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[23] Buffers of constant ionic strength for studying pH-dependent processes

1982; Academic Press; Linguagem: Inglês

10.1016/s0076-6879(82)87025-0

1557-7988

Keith J. Ellis, John F. Morrison,

Free Radicals and Antioxidants

This chapter outlines the procedures for calculating (a) the practical pKa values that apply to the buffer components under the chosen experimental conditions and (b) the ionic strength of reaction mixtures at various pH values and hence the amount of inert electrolyte that must be added to maintain the ionic strength constant. It also draws attention to the composition of two- and three-buffer systems that can be used over a wide pH range and whose ionic strength is essentially independent of pH. Although the basic theory relating to ionic strength is well known to physical chemists, it is not as familiar to biochemists. It is for this reason that a somewhat detailed presentation of the theory is given. Emphasis is placed on the use of pH studies for investigating enzyme-catalyzed reactions, but the same principles apply in connection with binding and other thermodynamic studies.