Residue-specific Protein Labeling
Residue-specific Protein Labeling - Related Videos
03:27
Labeling of Surface-Accessible Cysteine Residues in Engineered Virus-Like Particles
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2026
Source: Natilla, A.,and Hammond, R. W. Analysis of the Solvent Accessibility of Cysteine Residues on Maize rayado fino virus Virus-like Particles Produced in Nicotiana benthamiana Plants and Cross-linking of Peptides to VLPs. J. Vis. Exp. (2013)This video demonstrates site-specific fluorescent labeling of mutant virus-like particles (VLPs) produced in Nicotiana benthamiana using a thiol-reactive dye, followed by purification and gel electrophoresis to confirm surface modification.
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Residue-specific Incorporation of Noncanonical Amino Acids into Model Proteins Using an Escherichia coli Cell-free Transcription-translation System
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Cited by 16 •
2016
An easy-to-use, cell-free expression protocol for the residue-specific incorporation of noncanonical amino acid analogs into proteins, including downstream analysis, is presented for medical, pharmaceutic, structural and functional studies.
07:08
Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues
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Cited by 1 •
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Synthetic protein sequences based on consensus motifs typically ignore co-evolving residues, that imply interpositional dependencies (IPDs). IPDs can be essential to activity, and designs that disregard them may result in suboptimal results. This protocol uses StickWRLD to identify IPDs and help inform rational protein design, resulting in more efficient results.
12:07
Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues
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Cited by 23 •
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DNA and proteins are sequence-specifically labeled with affinity or fluorescent reporter groups using DNA or protein methyltransferases and synthetic cofactor analogues. Depending on the cofactor specificity of the enzymes, aziridine or double activated cofactor analogues are employed for one- or two-step labeling.
06:48
Antibody Labeling with Fluorescent Dyes Using Magnetic Protein A and Protein G Beads
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Cited by 3 •
2016
The on-bead method for labeling antibodies with small molecules enables labeling of a small amount of antibodies directly from cell media. This method is compatible with amine and thiol chemistry, and can handle multiple samples in parallel, manually or using automated platforms.
FAQs
Reaction selectivity depends on chemical features of the targeted side chain, including its nucleophilicity, which is its tendency to participate in chemical reactions, and its accessibility within the protein. A selective reagent or enzyme can therefore favor particular residue types rather than reacting uniformly with every amino acid. These properties help determine which protein molecules receive the label and how consistently labeling occurs.
This strategy targets a class of amino acid residues rather than a predetermined location in the primary sequence. As a result, it does not require a unique sequence position for recognition. The labeled sites reflect where the relevant residue types and side-chain environments occur, making the approach useful for examining proteins when site-specific sequence targeting is not required.
A residue’s chemical reactivity alone does not determine whether it will be labeled; its accessibility within the folded protein also influences recognition by the reagent or enzyme. Controlled reaction conditions help regulate the interaction between the labeling system and the protein. Consequently, labeling patterns can provide information about molecular structure or conformational changes when conditions are carefully managed.
A typical workflow begins by selecting a chemical reagent or enzyme with the desired residue preference and combining it with the protein under controlled reaction conditions. After labeling, the modified protein can be examined using an appropriate detection or analytical method. Depending on the label and study objective, researchers may track, detect, purify, or characterize the protein.
The attached chemical group may be detectable, functional, or both, depending on the experimental goal. Fluorescence can support visualization or tracking, while mass spectrometry can help analyze the labeled protein and its modification. Other analytical methods may also be selected, allowing the same labeling strategy to support detection, purification, or molecular characterization.
In biological research, labeled proteins can be used to examine structure, conformational changes, interactions, localization, and molecular dynamics. The resulting signal or analytical signature connects the modified protein to one of these properties without requiring a unique sequence position. The approach also supports assay development and bioconjugation, extending its use beyond basic protein characterization.