Discovery of a second citric acid cycle complex

Dirk Roosterman; Graeme Stuart Cottrell

doi:10.1016/j.heliyon.2023.e15968

Discovery of a second citric acid cycle complex

Heliyon. 2023 May 12;9(5):e15968. doi: 10.1016/j.heliyon.2023.e15968. eCollection 2023 May.

Authors

Dirk Roosterman¹, Graeme Stuart Cottrell²

Affiliations

¹ Independent Scholar, Germany.
² School of Pharmacy, University of Reading, Reading, RG6 6AP, UK.

Abstract

Together, Nobel Prize honoured work, mathematics, physics and the laws of nature have drawn a concept of clockwise cycling carboxylic acids in Krebs' Citric Acid Cycle. A Citric Acid Cycle complex is defined by specific substrate, product and regulation. Recently, the Citric Acid Cycle 1.1 complex was introduced as an NAD⁺-regulated cycle with the substrate, lactic acid and the product, malic acid. Here, we introduce the concept of the Citric Acid Cycle 2.1 complex as an FAD-regulated cycle with the substrate, malic acid and the products, succinic acid or citric acid. The function of the Citric Acid Cycle 2.1 complex is to balance stress situations within the cell. We propose that the biological function of Citric Acid Cycle 2.1 in muscles is to accelerate recovery of ATP; whereas in white tissue adipocytes our testing of the theoretical concept led to the storage of energy as lipids.

Keywords: Citric acid cycle; Proton-linked monocarboxylate transporter; Pyruvate dehydrogenase complex.

Publication types

Review