Song: Chymotrypsin (to the tune of “eight days a week,” by the beatles)*

The enzyme chymotrypsin, it binds a peptide tight. A P1 aromatic side chain, fits the S1 site. Ohhh, bind it, cleave it; bind it, cleave it. The extended peptide binds as, a beta sheet. Asp polarizes His which plucks a proton from Ser. The activated nucleophile, attacks a carbonyl that's near. Ohhh, bind it, cleave it; bind it; cleave it. The catalytic triad: it can't be beat. Approximation, holding substrates right. Acid, base, covalent, catalysis that's out-a-s ight. The tetrahedral intermediate, in the oxyanion hole. Collapses to the acyl-enzyme, halfway to the goal. Ohhh, bind it, cleave it; bind it, cleave it. Deacylation by water, and it's complete. Approximation, holding substrates right. Acid, base, covalent, catalysis that's out-a-s ight. The zymogen's activated by a cut before Ile-16-ee Tertiary contortions, more impressive than Houdini Ohhh, bind it, cleave it; bind it, cleave it. This pancreatic protease, it helps us eat … it helps us eat.