Concentration Ms/M

Cameron et al, 1990, 1997; Fullerton et al., 1992, 2006a,b; Kanal et al., 1994; Zimmerman et al., 1994, 1995) while the constant in the linear equation accurately measures henc, the total hydration encapsulated by the protein. Studies of BSA under nonphysiologic conditions showed that henc can be > hM when the protein expands from the compact native form into a molten globule (Kanal et al., 1994; Zimmerman et al., 1994). Thus estimates of hM from measurements of henc can be highly dependent on solution cofactors such as pH and salt as shown in Fig. 1.12 for BSA unless one selects the unique minimum value achieved by adjusting over a range of pH values (Kanal et al., 1994). The SHM and DSC measurements on collagen indicate that most encapsulated water is thermodynamically identical to bulk water. However, encapsulated water differs from bulk external water in that it never has an opportunity to participate in the bombardment of adjacent semipermeable osmotic membranes. More recently, the osmotic compression method was used to show that the water content of mammalian cells responds to cosolute factors that influence protein conformation (Cameron et al., 2006; Fullerton et al., 2006a,b). Comparison of the I value measured for hemoglobin hm — 1.7 g/g as shown in Fig. 1.12 agrees with the value for

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