The number of catalytic cycles in an enzyme’s lifetime and why it matters to metabolic engineering
Andrew D. Hanson, Donald R. McCarty, Christopher S. Henry, Xiaochen Xian, Jaya Joshi, Jenelle A. Patterson, Jorge D. García-García, Scott D. Fleischmann, Nathan D. Tivendale, A. Harvey Millar
Abstract
Significance The continuous replacement of enzymes and other proteins appropriates up to half the maintenance energy budget in microorganisms and plants. High enzyme replacement rates therefore cut the productivity of biosystems ranging from microbial fermentations to crops. However, yardsticks to assess what drives enzyme protein replacement and guidelines on how to reduce it are lacking. Accordingly, we compared enzymes’ life spans across kingdoms using a new yardstick (catalytic cycles until replacement [CCR]) and related CCR to enzyme reaction chemistry. We concluded that 1) many enzymes fail due to collateral damage from the reaction they catalyze, and 2) such damage and its attendant enzyme replacement costs are mitigable by engineering and are therefore promising targets for synthetic biology.