H+ titration studies of human hemoglobin

The fatty-acid-induced conformational states of human serum albumin investigated by means of multiple co-binding of protons and oleic acid

“…Positive AZ3 values indicate that the pK values in protein and/or fatty acid shift to higher values when oleic acid is added, whereas negative AZ3 values indicate a shift to lower values (Janssen et al, 1970;Janssen & Van Wilgenburg, 1978;Droge et al, 1983). Fig.…”

“…Each time the oleic acid was added, the pH of the albumin solution was subsequently titrated back to its original value. The difference between the protonic charge of the albumin in the presence and in the absence of oleic acid (AZ3) can be calculated (Janssen et al, 1970;Janssen & Van Wilgenburg, 1978) from the amount of KOH or HCI needed to bring the pH back to its original value. The pH-stat experiments were done at 25°C.…”

The interaction of 2,3-diphosphoglycerate on human deoxy and oxyhemoglobin

“…In order to be able to measure the several proton exchange processes we developed a very accurate pH stat equipment as an extension to the titration equipment we described earlier (13). It would go beyond the scope of this paper to describe this pH stat equipment in detail; suffice it to say that the rate of revolution of the burette motor is linearly prportional to deviations from any particular fixed p H value.…”

pK change of imidazole groups in bovine serum albumin due to the conformational change at neutral pH

“…Differential titration curves were determined as described by De Bruin and Van Os (1968) and Janssen et al (1970). The solutions were brought to the desired ionic strength with KC1 or CaCl2 and titrated under nitrogen with carbonate-free NaOH at 24.9 or 5.0 ± 0.05°.…”