What is Phosphorylation?
Phosphorylation is one of the most common post-translational modifications of proteins. It is the process of adding a phosphate group (-PO4) to proteins or other molecules. This operation can change the properties and functions of proteins in a short period of time. After phosphorylation, proteins are transformed into substances that regulate key processes such as cell growth, division, and metabolism. The phosphorylation process is reversible. Protein phosphorylation is a process catalyzed by protein kinase (PK) to transfer the phosphate group at the γ position of ATP or GTP to the amino acid residue of the substrate protein. Its reversal process is catalyzed by protein phosphatase (PPase), which is called protein dephosphorylation (dephosphorylation).
What is Oxidative Phosphorylation?
In the biological oxidation process, substrate dehydrogenation produces NADH and FMNH2. While oxidizing and generating water through the respiratory chain, the free energy released is used to couple ADP phosphorylation to generate ATP. This coupling of oxidation and phosphorylation is called oxidative phosphorylation.
The oxidative phosphorylation coupling site is the site where ATP is generated. The P/O ratio refers to the number of moles of inorganic phosphorus consumed for every 1 mole of oxygen atoms consumed when a substance is oxidized, that is, the number of moles of ATP generated.
What is Substrate Level Phosphorylation?
The energy inside the substrate molecule is redistributed during the oxidation process to form high-energy metabolic intermediates, and the energy is concentrated to produce high-energy bonds, which promotes the phosphorylation of ADP to generate ATP. The energy for substrate phosphorylation to form high-energy phosphate compounds comes from the redistribution of energy inside the molecule accompanying substrate dehydrogenation. For example: ATP is produced during glycolysis.
