Cofactor Engineering

Cofactor engineering, a subset of metabolic engineering, is defined as the manipulation of the use of cofactors in an organism’s metabolic pathways. In cofactor engineering, the concentrations of cofactors are changed in order to maximize or minimize metabolic fluxes. This type of engineering can be used to optimize the production of a metabolite product or to increase the efficiency of a metabolic network. The use of engineering single celled organisms to create lucrative chemicals from cheap raw materials is growing, and cofactor engineering can play a crucial role in maximizing production. The field has gained more popularity in the past decade and has several practical applications in chemical manufacturing, bioengineering and pharmaceutical industries. Cofactor engineering, a subset of metabolic engineering, is defined as the manipulation of the use of cofactors in an organism’s metabolic pathways. In cofactor engineering, the concentrations of cofactors are changed in order to maximize or minimize metabolic fluxes. This type of engineering can be used to optimize the production of a metabolite product or to increase the efficiency of a metabolic network. The use of engineering single celled organisms to create lucrative chemicals from cheap raw materials is growing, and cofactor engineering can play a crucial role in maximizing production. The field has gained more popularity in the past decade and has several practical applications in chemical manufacturing, bioengineering and pharmaceutical industries. Cofactors are non-protein compounds that bind to proteins and are required for the proteins normal catalytic functionality. Cofactors can be considered “helper molecules” in biological activity, and often affect the functionality of enzymes. Cofactors can be both organic and inorganic compounds. Some examples of inorganic cofactors are iron or magnesium, and some examples of organic cofactors include ATP or coenzyme A. Organic cofactors are more specifically known as coenzymes, and many enzymes require the addition of coenzymes to assume normal catalytic function in a metabolic reaction. The coenzymes bind to the active site of an enzyme to promote catalysis. By engineering cofactors and coenzymes, a naturally occurring metabolic reaction can be manipulated to optimize the output of a metabolic network. Cofactors were discovered by Arthur Harden and William Young in 1906, when they found that the rate of alcoholic fermentation in unboiled yeast extracts increased when boiled yeast extract was added. A few years after, Hans von Euler-Chelpin identified the cofactor in the boiled extract as NAD+. Other cofactors, such as ATP and coenzyme A, were discovered later in the 1900s. The mechanism of cofactor activity was discovered when, Otto Heinrich Warburg determined in 1936 that NAD+ functioned as an electron acceptor. Well after these initial discoveries, scientists began to realize that the manipulation of cofactor concentrations could be used as tools for the improvement of metabolic pathways. An important group of organic cofactors is the family of molecules referred to as vitamins. Vitamin B12 (cobalamin), for example, plays a crucial role in the human body, while coenzyme B12, its derivative, is found in the metabolisms of every type of cell in our bodies. Its presence affects the synthesis and regulation of cellular DNA as well as taking part in fatty acid synthesis and energy production. Cofactors are required by many important metabolic pathways, and it is possible for the concentrations of a single type of cofactor to affect the fluxes of many different pathways . Minerals and metallic ions that organisms uptake through their diet provide prime examples of inorganic cofactors. For instance Zn2+ is needed to assist the enzyme carbonic anhydrase as it converts carbon dioxide and water to bicarbonate and protons. A widely recognized mineral that acts as a cofactor is iron, which is essential for the proper function of hemoglobin, the oxygen transporting protein found in red blood cells. This example in particular highlights the importance of cofactors in animal metabolism. Cofactor engineering is significant in the manipulation of metabolic pathways. A metabolic pathway is a series of chemical reactions that occur in an organism. Metabolic engineering is the subject of altering the fluxes within a metabolic pathway. In metabolic engineering, a metabolic pathway can be directly altered by changing the functionality of the enzymes involved in the pathway. Cofactor engineering, offers a distinct approach, and some advantages, to altering a metabolic pathway. Instead of changing the enzymes used in a pathway, the cofactors can be changed. This may give metabolic engineers an advantage due to certain properties of cofactors and how they can be modified.