1. Enzymes bind their substrates using ionic, covalent, polar interactions, etc. Polysaccharides could be bound to lysozyme by hydrogen bonding to e.g. aspartate or C=O groups in the peptide backbone.
2. Prosthetic groups, coenzymes and metal ions.
   • ATP in hexokinase - soluble coenzyme provides energy/phosphate for glucose phosphorylation.
   • FeS Riske cluster in ferredoxin - prosthetic group carries electrons.
   • Coenzyme-A in citrate synthase - coenzyme transfers acetyl groups from pyruvate to oxaloacetate.
   • Haem in haemoglobin - prosthetic group carries oxygen.
   • NAD⁺ in alcohol dehydrogenase - coenzyme accepts electrons (H⁻) from alcohol when it is dehydrogenated.
   • Vanadium (III) in nitrogenase - metal ion donates electrons to nitrogen when it is hydrogenated to ammonia.
3. Saturation kinetics means that as a reactant concentration increases, the order of reaction changes from 1^st to 0^th.
4. K_m is (approximately) the dissociation constant for the ES complex, and V_m is the overall ROR (k₃[ES]) when all the enzyme is saturated, i.e. the maximum rate the enzyme can run at. K_m is the substrate concentration that gives V= ½V_m.
5. k_cat = V_m ⁄ [E]_T = 30 × 10⁻³ mol L⁻¹ s⁻¹/ (1 × 10⁻³ g L⁻¹ ⁄ 20,000 g mol⁻¹) = 600,000 s⁻¹. Typical for carbonic anhydrase.
6. Diisopropyl phosphofluoridate (DIPF) is a suicide inhibitor of acetylcholine esterase: it binds irreversibly to AChE, having been activated in the same way as the genuine substrate. It might be useful as a nerve gas or pesticide, depending on its specificity for human or insect AChE.
7. Phosphate is a competitive inhibitor: no effect on V_m (Y-intercept same), but increased K_m (X-intercept lower).
8. PFK is regulated:
   • Because it is an important gatekeeper to glycolysis.
   • Because the reaction it catalyses is essentially irreversible.
   • By feedback allosteric inhibition by ATP and citrate.
   • By feedforward activation by AMP and ADP.
   • By working as a pair with fructose-1,6-bis-phosphatase, which catalyses a similar (but not identical) reverse reaction.
9. Trypsin is secreted as a zymogen to prevent it digesting the cell in which it is synthesised.