Ontogeny of 5-aminolevulinic dehydratase and porphobilinogen deaminase activities in the yolk sac membrane and liver of chick embryos.
1. Chick embryos of 7, 9, 11, 12, 13, 14, 15, 17 and 19 d of embryonic development were examined to determine the activities of 5-aminolevulinic dehydratase (ALA-D, EC 4.2.1.24) and porphobilinogen deaminase (PBG-D, EC 4.3.1.8). 2. Liver and yolk sac membrane ALA-D specific activities showed a maximum between 12 and 13 d of embryonic development, yolk sac membrane PBG-ase activity a maximum at 9 d and at 7 d in liver. Total activities of ALA-D and PBG-D were not constant during the course of embryonic development but probably related to the changes of intensity of haem synthesis. 3. ALA-D and PBG-ase activities were higher in yolk sac membrane than in liver, showing the importance of the yolk sac membrane as erythropoietic tissue. PBG-D catalysed the rate-limiting reaction of the cytosolic steps in the biosynthetic pathway in both tissues.
Pauza
N L
NL
Departamento de Química Biológica, Facultad de Ciencias Exactas y naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, Capital Federal, Buenos Aires, Argentina.
Sopena de Kracoff
Y E
YE
Ferramola de Sancovich
A M
AM
Sancovich
H A
HA
D000367:Age Factors; D000818:Animals; D002642:Chick Embryo / Q000201:enzymology* / Q000254:growth & development; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism*; D008099:Liver / Q000196:embryology / Q000201:enzymology*; D000623:Porphobilinogen Synthase / Q000378:metabolism*; D013053:Spectrophotometry; D015017:Yolk Sac / Q000196:embryology / Q000201:enzymology*
D011163:Hydroxymethylbilane Synthase; D000623:Porphobilinogen Synthase