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Related Concept Videos

Preparation and Reactions of Thiols02:33

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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Phase II Reactions: Glutathione Conjugation and Mercapturic Acid Formation01:22

Phase II Reactions: Glutathione Conjugation and Mercapturic Acid Formation

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Glutathione, a tripeptide made up of glutamate, cysteine, and glycine, is a critical player in the detoxification of drugs and xenobiotics via a process known as glutathione conjugation or mercapturic acid formation. This phase II biotransformation reaction involves the covalent binding of glutathione to a drug or its metabolite, enhancing the compound's water solubility and enabling its excretion.
Several distinctive characteristics distinguish glutathione conjugation from other phase II...
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Preparation and Reactions of Sulfides02:26

Preparation and Reactions of Sulfides

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Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
4.3K
Phase II Reactions: Sulfation and Conjugation with α-Amino Acids01:19

Phase II Reactions: Sulfation and Conjugation with α-Amino Acids

1.4K
Sulfation and α-amino acid conjugation are two critical biotransformation reactions in drug metabolism. Sulfation, a phase II biotransformation reaction, involves adding a polar sulfate group to a drug, enhancing its water solubility and promoting excretion. This process can either co-occur with or occur independently of glucuronidation. Nonmicrosomal sulfotransferase enzymes catalyze the process. The reaction involves 3'-phosphoadenosine-5'-phosphosulfate or PAPS coenzyme...
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EDTA: Auxiliary Complexing Reagents01:26

EDTA: Auxiliary Complexing Reagents

1.6K
EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...
1.6K
Phase II Conjugation Reactions: Overview01:14

Phase II Conjugation Reactions: Overview

1.3K
Conjugation, a key component of phase II biotransformation reactions, is a vital process in drug detoxification. It involves transferring endogenous substances like glucuronic acid, sulfate, and glycine to drugs or their metabolites formed in phase I reactions. These conjugation reactions, often catalyzed by specific enzymes, transform potentially harmful metabolites into inactive, water-soluble forms easily excreted in urine or bile. By enhancing polarity and eliminating pharmacological...
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Related Experiment Video

Updated: May 3, 2026

Synthesis and Bioconjugation of Thiol-Reactive Reagents for the Creation of Site-Selectively Modified Immunoconjugates
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A new reagent for stable thiol-specific conjugation.

George Badescu1, Penny Bryant, Julia Swierkosz

  • 1PolyTherics Ltd, The London Bioscience Innovation Centre , 2 Royal College Street, London NW1 0NH, U.K.

Bioconjugate Chemistry
|February 12, 2014
PubMed
Summary
This summary is machine-generated.

A new reagent, PEG-mono-sulfone 3, offers improved stability for protein therapeutics. This monothiol-selective conjugation method prevents undesirable exchange reactions, enhancing therapeutic efficacy and drug delivery.

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Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry
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Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

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Area of Science:

  • Bioconjugation Chemistry
  • Protein Therapeutics
  • Drug Delivery Systems

Background:

  • Protein therapeutics often require modification to enhance efficacy.
  • Poly(ethylene glycol) (PEG) conjugation is a common strategy.
  • Existing maleimide reagents for PEGylation can lead to unstable conjugates due to exchange reactions.

Purpose of the Study:

  • To develop a novel, stable monothiol-selective conjugation reagent.
  • To overcome the limitations of maleimide-based reagents in protein modification.
  • To improve the stability and efficacy of protein therapeutics.

Main Methods:

  • Development of PEG-mono-sulfone 3, a latently reactive, monothiol-selective conjugation reagent.
  • Comparative conjugation efficiency studies with PEG-maleimide and other thiol-selective reagents (vinyl sulfone, acrylate, halo-acetamides).
  • Stability assessment of PEG-mono-sulfone 3 conjugates versus PEG-maleimide conjugates.

Main Results:

  • PEG-mono-sulfone 3 demonstrated more efficient conjugation under mild conditions compared to other reagents.
  • The latent reactivity of PEG-mono-sulfone 3 allows for tailored conjugation and subsequent stabilization via ketone reduction.
  • Comparative stability studies showed PEG-mono-sulfone 3 conjugates were significantly more stable against deconjugation than PEG-maleimide conjugates.

Conclusions:

  • PEG-mono-sulfone 3 is a superior reagent for monothiol-selective PEGylation, offering enhanced stability.
  • This novel reagent addresses the lability issues associated with maleimide-based conjugates.
  • The developed method holds promise for improving the pharmacokinetic profiles and therapeutic outcomes of protein-based drugs.