meh... if u r referrin to enzymes, specifically, then:
enzymes are biological catalysts, hence wif out them, the metabolic activities in the bodies would be alot slower than what they are now... not sure what you mean by physical nature though... but enzyme has everything to do with any features within the organisms' bodies...
such as, for physical appearance: slow metabolic rate would not allow organisms to have the physical shape they are in now... perhaps some new features would be necessary to compensate and advantageous with the slow metabolic process...
*thinks of a lion with a mouth larger than its body... stomac acid in its mouth so that other animals walkin accidntally into its mouth will be digested right away... XD
