The Enzyme Commission<unk> <unk>  is a<unk> ical classification scheme for enzymes, based on the chemical reactions they catalyze.
As a system of enzyme nomenclature, every<unk>  is associated with a recommended name for the respective enzyme.
Strictly speaking,<unk> s do not specify enzymes, but enzyme-catalyzed reactions. If different enzymes (for instance from different organisms) catalyze the same reaction, then they receive the same<unk> . By contrast, UniProt identifiers uniquely specify a protein by its amino acid sequence.
EC number
Molecular mass
Spin quantum number
Mass versus weight
Extraction ratio
Density
Polarization density
Oxygen permeability