Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the reactions of carboxylation and oxygenation of ribulose-1,5-bisphosphate. These reactions require that the active site should be closed by a flexible loop (loop 6) of the large subunit. Rubisco from a red alga, Galdieria partita, has the highest specificity for carboxylation reaction among the Rubiscos hitherto reported. The crystal structure of unactivated Galdieria Rubisco has been determined at 2.6 A resolution. The electron density map reveals that a sulfate binds only to the P1 anion-binding site of the active site and the loop 6 is closed. Galdieria Rubisco has a unique hydrogen bond between the main chain oxygen of Val332 on the loop 6 and the epsilon-amino group of Gln386 of the same large subunit. This interaction is likely to be crucial to understanding for stabilizing the loop 6 in the closed state and to making a higher affinity for anionic ligands.
X-ray structure of Galdieria Rubisco complexed with one sulfate ion per active site.,Okano Y, Mizohata E, Xie Y, Matsumura H, Sugawara H, Inoue T, Yokota A, Kai Y FEBS Lett. 2002 Sep 11;527(1-3):33-6. PMID:12220629
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Okano Y, Mizohata E, Xie Y, Matsumura H, Sugawara H, Inoue T, Yokota A, Kai Y. X-ray structure of Galdieria Rubisco complexed with one sulfate ion per active site. FEBS Lett. 2002 Sep 11;527(1-3):33-6. PMID:12220629