The interaction of hemerythrin with sodium dodecyl sulfate and the release of iron from the product with desferrioxamine B.

The interactions with sodium dodecyl sulfate (SDS) of methemerythrin, the anionic derivatives and oxyhemerythrin from Phascolopsis gouldii have been examined at 25 degrees C, I = 0.5 M and pH 6.3 and 7.8. Absorbance changes in the 350-500 nm range were used to monitor the rates. The denaturation is slow (k = 10(-2)-10(-3) s-1) and only slightly dependent on SDS concentration. Perchlorate is a very effective inhibitor of the SDS reaction with methemerythrin, and it is concluded that rapid binding of SDS near to the cysteine-50 site is an essential to unfolding. Myohemerythrin (from Themiste zostericola) and the monomeric N-ethylmaleimide derivatives of methemerythrin from P. gouldii and T. zostericola, in contrast, react rapidly with SDS. The products from denaturing of all proteins appear similar, having reduced alpha-helix content, very small absorbance in the 350-500 nm region and loss of anion or oxygen binding capacity. They do, however, retain the two irons, which can readily be removed with desferrioxamine B.