Thiol-specific Biotinylation
Thiol-specific Biotinylation - Related Videos
09:13
Cell-surface Biotinylation Assay
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2023
A cell can regulate the amount of particular proteins on its cell membrane through endocytosis, following which cell surface proteins are effectively sequestered in the cytoplasm. Once within a cell, these surface proteins can be either destroyed or “recycled” back to the membrane. The cell surface biotinylation assay provides researchers with a way to study these phenomena. The technique makes use of a derivative of the small molecule biotin, which can label surface proteins and then be...
11:25
Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins
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Cited by 1 •
2017
Biochemical and structural analyses of glycosylated proteins require relatively large amounts of homogeneous samples. Here, we present an efficient chemical method for site-specific glycosylation of recombinant proteins purified from bacteria by targeting reactive Cys thiols.
06:18
Brain Slice Biotinylation: An Ex Vivo Approach to Measure Region-specific Plasma Membrane Protein Trafficking in Adult Neurons
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Cited by 28 •
2014
Neuronal membrane trafficking dynamically controls plasma membrane protein availability and significantly impacts neurotransmission. To date, it has been challenging to measure neuronal endocytic trafficking in adult neurons. Here, we describe a highly effective, quantitative method to measure rapid changes in surface protein expression ex vivo in acute brain slices.
02:33
Preparation and Reactions of Thiols
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2023
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. This reaction fails because the thiol product can undergo a second nucleophilic substitution reaction in the presence of an excess alkyl halide to generate a sulfide as a by-product. This limitation can be overcome by using thiourea as the nucleophile. The reaction first produces an alkyl...
06:43
In Vivo Proximity Biotinylation for Protein Interaction Studies in Paramecium tetraurelia
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Cited by 1 •
2025
The protocol presents a method for in vivo covalent attachment of biotin to proteins based on their proximity to a biotin ligase fused to a protein of interest. This modification allows for a selective enrichment of the proteins using streptavidin beads as needed in protein interaction studies.
FAQs
The choice of thiol-reactive reagent determines how the labeling reaction is initiated, but both maleimides and iodoacetamides can create a covalent link with an accessible cysteine side chain. This chemical attachment converts the selected sulfhydryl site into a biotin-bearing marker, allowing the same labeled molecule to be recognized in later streptavidin- or avidin-based steps.
Accessibility determines whether a cysteine can be reached by the labeling reagent, so cysteine presence alone does not describe the likely labeling pattern. Side chains exposed in the reaction environment are positioned to react, whereas less accessible sites may contribute less to the observed signal. This distinction lets investigators interpret labeling as information about protein surface exposure, not simply cysteine number.
Reaction conditions control both labeling efficiency and selectivity. Adjusting the environment can therefore change how much biotin is attached and how specifically thiol groups are targeted, even when the same reagent and protein are used. Maintaining a controlled reaction is important when comparing samples, because differences in labeling may reflect conditions as well as biological differences.
First, a sample is exposed to a thiol-reactive biotin reagent under controlled conditions that favor reaction with accessible sulfhydryl groups. The resulting covalent labeling creates a biotin handle on the target molecules. The sample can then be analyzed through biotin binding to streptavidin or avidin, supporting downstream detection or isolation.
Streptavidin and avidin provide the recognition step after the covalent chemistry has occurred. Their strong binding to biotin allows labeled molecules to be detected or captured, so the initial cysteine-directed reaction can be translated into an experimental readout. Depending on the study, that readout supports protein isolation, detection, localization, or examination of molecular associations.
In biology, the method can reveal whether cysteine-containing regions are exposed, help follow protein trafficking, and assist in examining molecular associations. These applications connect a chemical label to structural and cellular behavior: labeling patterns can contribute to studies of protein structure and surface exposure, while biotin-based handling helps investigate where proteins go and what they associate with in complex samples.