Self-sufficient heterogeneous biocatalysis systems based on NAD(P) recycling: new perspectives on construction

Nicotinamide adenine dinucleotide (phosphoric acid) (NAD(P)) dependent oxidoreductases are an important class of enzymes because they can catalyze a broad range of synthetic transformations. The co-immobilization of oxidoreductases, NAD(P), and NAD(P) regeneration catalysts can form a self-sufficient heterogeneous system (SSHBS) with improved stability, recyclability, and excellent NAD(P) recycling, thus significantly increasing the possibility of the enzymatic reactions in industrial applications. However, due to the complexity of SSHBSs, there are many factors that need to be considered to satisfy the requirements of practical manufacturing by the enzymatic systems. Therefore, in this review, the construction of SSHBSs is discussed from the viewpoint of potential scale-up applications of biocatalysis systems. First, the NAD(P) regeneration part, as an "energy supplement" of SSHBSs, is illustrated from the perspective of the economic effects arising from cofactor regeneration efficiency. This is followed by the cost consideration in the preparation of whole SSHBSs. Then, the flexibility of NAD(P), the key hub of SSHBSs, which is distinctly affected by immobilization approach, is highlighted based on the advanced examples of SSHBSs to exhibit its significant effect on the whole efficiency of an SSHBS. Finally, a perspective on how this research field will evolve in facing the existing challenges is provided.