Characterization of 6-phosphofructo-2-kinase from foetal-rat liver.
Foetal and adult liver 6-phosphofructo-2-kinase (PFK-2) were purified by identical protocols. The native molecular masses of both enzymes were determined by gel filtration and were 89.1 and 100.0 kDa respectively. No differences were found in SDS/PAGE in 10%-acrylamide gel (55 kDa per subunit). The kinetic properties displayed by both enzymes were similar, except for the sensitivity to inhibition by sn-glycerol 3-phosphate. Foetal PFK-2 was a good substrate for phosphorylation by cyclic AMP-dependent protein kinase and protein kinase C, whereas the adult enzyme was phosphorylated only by cyclic AMP-dependent protein kinase. However, the phosphorylation affected only the kinetic properties of the adult enzyme, suggesting the presence in both enzymes of different sites of phosphorylation by cyclic AMP-dependent protein kinase. These differences in primary structure were consistent with the distinct chromatographic profiles of the phosphopeptides after digestion of the protein with CNBr. Western-blot analysis with antibodies specific for the N-terminal region of the liver-type PFK-2 poorly recognized the foetal enzyme, suggesting that both enzymes differ at least in the N-terminal sequence.
Martín-Sanz
P
P
Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
Cascales
M
M
Boscá
L
L
D000375:Aging / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D008099:Liver / Q000196:embryology / Q000201:enzymology*; D025481:Phosphofructokinase-2; D010766:Phosphorylation; D010770:Phosphotransferases / Q000737:chemistry / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013438:Sulfhydryl Compounds / Q000737:chemistry
D013438:Sulfhydryl Compounds; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D003488:Cyanogen Bromide