1. Enzymes: structure, origin, classification

1.1 Structure – coenzymes

Enzymes are proteins and, as such, their structure can be described in four stages:

• primary structure: this is the sequence of L-series amino acids, linked together by an amide bond, the peptide bond. This first level of structure is at least indirectly responsible for the higher levels of organization and thus for all protein properties, in particular the catalytic properties of enzymes, but also for the formation of other covalent bonds (post-translational modifications);

• secondary structure: this results from the establishment of hydrogen bonds between the amide (-NH) and carbonyl (-CO) groups of the peptide backbone. The existence of secondary structures stems from the fact...