Characterization of mevalonate-activating enzymes in the neonatal chick liver.
1. The 5-phosphomevalonate (MVAP) and 5-pyrophosphomevalonate (MVAPP) formation by cell-free extracts from 7-10 days chick liver shows an absolute nucleotide requirement, ATP being the most effective phosphate donor, though ITP and UTP can be used less effectively. 2. Mn2+ is a better activator than Mg2+ at low concentrations (0.1-5.0 mM). At higher concentrations (10.0 mM) Mn2+ produces a clear decrease in the MVAP formation, whereas the maximum MVAPP formation occurs in the presence of 10.0 mM Mg2+. 3. Mevalonate-activating enzymes maintain their activities for 48 hr at 4 degrees C and 24 hr at 37 degrees C. No MVAP is formed when the extracts are heated to 65 degrees C for 10 min. 4. Unlike other vertebrate mevalonate and phosphomevalonate kinases, these enzymes from chick liver are not activated by -SH group protectors as dithiothreitol, reduced glutathione, cysteine or beta-mercaptoethanol. However, the enzymes are found to be sensitive to thiol binding reagents p-hydroxymercuribenzoate and 5,5'-dithiobis-(2-nitrobenzoic acid).
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002645:Chickens; D008099:Liver / Q000201:enzymology*; D008297:Male; D008798:Mevalonic Acid / Q000378:metabolism*; D010770:Phosphotransferases / Q000032:analysis*; D017853:Phosphotransferases (Alcohol Group Acceptor); D017856:Phosphotransferases (Phosphate Group Acceptor)
D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C021796:mevalonate kinase; D017856:Phosphotransferases (Phosphate Group Acceptor); C022371:phosphomevalonate kinase; D008798:Mevalonic Acid