ATP synthase

ATP synthase (EC 3.6.3.14) is an important enzyme that creates the energy storage molecule adenosine triphosphate (ATP). ATP is the most commonly used "energy currency" of cells from most organisms. It is formed from adenosine diphosphate (ADP) and inorganic phosphate (P_i), and needs energy for its formation.

The overall reaction sequence is: ADP + P_i + Energy → ATP, where ADP and P_i are joined together by ATP synthase

Energy used is available in the form of hydrogen ions (H+
), moving down an electrochemical gradient, such as from the thylakoid lumen through the thylakoid membrane and into the chloroplast stroma (of plants) or from the inter-membrane space and into the matrix in mitochondria.

Structure

Located within the thylakoid membrane and the inner mitochondrial membrane, ATP synthase consists of two regions

the F₁ portion of the ATP synthase is outside the membrane, but inside the matrix of the mitochondria.

Mitochondria structure: (1) inner membrane, (2) outer membrane, (3) cristae, (4) matrix