Peptide Coupling
Peptide Coupling - Related Videos
06:09
Quantification of Proteins Using Peptide Immunoaffinity Enrichment Coupled with Mass Spectrometry
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Cited by 37 •
2011
Stable Isotope Standards and Capture by Anti-Peptide Antibodies (SISCAPA) couples affinity enrichment of peptides with stable isotope dilution mass spectrometry (MRM-MS) to provide quantitative measurement of peptides as surrogates for their respective proteins. Here we describe the protocol using magnetic particles in a partially automated format.
04:00
Immunoaffinity Based Extraction of Ubiquitinylated Peptides: A Technique to Selectively Extract Ubiquitin Tagged Peptides from Purified Peptide Fractions
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2023
This video describes a method to extract and purify ubiquitinylated peptides containing remnant di-glycine peptides from a complex peptide mixture. The presented method may help in identifying original ubiquitination sites in the protein.
01:20
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
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2024
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others. The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
01:22
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
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2024
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive. The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
06:19
Palladium-Catalyzed Cross Coupling
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2023
Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the concept of a palladium-catalyzed cross coupling. The set-up of a typical Pd-catalyzed cross coupling reaction will be illustrated. Pd-catalyzed cross coupling reactions have had a profound effect on how synthetic chemists create molecules. These reactions have enabled chemists to construct bonds in new and more efficient ways. Such reactions have found widespread...
FAQs
Selectivity depends on which carboxyl and amino groups remain chemically available. A coupling reagent activates the chosen carboxyl group, while a base supports reaction with the intended protected amino group. Protecting groups temporarily suppress competing functional groups, allowing each cycle to form the desired sequence connection rather than an uncontrolled mixture of products.
Protecting groups help direct peptide coupling toward one planned amide bond by masking amino or other reactive functionalities. They also help limit racemization, a change in the stereochemical configuration of an amino acid that can compromise peptide identity. Careful protection and later deprotection therefore support both sequence control and product quality.
Solid-phase peptide synthesis builds a sequence through repeated coupling and deprotection cycles while the growing material remains associated with a solid support. Solution methods instead assemble peptide fragments in a mobile reaction mixture. The two approaches provide different routes to sequence construction, with fragment assembly particularly relevant when combining larger prepared sections.
A typical cycle selects the next protected amino acid or peptide fragment, activates its carboxyl group with a coupling reagent, and allows reaction with the available protected amino group. After the new amide bond forms, a deprotection step exposes the next reaction site. Repeating this sequence progressively constructs the intended peptide.
Researchers may use solution-based fragment assembly when they need to join previously prepared peptide sections rather than extend a chain one amino acid at a time. This approach is especially relevant to constructing defined sequences from larger components. The resulting amide-bond connections preserve the planned order of fragments and support controlled peptide preparation.
Peptides produced through controlled coupling support biochemical research, pharmaceutical development, diagnostic studies, and materials chemistry. Because the process enables defined sequences, investigators can prepare molecules whose composition and order are specified for their intended study. Repeated synthesis cycles or fragment joining provide adaptable routes for generating these research and applied materials.