Enzymes as Parts in Need of Replacement – and How to Extend Their Working Life

Nathan D. Tivendale, Andrew D. Hanson, Christopher S. Henry, Adrian D. Hegeman, A. Harvey Millar

Research output: Contribution to journalReview articlepeer-review

2 Scopus citations


Enzymes catalyze reactions in vivo at different rates and each enzyme molecule has a lifetime limit before it is degraded and replaced to enable catalysis to continue. Considering these rates together as a unitless ratio of catalytic cycles until replacement (CCR) provides a new quantitative tool to assess the replacement schedule of and energy investment into enzymes as they relate to function. Here, we outline the challenges of determining CCRs and new approaches to overcome them and then assess the CCRs of selected enzymes in bacteria and plants to reveal a range of seven orders of magnitude for this ratio. Modifying CCRs in plants holds promise to lower cellular costs, to tailor enzymes for particular environments, and to breed enzyme improvements for crop productivity.

Original languageEnglish (US)
Pages (from-to)661-669
Number of pages9
JournalTrends in Plant Science
Issue number7
StatePublished - Jul 2020

Bibliographical note

Funding Information:
N.D.T. and A.H.M. were supported by the Australian Research Council ( CE140100008 ; DP180104136 ). A.D. Hanson and C.S.H. gratefully acknowledge support from US National Science Foundation grant IOS-1444202 . C.S.H. also acknowledges support from the US Department of Energy , Office of Biological and Environmental Research under contract DE-AC02-06CH11357 . A.D. Hegeman gratefully acknowledges support from US National Science Foundation grant IOS-1238812 .


  • catalytic rate
  • metabolic flux
  • protein turnover
  • stable isotope labeling
  • synthetic biology

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

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