Related Experiment Video
Updated: May 1, 2026
09:27
Functional Complementation Analysis FCA: A Laboratory Exercise Designed and Implemented to Supplement the Teaching of Biochemical Pathways
Published on: June 24, 2016
17.3K
Dph7 catalyzes a previously unknown demethylation step in diphthamide biosynthesis.
Zhewang Lin1, Xiaoyang Su, Wei Chen
1Department of Chemistry and Chemical Biology and ‡Proteomics and Mass Spectrometry Core Facility, Cornell University , Ithaca, New York 14853, United States.
Journal of the American Chemical Society
|April 18, 2014
Summary
Diphthamide biosynthesis involves Dph7, an enzyme that modifies an intermediate. This research clarifies Dph7
Area of Science:
- Molecular Biology
- Protein Post-Translational Modifications
Background:
- Diphthamide is a unique post-translational modification on translation elongation factor 2 in archaea and eukaryotes.
- Its biosynthesis involves seven proteins (Dph1-7), with Dph1-5 functions established, and Dph6 identified as the diphthamide synthetase.
- The precise role of Dph7 in the final amidation step remained unclear.
Purpose of the Study:
- To elucidate the molecular function of Dph7 in the diphthamide biosynthesis pathway.
- To revise the established pathway for diphthamide synthesis.
Main Methods:
- Enzymatic assays to characterize Dph7 activity.
- Analysis of reaction intermediates in the diphthamide pathway.
- Biochemical characterization of Dph7 as a methylesterase.
Main Results:
- Dph7 catalyzes a novel step in diphthamide biosynthesis, occurring between Dph5 and Dph6.
- Dph5 produces methylated diphthine, a previously unrecognized intermediate.
- Dph7 functions as a methylesterase, hydrolyzing methylated diphthine to diphthine, enabling subsequent amidation by Dph6.
Conclusions:
- Dph7 is a critical enzyme, acting as a methylesterase in diphthamide biosynthesis.
- The study reveals a revised, more complete pathway for diphthamide synthesis.
- This work clarifies the long-standing question regarding Dph7's molecular role.
Related Concept Videos
01:17Phase II Reactions: Methylation Reactions
915
Methylation is a phase II biotransformation process involving the attachment of a methyl group to a substrate. Enzymes known as methyltransferases orchestrate this reaction.
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
915
01:28Biosynthesis of Nucleic Acids
1.7K
Nucleic acid biosynthesis is a fundamental biochemical process that produces the purine and pyrimidine nucleotides essential for DNA and RNA synthesis. This pathway maintains a balanced nucleotide pool, preventing imbalances that could jeopardize genetic integrity and cellular function. Given the crucial role of nucleotides, their synthesis is tightly regulated to ensure proper cellular homeostasis.Purine BiosynthesisThe biosynthesis of purine nucleotides begins with ribose-5-phosphate, a...
1.7K
01:33Carboxylic Acids to Methylesters: Alkylation using Diazomethane
2.3K
Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.
2.3K
01:57Preparation of Diols and Pinacol Rearrangement
3.2K
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
3.2K
01:26Biosynthesis of Polysaccharides
984
Polysaccharides such as glycogen and starch are synthesized from nucleoside diphosphate sugars, primarily uridine diphosphate glucose (UDPG) and adenosine diphosphate glucose (ADPG). These activated glucose donors act as key intermediates in carbohydrate metabolism and biosynthesis. UDPG primarily involves glycogen synthesis in animals and many bacteria, while ADPG plays a fundamental role in starch synthesis in plants and certain bacteria.UDPG is formed when glucose-1-phosphate reacts with...
984
01:17Drug Metabolism: Phase I Reactions
5.1K
A phase I reaction is a biochemical process that introduces a functionally reactive polar group to a substance. This transformation predominantly occurs in the liver, facilitated by the cytochrome P450 system of hemoproteins situated in the lipophilic endoplasmic reticulum of cells. The metabolite generated through this process can have varying polarities. If it is sufficiently polar, it can be easily excreted in the urine due to its water compatibility. However, if the metabolite is nonpolar,...
5.1K