Unidirectional inhibition of phosphoenolpyruvate carboxykinase fromRhodospirillum rubrumby ATP

✍ Scribed by Jobst-Heinrich Klemme

• Book ID: 104777908
• Publisher: Springer
• Year: 1976
• Tongue: English
• Weight: 338 KB
• Volume: 107
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00446838

✦ Synopsis

The kinetic and regulatory properties of partially purified phosphoenolpyruvate (PEP) carboxykinase (EC 4.1.1.3.2) from Rhodospirillum rubrum were studied. The enzyme was active with guanosine- and inosinephosphates and must thus be classified as GTP (ITP): oxaloacetate carboxylase (transphosphorylating.) In the direction of oxaloacetate-foramtion, the enzyme was strongly inhibited by ATP (Ki = 0.03 mM). ITP, UTP, CTP, and GTP were less inhibitory. The inhibition was competitive with respect to GDP or IDP, but not with respect to PEP. In the direction of PEP-synthesis, the enzyme was not inhibited, but rather activated by ATP.