2.3 Most enzymes are proteins 2.3. 1 Some enzymes require no other chemical groups other than their amino acid residues for activity. (e.g) 2.3.2 Other enzymes require additional chemical components called prosthetic groups(covalently bound) (or cofactors). 2.3.3 Prosthetic groups could be inorganic metal ions(e.g, Fe2+, Mg2+, Mn2+, Zn2+)or complex organic or metalloorganic molecules called coenzymes 2.3. 4 a complete catalytically active enzyme (including its prosthetic group) is called a holoenzyme 2.3.5 The protein part of an enzyme(without its prosthetic group) is called the apoenzyme.2.3 Most enzymes are proteins. 2.3.1 Some enzymes require no other chemical groups other than their amino acid residues for activity. (e.g.) 2.3.2 Other enzymes require additional chemical components called prosthetic groups (covalently bound) (or cofactors). 2.3.3 Prosthetic groups could be inorganic metal ions (e.g., Fe2+, Mg2+, Mn2+, Zn2+) or complex organic or metalloorganic molecules called coenzymes. 2.3.4 A complete catalytically active enzyme (including its prosthetic group) is called a holoenzyme. 2.3.5 The protein part of an enzyme (without its prosthetic group) is called the apoenzyme