Gram-positive type citrate synthase in the thermophilic green gliding bacterium Chloroflexus aurantiacus

Abstract

Some properties of the citrate synthase from Chloroflexus aurantiacus have been examined in crude cell‐free extracts and partially purified preparations. The enzyme had an approximate native molecular size of 140 000, was not inhibited by NADH or 2‐oxoglutarate but was inhibited by ATP (about 50% at 5 mM). The Km for acetyl CoA at pH 8.2 in the presence of 0.5 mM oxaloacetate was determined to be 25 μM. These properties are characteristic of the ‘small’ size class of citrate synthases normally associated with gram‐positive eubacteria, despite the fact that Chloroflexus stains gram‐negatively.

Mutagenesis, cloning and complementation analysis of C4‐dicarboxylate transport genes from Rhodobacter capsulatus

“…Cell-free extracts were prepared from 250ml cultures grown aerobically in the dark on RCV-pyruvate n'ledium by resuspension in 1 ml 50mM Tris-HCI buffer (pH 8.0) followed by sonicalion and microfugation (10 min) to remove debris. Citrate synthase and malate dehydrogenase were assayed according to Kelly (1988), aconilase and fumarase at 240nm according to Reeves ef al. (1971), isocitrate dehydrogenase according to Leyland et al (1989), and succinate dehydrogenase according to Morgan ef aA (1986).…”

Induction of carbon monoxide dehydrogenase to facilitate redox balancing in a ribulose bisphosphate carboxylase/oxygenase-deficient mutant strain of Rhodospirillum rubrum

“…PEP carboxytransphosphorylase was assayed according to Wood et al (1969). The enzymes of the oxidative tricarboxylic cycle were assayed under oxic conditions by standard methods, with malate dehydrogenase (Kelly 1988), isocitrate dehydrogenase (Leyland and Kelly 1989), pyruvate dehydrogenase (Willison 1988), citrate synthase (Willison 1988), and pyruvate kinase (Schedel et al 1975) as markers of this pathway.…”