Formation of Zinc Protoporphyrin IX form Myoglobin with Pork Loin Extract

Abstract

The formation of zinc protoporphyrin IX (ZPP) with pork loin extract wa determined by visible absorption and fluorescent spectral analyses. Arter the anaerobic incubation (in the dark at pH 5.5 and 30'C) of the extract with metmyoglobin and ZnCL,, characteristic peaks in absorption and spectra were observed at 417, 546, and 584 nm. In fluorescent spectra, a peak was observed at 589nm. Formed amounts of ZPP estimated from the fluorescent intensity at 589 nm was 15.5 nmoVmL-pork extract. The difference in the formations of ZPP under aerobic and anaerobic incubations was not significant. The ZPP formation was significantly facilitated by the use of ATP. Zinc chelatase activity of loin extract was assayed wlth protoporphyrin IX and it was estimated as 42 mU/ml;extract. The Fe-Zn substituting activity of the extract was assayed wlth myoglobin as a substrate. Under the assay conditions at pH 5.5 and 40 'C, ZPP was markedly increased with increasing time by using oxymyoglobin reduced with ascorbate, while little increase was observed with metmyoglobin. The activity was estimated as 4.ImU/mL-extract with oxymyoglobin. At pH 5.5-7.0, higher activities were observed at lower pH.