Reaction coupling in ADH1A alcohol dehydrogenase enzyme by exciplex formation with adenosine diphosphate moderated by low-energy electronic excited states

Igor Khmelinskii and Vladimir I. Makarov
Phys. Rev. E 103, 052405 – Published 10 May 2021

Abstract

Two commonly accepted theories about enzymes were revisited. The first states that adenosine triphosphate (ATP)–stored energy is only released when the substrate is in place, because the substrate changes the enzyme structure when it is bound to the enzyme. In fact, as demonstrated and discussed presently, no structural changes are required, and ATP-stored energy is released when it can be used. The second states that ATP-released energy moves along the enzyme molecule in the form of molecular vibrations (Davydov's vibrational solitons). In fact, as reported presently, energy released upon ATP hydrolysis moves in the form of excited-state electrons (excitons), with no molecular vibrations involved. The relevant experimental evidence was obtained for the human ADH1A alcohol dehydrogenase enzyme. Spontaneous ATP hydrolysis in the absence of substrate was apparently prevented by electronically excited enzyme + adenosine diphosphate (ADP) + inorganic phosphate (P) complex (exciplex) formed upon ATP hydrolysis. This exciplex kept ADP + P bound and in place for the inverse reaction, until the excess energy was dissipated in the enzyme-catalyzed reaction or by energy transfer to a suitable acceptor. Additionally, and contrary to textbooks, ADH1A has required ATP, working orders of magnitude faster in its presence.

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  • Received 15 January 2021
  • Revised 7 April 2021
  • Accepted 16 April 2021

DOI:https://doi.org/10.1103/PhysRevE.103.052405

©2021 American Physical Society

Physics Subject Headings (PhySH)

Physics of Living Systems

Authors & Affiliations

Igor Khmelinskii1,* and Vladimir I. Makarov2

  • 1Universidade do Algarve, FCT, DQB, and CEOT, 8005-139 Faro, Portugal
  • 2University of Puerto Rico, Rio Piedras Campus, PO Box 23343, San Juan, Puerto Rico 00931-3343, USA

  • *Corresponding author: ikhmelin@ualg.pt

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Vol. 103, Iss. 5 — May 2021

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