STM Article Repository

Landino, Lisa and Boike, Lydia and Lain, Taylor (2024) Inhibition of Lactate Dehydrogenase-A by Singlet Oxygen and Hypochlorous Acid via Cysteine Oxidation and Irreversible Conformational Changes. BioChem, 4 (1). pp. 18-37. ISSN 2673-6411

[thumbnail of biochem-04-00002.pdf] Text
biochem-04-00002.pdf - Published Version

Download (2MB)
[thumbnail of biochem-04-00002.pdf] Text
biochem-04-00002.pdf - Published Version

Download (2MB)

Abstract

Muscle lactate dehydrogenase (LDH-A) catalyzes the reduction of pyruvate to lactate, the end product of anaerobic glycolysis. LDH-A is overexpressed in many cancers prior to and even when tumors receive adequate oxygen, and lactate has multiple cellular roles. We assessed the effect of singlet oxygen and hypochlorous acid (HOCl) on mammalian LDH-A. Oxidants induced distinct patterns of protein crosslinks observed by SDS-PAGE under reducing conditions. LDH-A cysteines were detected using fluorescein-modified maleimide to assess their oxidation and accessibility. Singlet oxygen initially increased cysteine exposure, but higher doses resulted in their oxidation in addition to non-reducible covalent crosslinks. LDH-A cysteines were oxidized by micromolar HOCl (1–10 equivalents over enzyme) but were resistant to millimolar H2O2, chloramines and Angeli’s salt. HOCl oxidation inhibited LDH-A activity and yielded inter-chain disulfides observed by nonreducing SDS-PAGE. Disulfide reduction did not restore LDH-A activity that was lost due to HOCl oxidation. An irreversible conformational change induced by HOCl was detected by native gel electrophoresis and tryptophan fluorescence. In the absence of pyruvate, LDH-A enhanced NADH oxidation resulting in H2O2 formation. Singlet oxygen, but not HOCl, initiated this superoxide-dependent chain reaction. Once damaged by both singlet oxygen or HOCl, LDH-A had decreased NADH oxidation activity.

Item Type: Article
Subjects: GO for ARCHIVE > Multidisciplinary
Depositing User: Unnamed user with email support@goforarchive.com
Date Deposited: 05 Feb 2024 06:11
Last Modified: 05 Feb 2024 06:11
URI: http://eprints.go4mailburst.com/id/eprint/2124

Actions (login required)

View Item
View Item