Changes in the state of ionization of carboxyl groups in elastin in response to the binding of sodium dodecyl sulfate.

The interaction of sodium dodecyl sulfate with elastin has been studied by complexometric titration. Approximately 1.2 mumoles of protons with a pKapp of 5.45 are taken up by 10 milligrams of insoluble elastin upon the binding of detergent, apparently due to the protonation of normally ionized carboxylate functions in this protein. Since ionized carboxylate functions of elastin are essential for its interaction with elastase and, possibly, metallic cations, these results may have physiological significance in view of the affinity of elastin for lipid-like ligands.