Effects of hemin and porphyrin compounds on intersubunit disulfide formation of heme-regulated eIF-2 alpha kinase and the regulation of protein synthesis in reticulocyte lysates.

摘要: To study the mechanism by which heme regulates heme-regulated eIF-2 alpha kinase (HRI), effects of various protoporphyrin IX (PP) compounds on activities and intersubunit disulfide formation HRI protein synthesis in reticulocyte lysates were examined. Hemin cobalt (CoPP) are more effective than ZnPP, NiPP, SnPP, metal-free PP promoting bond HRI, inhibiting autokinase phosphorylation rabbit reticulocytes, maintaining synthesis, reversing inhibition deficiency. There is an apparent correlation vitro regulation these porphyrin compounds. lysate can be cross-linked 1,6-bismaleimidohexane (bis-NEM). The bis-NEM dimers prevented completely N-ethylmaleimide (NEM) alkylates free sulfhydryl groups diminished hemin CoPP. These results support view that hemin-supplemented equilibrium between noncovalently linked dimer disulfide-linked dimer. molecular size control, hemin-supplemented, or NEM-treated identical to purified HRI; activation changes its thiol status do not significantly affect size.