In Vitro Reconstitution of Metabolic Pathways: Insights into Nature's Chemical Logic

In vitro analysis of metabolic pathways is becoming a powerful method for gaining a deeper understanding of nature's core biochemical transformations. Through the astounding advances in biotechnology, the purification of the enzymatic components of a given metabolic pathway is becoming a tractable problem; such in vitro studies permit scientists to capture the fine details of the mechanisms, kinetics, and identities of organic products of enzymatic reactions. In this review, we describe eleven metabolic pathways that have been the subject of recently reported in vitro reconstitution studies. In addition, we have selected and analyzed a subset of four case studies within these eleven examples that exemplify the remarkable organic chemistry that occurs within biological systems. These examples serves as tangible reminders that nature's biochemical routes obey the fundamental principles of organic chemistry, as their chemical mechanisms are reminiscent of those occurring in conventional synthetic organic routes. The illustrations of biosynthetic chemistry presented in this review might inspire the development of biomimetic chemistries involving abiotic chemical techniques. 1 Introduction 2 Bacterial Metabolites 2.1 Fatty Acids 2.2 Farnesene 2.3 O-Polysaccharides 3 Plant Metabolites 3.1 Dhurrin 3.2 Camalexin 4 Polyketides and Nonribosomal Peptides 4.1 Aromatic Polyketides 4.1.1 Actinorhodin-Derived Polyketides 4.1.2 Enterocin 4.2 Fungal Polyketides 4.2.1 Norsolorinic Acid 4.2.2 Dihydromonacolin L 4.3 Assembly Line Polyketides and Nonribosomal Peptides 4.3.1 6-Deoxyerythronolide B 4.3.2 Asperlicin 5 Discussion of Chemical Insights 5.1 Allylic Carbocation Chemistry Drives Farnesene Synthesis 5.2 Multifunctional Oxidation Chemistry of Cytochrome P450 Enzymes 5.3 A Remarkable Favorskiiase Enzyme Within Enterocin Biosynthesis 5.4 Diels-Alder Chemistry Appears in Biology 6 Concluding Remarks