Thermodynamic Parameters of Some Biochemically Significant Buffers

Abstract

Heats of proton transfer of nineteen buffer moieties have been determined by adiabatic titration calorimetry in dilute aqueous solutions. Corresponding ionization constants covering a pK range between 6 and 11 were evaluated potentiometrically. Relevant entropies of ionization were computer yielding a comprehensive tabulation of fifty-seven δH°, pK and δ° assignments, encompassing a wide variety of primary, secondary, and tertiary amine and amino acid systems. The majority of the systems included display suitable buffering capacity in the physiological pH range and are expected to be of utility in thermochemical studies of enzymatic processes.

Key Words:

• Titration
• calorimetry
• enzyme analysis
• sulfonate buffers
• clinical chemistry
• enthalpy
• entropy
• ionization constant