Question

What is substrate level phosphorylation and what is its main source of energy?

Answer 1

Substrate-level phosphorylation is a type of metabolic reaction that results in the formation of adenosine triphosphate (ATP) or guanosine triphosphate (GTP) by the direct transfer and donation of a phosphoryl (PO₃) group to adenosine diphosphate (ADP) or guanosine diphosphate (GDP) from a phosphorylated reactive intermediate.

The main source of energy is that the new bond which is build is more stable than the former bond.

It an oxidation takes place before the phophorylation. When an aldehyde is oxidated to an carboxylic acid energy will be released. This energy will be used to phosphylate the carboxylic acid and the resulting anhydride has a high group transfer potential. That means that the anhydride is very reactive and not very stable.