Virtuelle (Nano) Welten PDB Molecule of the Month 93: Citrate Synthase

Stop and Go

The citrate synthase enzyme found in many bacteria is larger than ours, as seen in this structure of the enzyme from Escherichia coli (PDB entry 1nxg ). It is composed of six identical subunits, but if you look from the side (as shown in the lower picture), you can see that each pair of subunits has a similar Z shape as our enzyme. The bacterial enzyme has an additional site that binds to NADH, shown here in magenta. Binding of NADH slows the action of the enzyme. This helps the cell regulate its level of energy production: high levels of NADH mean that the cell has plenty of energy, so it doesn't need to break down any more sugar.

Next: Exploring the Structure
Previous: Citrate Synthase