This book is the second of two volumes that deal with discovery of chemical pathways of biosynthesis of natural products (secondary metabolites). The first volume covered the use of isotopes in biosynthetic research and the formation of enzyme cofactors and reduced polyketides. This second volume describes biosynthesis of aromatic (unreduced) polyketides, enzymes responsible for cyclization of terpenoids (isoprenoids), and biochemical generation of selected classes of alkaloids (prenylated tryptophan, tropane, pyrrolizidine). Knowledge of the pathways and the techniques to elucidate them opens the door to combinatorial biosynthesis as well as to the production of targeted pharmaceutical agents utilizing a combination of chemistry, molecular biology and protein biochemistry.