Studies on uroporphyrinogen decarboxylase of etiolated Euglena gracilis Z.
1. A 423-fold purified fraction of uroporphyrinogen decarboxylase (EC 4.1.1.37) showing a specific activity of 770 units/mg protein has been employed in order to study some properties in etiolated Euglena gracilis Z. 2. Uroporphyrinogen decarboxylase has a relative molecular mass of 54,000, an optimum pH of 7.2 and exhibits Michaelis-Menten kinetics, employing both uroporphyrinogen I and uroporphyrinogen III as substrates. 3. Anaerobic conditions seem not to be necessary for uroporphyrinogen decarboxylase activity. Neither EDTA nor cysteine affected enzyme activity, whereas dithiothreitol produced a remarkable activation of coproporphyrinogen formation. 4. Kinetic data employing both substrates showed an accumulation of porphyrinogen (i.e. hexa- and hepta-porphyrin) containing six or seven COOH groups, depending on the uroporphyrinogen concentration used. 5. An unusual elution profile of the intermediates on Sephacryl S-200 was found.
Juknat
A A
AA
Department of Dermatology, University of Göttingen.
Seubert
A
A
Seubert
S
S
Ippen
H
H
D000818:Animals; D002262:Carboxy-Lyases / Q000302:isolation & purification*; D004795:Enzyme Stability; D005056:Euglena gracilis / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D014575:Uroporphyrinogen Decarboxylase / Q000302:isolation & purification* / Q000378:metabolism
D002262:Carboxy-Lyases; D014575:Uroporphyrinogen Decarboxylase