COMPLEX I Meaning and
Definition
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Complex I, also known as NADH:ubiquinone oxidoreductase, is a multi-subunit enzyme complex found in the inner mitochondrial membrane. It plays a crucial role in the electron transport chain as the first and largest enzyme complex involved in the oxidative phosphorylation process.
Complex I is responsible for the initial step of transferring electrons from NADH (Nicotinamide Adenine Dinucleotide) to ubiquinone (coenzyme Q) within the electron transport chain. This transfer of electrons occurs through a series of redox reactions and occurs in several steps. During this process, complex I helps to generate a transmembrane electrochemical gradient, which is utilized to produce adenosine triphosphate (ATP), the cell's main energy currency.
The complex I structure consists of various subunits, with over 40 subunits identified in mammals. These subunits are organized into three functional modules: a membrane arm, a proximal arm, and a connecting arm. The membrane arm spans the mitochondrial inner membrane and contains the electron transfer chains, while the other arms serve as structural supports and participate in the catalytic functions.
Mutations or dysfunctions in complex I can lead to a variety of genetic disorders, including Leigh syndrome and Parkinson's disease, both of which are associated with impaired mitochondrial function. Research into the structure and function of complex I is ongoing, with the aim of understanding its role in health and disease and potentially developing targeted therapies to treat complex I-related disorders.
