodylate buffer

	pK_a 4-Nitro- phenol	pK_a Bromo- thymol Blue	pK_a 3,4- Dinitro- phenol	pK_a Methyl Red	pK_a Phenol Red	pK_a Cytidine Mono- phosphate
Lit. Value^*	7.1	7.1	5.4	5.0	7.9	4.3
No PEG	7.10 ± 0.04	7.07 ± 0.03	5.31 ± 0.02	5.04 ± 0.04	7.98 ± 0.05	4.35 ± 0.06
PEG-300	7.33 ± 0.04	7.35 ± 0.04	5.52 ± 0.04	5.32 ± 0.03	8.27 ± 0.02	4.57 ± 0.04
PEG-3350	7.35 ± 0.06	7.36 ± 0.04	5.53 ± 0.02	5.28 ± 0.03	8.25 ± 0.02	4.61 ± 0.02
ΔpKa	0.24	0.28	0.22	0.26	0.28	0.24
ΔpKa (Avg.)	0.25 ± 0.03

References^50-55