Fig 4. Spectral analysis of purified MPO heme ring.

(A) MPO undergoes oxidative changes when incubated with H₂O₂. PIC1 protects MPO from oxidization in the presence of H₂O₂. Spectral absorption readings were taken from 300 to 550 nm (n = 3). Data are means of independent experiments ±SEM. (B) Spectral analysis of purified MPO when incubated with PIC1 or ABAH. Spectral absorption readings were taken from 300 to 550 nm (n = 3). Data are means of independent experiments ±SEM. (C) MPO undergoes oxidative changes in the presence of bleach. PIC1 protects MPO from oxidization in the presence of bleach. Spectral absorption readings were taken from 300 to 550 nm (n = 2). Data are means of independent experiments ±SEM. (D) Fe release from MPO in the presence of bleach is inhibited by PIC1 as measured by ferrozine assay.