Enzyme by Ciro Santilli 34 Updated +Created
A protein that is a catalyst for some chemical reaction.
For an initial concrete example, consider e. Coli K-12 MG1655 gene thrA.
Video 1.
How Enzymes Work by RCSBProteinDataBank (2017)
Source. Shows in detail how aconitase catalyses the citrate to isocitrate reaction in the citric acid cycle.