Table 6.

pH of maximum stability, pHmax and isoelectric points of some well-studied proteins

Protein	pHmax	Experimental pI	Calculated pIa
Pepsin	—	2.9b	3.2
RNase Sa	∼5.0c,d	3.5c,e	4.4
RNase T1	4–5	3.8e	4.3
β-Lactoglobulin	—	5.1b	4.8
RNase Sa2	∼4.5d	5.3e	7.4
RNase Sa (3K)	4–5c	6.4c	6.6
RNase Sa3	∼5.5d	7.2e	6.2
Whale myoglobin	∼6.5g	8.0b	8.4
RNase Ba	5–6h	9.2i	9.0
Horse cytochrome C	∼7.5j	9.4b	9.7
RNase A	7–9f	9.6b	9.3
Chymotrypsinogen A	—	9.6b	9.4
Staph nuclease	∼9.0k	>10.0k	9.7
RNase Sa (5K)	∼5.0c	10.2c	9.1
Human lysozyme	∼4.5l	10.5b	10.3
T4 lysozyme	∼5.5m	>10.5n	10.0
BPTI	∼5.0o	10.6b	10.2
Hen lysozyme	5–7p	11.2b	10.5

^a Calculated using pK values determined from model compound studies as described in footnote b of Table 1.^b From Table 3 of Patrickios and Yamasaki (1995).^c From this paper.^d From Pace et al. (1998).^e From Hebert et al. (1997).^f From Pace et al. (1990).^g From Puett (1973).^h From Pace et al. (1992).ⁱ From Bastyns et al. (1996).^j From Walter Englander, personal communication.^k From Whitten and Garcia-Moreno (2000).^l From Takano et al. (2000).^m From Dao-pin et al. (1991).ⁿ From Becktel and Base (1987).^o From Makhatadze et al. (1993).^p From Pfeil and Privalov (1976) and Schaefer et al. (1998).