sentences:  These carbons are electrophiles that readily form covalent bonds by acting as acceptors in Michael reactions to form covalent bonds with exposed nucleophile sites, particularly thiol residues, in diverse proteins.The reaction inactivates or reduces the activity of various functionally important target proteins and is one mechanism by which cylopentenone PGs influence cell function.All of the reactions undergone by the above cited PGs occur spontaneously (i.e.