Cystalysin, a 46-kDa
protein isolated from the cytosol of Treponema denticola, was capable of both
cysteine dependent hemoxidation and
hemolysis of human and sheep red blood cells. The activities were characteristic of a
cysteine desulfhydrase.
Sodium dodecyl sulfate-
polyacrylamide gel electrophoresis (SDS-PAGE) and Western immunoblotting analysis of the interaction of
cystalysin with the red blood cells revealed an interaction of the
protein with the red blood cell membrane. Substrates for the
enzyme (including
L-cysteine and
beta-chloroalanine) enhanced the interaction, which occurred with both whole red blood cells as well as with isolated and purified red blood cell ghosts. SDS-PAGE and western immunoblotting employing anti-
hemoglobin serum revealed that, during the hemoxidative events, the
hemoglobin molecule associated with the red blood cell membrane, forming putative Heinz bodies. Spectrophotometric analysis of the hemoxidative events (
cystalysin +
cysteine + red blood cells) revealed a chemical modification of the native
hemoglobin to
sulfhemoglobin and
methemoglobin. Hemoxidation also resulted in the degradation of both the red blood cell alpha- and
beta-spectrin. The results presented suggest that the interaction of
cystalysin with the red blood cell membrane results in the chemical oxidation of the
hemoglobin molecule as well as an alteration in the red blood cell membrane itself.