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Preparation and Reactions of Thiols

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Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.

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Related Experiment Video

Updated: Jul 9, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives

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Published on: February 15, 2016

A conserved mechanism for sulfonucleotide reduction.

Kate S Carroll¹, Hong Gao, Huiyi Chen

¹Department of Chemistry, University of California, Berkeley, California, USA.

|July 13, 2005

Summary

Sulfonucleotide reductases convert activated sulfate to sulfite, essential for biomolecule production in bacteria and plants. This study elucidates the two-step mechanism of APS reductase from Mycobacterium tuberculosis.

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Area of Science:

Biochemistry
Enzymology
Sulfur Metabolism

Background:

Sulfonucleotide reductases are key enzymes in reductive sulfur assimilation, converting activated sulfate (APS or PAPS) to sulfite.
Sulfite is crucial for synthesizing essential biomolecules like cysteine and coenzyme A in bacteria and plants.
Humans lack this pathway, making sulfonucleotide reductases potential therapeutic targets.

Purpose of the Study:

To investigate the reaction mechanism of APS reductase from Mycobacterium tuberculosis.
To understand the role of thioredoxin in the sulfonucleotide reduction process.

Main Methods:

Utilized mass spectrometry.
Employed biochemical approaches.

Main Results:

Supported a two-step reaction mechanism for sulfonucleotide reduction.
Identified an enzyme-thiosulfonate intermediate (E-Cys-S-SO(3-)).
Demonstrated thioredoxin-dependent sulfite release.

Conclusions:

The APS reductase from Mycobacterium tuberculosis follows a two-step mechanism involving an enzyme-thiosulfonate intermediate.
This mechanism is likely conserved across diverse sulfonucleotide reductases, suggesting a common evolutionary origin.