cisaconitaattivaihe

Cisaconitaattivaihe, often referred to as cis-aconitate, is a crucial intermediate compound in the citric acid cycle, also known as the Krebs cycle or TCA cycle. This metabolic pathway is central to cellular respiration in aerobic organisms, responsible for generating energy in the form of ATP. Cis-aconitate is formed from citrate, an initial product of the cycle, through an enzymatic reaction catalyzed by the enzyme aconitase. This enzyme facilitates the isomerization of citrate, a tertiary alcohol, into isocitrate, a secondary alcohol. The reaction involves the removal of a molecule of water from citrate, forming an unstable intermediate called *cis*-aconitate, which then rehydrates to form isocitrate. This seemingly simple step is vital because the subsequent oxidation of isocitrate yields the first molecule of carbon dioxide released in the cycle and produces NADH, a high-energy electron carrier essential for ATP synthesis. The position of the double bond in *cis*-aconitate is key to the overall rearrangement of the citrate molecule. Aconitase itself is an iron-sulfur cluster protein that plays a significant role in both the forward and reverse reactions of this isomerization. The presence and efficient functioning of cis-aconitate within the citric acid cycle are therefore fundamental for energy production in most living cells.