This study investigated the effects of pH, muscle fiber type, and precursor levels on zinc protoporphyrin IX (ZnPP) formation in porcine skeletal muscles. ZnPP formation could be classified into three distinct groups with pH optima of 4.75, 5.5, or both. The effects of temperature and incubation time on ZnPP formation at the new optimal pH 4.75 differed significantly from those at pH 5.5 reported in previous studies. Protoporphyrin IX (PPIX) formation at pH 4.75 nearly coincided with that of ZnPP, suggesting that the latter strongly affects the former, as observed at pH 5.5. The amount of ZnPP formed at pH 4.75 was related to the ratio of type I muscle fibers. Although myoglobin degradation occurred at pH 4.75, no decrease in heme content corresponded to the formation of ZnPP and PPIX. These results demonstrate that ZnPP and PPIX are formed by two independent mechanisms in porcine skeletal muscles whose optimal pH values are 5.5 and 4.75.

这项研究调查了pH，肌肉纤维类型和前体水平对猪骨骼肌中锌原卟啉IX（ZnPP）形成的影响。ZnPP的形成可分为3个不同的组，最适pH值为4.75、5.5，或两者兼而有之。在新的最佳pH 4.75下，温度和孵育时间对ZnPP形成的影响与先前研究中报道的在pH 5.5上的影响显着不同。pH值为4.75时原卟啉IX（PPIX）的形成与ZnPP几乎一致，这表明在pH 5.5时后者会强烈影响前者。pH为4.75时形成的ZnPP量与I型肌纤维的比例有关。尽管肌红蛋白降解发生在pH 4.75，但血红素含量的下降并没有对应于ZnPP和PPIX的形成。