Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies "crystal-kingdom" chemical substances chemical compounds Class amides [RkE(=O)l(OH)m (l≠0; ≥1 (OH):=(NR2))] Class peptides [H2NCH(R)C(=O)[NHCH(R)C(=O)]nOH] Class polypeptides Class proteins Class globular proteins "enzymes" 2,3-bisphosphoglycerate phosphatase acetylcholinesterase aconitase adenylate cyclase aldolase amylase β-galactosidase bisphosphoglycerate mutase carbonic anhydrase carboxypeptidase chymotrypsin citrate synthase dehydrogenases formic hydrogenlyase fumarase galactose 1-phosphate uridyl transferase kinases lipase nitrogenase pepsin phosphoglucomutase phosphoglucose isomerase phosphoglyceromutase rennin ribulose bisphosphate carboxylase salivary amylase succinyl CoA synthetase triose phosphate isomerase trypsin UDP-galactose-4-epimerase