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. 1977 Aug 15;166(2):301–304. doi: 10.1042/bj1660301

Effect of endotoxin on tryptophan pyrrolase and delta-aminolaevulinate synthase: evidence for an endogenous regulatory haem fraction in rat liver.

D M Bissell, L E Hammaker
PMCID: PMC1165006  PMID: 911321

Abstract

Endotoxin was administered to rats at a dose shown previously to stimulate hepatic haem oxygenase activity and to block induction of delta-aminolaevulinate synthase, apparently by causing redistribution of haem from cytochrome P-450 to a regulatory haem pool in the liver. Within 5h of the administration of endotoxin (at a time when the effect of the compound on cytochrome P-450 is maximal) the relative saturation of tryptophan pyrrolase with intrinsic haem rose, from a basal value of 50% to 90%, indicating that 'free' haem had become available. Concurrently, the activity of delta-aminolaevulinate synthase was decreased to 25% of its basal value. Haem oxygenase reached peak activity 13h after endotoxin administration. These findings provide new evidence for the existence of an 'unassigned' hepatic haem fraction, which exchanges with cytochrome P-450 haem and regulates these three enzyme functions.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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