Related Experiment Video

Updated: Aug 16, 2026

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes
09:54

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Published on: September 12, 2018

Laccase-catalysed iodide oxidation in presence of methyl syringate

Juozas Kulys1, Irina Bratkovskaja, Regina Vidziunaite

  • 1Department of Enzyme Chemistry, Institute of Biochemistry, Mokslininku 12, LT-08662 Vilnius, Lithuania. jkulys@bchi.lt

Biotechnology and Bioengineering
|August 5, 2005
PubMed

Insights

Fungal laccases catalyze potassium triiodide (KI(3)) formation using methyl syringate (MS) as a mediator. Reaction rates vary with laccase type and pH, influenced by redox potential and reversible reaction steps.

Area of Science:

  • Biocatalysis
  • Enzyme kinetics
  • Environmental chemistry

Background:

  • Fungal laccases are versatile oxidoreductases with potential applications in various industrial processes.
  • Understanding the kinetics of laccase-mediated reactions is crucial for optimizing their use.
  • Potassium triiodide (KI(3)) formation is a relevant reaction pathway involving iodide oxidation.

Purpose of the Study:

  • To investigate the kinetics of potassium triiodide (KI(3)) formation catalyzed by fungal laccases.
  • To elucidate the reaction mechanism involving methyl syringate (MS) as a mediator.
  • To compare the activity and kinetic parameters of different recombinant fungal laccase forms.

Main Methods:

  • Utilized recombinant fungal laccase forms: Polyporus pinsitus (rPpL), Myceliophthora thermophila (rMtL), Coprinus cinereus (rCcL), and Rhizoctonia solani (rRsL).
  • Measured triiodide formation rates spectrophotometrically under varying pH conditions (4.5-6.5) and substrate concentrations.
  • Analyzed kinetic data to determine reaction rates, turnover numbers, and reversibility of the catalytic cycle.

Main Results:

  • Triiodide formation rates varied significantly among laccases, with rPpL, rCcL, and rRsL showing higher rates than rMtL at pH 5.5.
  • The reaction rate increased as pH decreased from 6.5 to 4.5.
  • A reaction mechanism was proposed involving methyl syringate oxidation and subsequent reaction with iodide, with reversibility influenced by the laccase's redox potential.

Conclusions:

  • Fungal laccases, particularly rPpL, rCcL, and rRsL, efficiently catalyze KI(3) formation with MS as a mediator.
  • pH significantly impacts the reaction rate, with optimal activity observed at lower pH values.
  • The reversibility of the laccase-mediator interaction plays a key role in the observed kinetic differences and saturation rates.

More Related Videos

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography10:14

Synthesis and Purification of Iodoaziridines Involving Quantitative Selection of the Optimal Stationary Phase for Chromatography

Published on: May 16, 2014

Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities09:10

Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities

Published on: May 27, 2015

Related Concept Videos

Preparation and Reactions of Sulfides02:26

Preparation and Reactions of Sulfides

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.
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene01:13

Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene

Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.
Preparation and Reactions of Thiols02:33

Preparation and Reactions of Thiols

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.
Redox Titration: Iodimetry and Iodometry01:23

Redox Titration: Iodimetry and Iodometry

Iodometry and iodimetry are analytical methods used to determine the concentration of oxidizing or reducing agents using iodine. In iodometric titrations, the oxidizing analyte solution is usually acidified and treated with an excess of iodide ions, which generates an equivalent amount of iodine in equilibrium with triiodide. The released iodine is subsequently titrated directly against a standardized reducing agent. As the dilute iodine color becomes pale yellow, a few drops of freshly...
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide02:44

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation01:22

Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation

Baeyer–Villiger oxidation converts aldehydes to carboxylic acids and ketones to esters. The reaction uses peroxy acids or peracids and is often catalyzed by acid. The reaction is named after its pioneers, Adolf von Baeyer and Victor Villiger. The reaction is achieved by a wide range of peracids such as m-chloroperoxybenzoic acid (mCPBA), perbenzoic acid (C6H5COOOH), peracetic acid (CH3COOOH), hydrogen peroxide (H2O2), and tert-butyl hydroperoxide (t-BuOOH).
The carbonyl center is activated by...