Biomaterial Database

Regulation of rat liver tryptophan pyrrolase by its cofactor haem: Experiments with haematin and 5-aminolaevulinate and comparison with the substrate and hormonal mechanisms. 1975

A A Badawy, and M Evans

1. The administration of haematin or 5-aminolaevulinate to rat enhances the activity of liver tryptophan pyrrolase; both endogenous and newly formed apoenzymes become strongly haem-saturated. Haem activation does not stabilize tryptophan pyrrolase. 2. Actinomycin D, puromycin or cycloheximide prevent the activation of the enzyme by 5-aminolaevulinate but not that by haematin. The latter is inhibited by haem-destroying porphyrogens. 3. The combined injection of either haematin or 5-aminolaevulinate with cortisol does not produce an additive effect, whereas potentation is observed when tryptophan is jointly given with either the cofactor or the haem precursor. 4. Further experiments on the substrate (tryptophan) mechanism of pyrrolase regulation are reported, and a comparison between this and the cofactor and hormonal mechanisms is made. 5. It is suggested that the substrate mechanism may also involve increased haem synthesis. 6. The role of tryptophan pyrrolase in the utilization of liver haem, and as a possible model for the exacerbation by drugs of human hepatic porphyrias, is discussed.

UI	MeSH Term	Description	Entries
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D011164	Porphyrias	A diverse group of metabolic diseases characterized by errors in the biosynthetic pathway of HEME in the LIVER, the BONE MARROW, or both. They are classified by the deficiency of specific enzymes, the tissue site of enzyme defect, or the clinical features that include neurological (acute) or cutaneous (skin lesions). Porphyrias can be hereditary or acquired as a result of toxicity to the hepatic or erythropoietic marrow tissues.	Porphyria,Porphyrin Disorder,Disorder, Porphyrin,Disorders, Porphyrin,Porphyrin Disorders
D011165	Porphyrinogens	Colorless reduced precursors of porphyrins in which the pyrrole rings are linked by methylene (-CH2-) bridges.
D011691	Puromycin	A cinnamamido ADENOSINE found in STREPTOMYCES alboniger. It inhibits protein synthesis by binding to RNA. It is an antineoplastic and antitrypanosomal agent and is used in research as an inhibitor of protein synthesis.	CL-13900,P-638,Puromycin Dihydrochloride,Puromycin Hydrochloride,Stylomycin,CL 13900,CL13900,P 638,P638
D003513	Cycloheximide	Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis.	Actidione,Cicloheximide
D003609	Dactinomycin	A compound composed of a two CYCLIC PEPTIDES attached to a phenoxazine that is derived from STREPTOMYCES parvullus. It binds to DNA and inhibits RNA synthesis (transcription), with chain elongation more sensitive than initiation, termination, or release. As a result of impaired mRNA production, protein synthesis also declines after dactinomycin therapy. (From AMA Drug Evaluations Annual, 1993, p2015)	Actinomycin,Actinomycin D,Meractinomycin,Cosmegen,Cosmegen Lyovac,Lyovac-Cosmegen,Lyovac Cosmegen,Lyovac, Cosmegen,LyovacCosmegen
D006397	Hematinics	Agents which improve the quality of the blood, increasing the hemoglobin level and the number of erythrocytes. They are used in the treatment of anemias.	Erythropoiesis Stimulating Agent,Hematinic,Hematopoietic Agents,Erythropoiesis Stimulating Agents,Agent, Erythropoiesis Stimulating,Stimulating Agent, Erythropoiesis
D006418	Heme	The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.	Ferroprotoporphyrin,Protoheme,Haem,Heme b,Protoheme IX
D006854	Hydrocortisone	The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions.	Cortef,Cortisol,Pregn-4-ene-3,20-dione, 11,17,21-trihydroxy-, (11beta)-,11-Epicortisol,Cortifair,Cortril,Epicortisol,Hydrocortisone, (11 alpha)-Isomer,Hydrocortisone, (9 beta,10 alpha,11 alpha)-Isomer,11 Epicortisol
D000622	Aminolevulinic Acid	A compound produced from succinyl-CoA and GLYCINE as an intermediate in heme synthesis. It is used as a PHOTOCHEMOTHERAPY for actinic KERATOSIS.	5-Amino Levulinic Acid,5-Aminolaevulinate,5-Aminolevulinate,Aminolevulinic Acid Hydrochloride,Delta-Aminolevulinic Acid,Levulan,5 Amino Levulinic Acid,5 Aminolaevulinate,5 Aminolevulinate,Acid Hydrochloride, Aminolevulinic,Acid, 5-Amino Levulinic,Acid, Aminolevulinic,Acid, Delta-Aminolevulinic,Delta Aminolevulinic Acid,Hydrochloride, Aminolevulinic Acid,Levulinic Acid, 5-Amino