Related Experiment Video
Updated: Jun 5, 2026

Measurement of Heme Synthesis Levels in Mammalian Cells
Published on: July 9, 2015
Guanine-rich RNAs and DNAs that bind heme robustly catalyze oxygen transfer reactions
Lester C-H Poon1, Stephen P Methot, William Morabi-Pazooki
1Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
Abstract:
Diverse guanine-rich RNAs and DNAs that fold to form guanine quadruplexes are known to form tight complexes with Fe(III) heme. We show here that a wide variety of such complexes robustly catalyze two-electron oxidations, transferring oxygen from hydrogen peroxide to thioanisole, indole, and styrene substrates. Use of (18)O-labeled hydrogen peroxide reveals the source of the oxygen transferred to form thioanisole sulfoxide and styrene oxide to be the activated ferryl moiety within these systems. Hammett analysis of the kinetics of thioanisole sulfoxide formation is unable to distinguish between a one-step, direct oxygen transfer and a two-step, oxygen rebound mechanism for this catalysis. Oxygen transfer to indole produces a range of products, including indigo and related dyes. Docking of heme onto a high-resolution structure of the G-quadruplex fold of Bcl-2 promoter DNA, which both binds heme and transfers oxygen, suggests a relatively open active site for this class of ribozymes and deoxyribozymes. That heme-dependent catalysis of oxygen transfer is a property of many RNAs and DNAs has ramifications for primordial evolution, enzyme design, cellular oxidative disease, and anticancer therapeutics.
Related Concept Videos
Oxygen Transport in the Blood
Hemoglobin
When all four heme groups are bound to oxygen, the resulting molecule is called oxyhemoglobin. As a result, arterial blood...
Cooperative Binding of Transcription Regulators
Cooperative Binding of Transcription Regulators
Riboswitches
The aptamer has high specificity for a particular metabolite which allows riboswitches to specifically regulate...
Ribozymes
Ribozymes can be...

