Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. The name biotin, borrowed from the German Biotin, derives from the Ancient Greek word βίοτος (bíotos; 'life') and the suffix "-in" (a suffix used in chemistry usually to indicate 'forming'). Biotin appears as a white, needle-like crystalline solid.
Streptavidin is a 52 kDa protein (tetramer) purified from the bacterium Streptomyces avidinii. Streptavidin homo-tetramers have an extraordinarily high affinity for biotin. With a dissociation constant (Kd) on the order of ≈10−14 mol/L, the binding of biotin to streptavidin is one of the strongest non-covalent interactions known in nature. Streptavidin is used extensively in molecular biology and bionanotechnology due to the streptavidin-biotin complex's resistance to organic solvents, denaturants, detergents, proteolytic enzymes, and extremes of temperature and pH.
3,3′-Diaminobenzidine (DAB) is an organic compound with the formula (C6H3(NH2)2)2. This derivative of benzidine is a precursor to polybenzimidazole, which forms fibers that are renowned for their chemical and thermal stability. As its water-soluble tetrahydrochloride, DAB has been used in immunohistochemical staining of nucleic acids and proteins.
Protein tags are peptide sequences genetically grafted onto a recombinant protein. Tags are attached to proteins for various purposes. They can be added to either end of the target protein, so they are either C-terminus or N-terminus specific or are both C-terminus and N-terminus specific. Some tags are also inserted at sites within the protein of interest; they are known as internal tags.
Avidin is a tetrameric biotin-binding protein produced in the oviducts of birds, reptiles and amphibians and deposited in the whites of their eggs. Dimeric members of the avidin family are also found in some bacteria. In chicken egg white, avidin makes up approximately 0.05% of total protein (approximately 1800 μg per egg). The tetrameric protein contains four identical subunits (homotetramer), each of which can bind to biotin (Vitamin B7, vitamin H) with a high degree of affinity and specificity. The dissociation constant of the avidin-biotin complex is measured to be KD ≈ 10−15 M, making it one of the strongest known non-covalent bonds.
Cyanines, also referred to as tetramethylindo(di)-carbocyanines are a synthetic dye family belonging to the polymethine group. Although the name derives etymologically from terms for shades of blue, the cyanine family covers the electromagnetic spectrum from near IR to UV.
A tetramer assay is a procedure that uses tetrameric proteins to detect and quantify T cells that are specific for a given antigen within a blood sample. The tetramers used in the assay are made up of four major histocompatibility complex (MHC) molecules, which are found on the surface of most cells in the body. MHC molecules present peptides to T-cells as a way to communicate the presence of viruses, bacteria, cancerous mutations, or other antigens in a cell. If a T-cell's receptor matches the peptide being presented by an MHC molecule, an immune response is triggered. Thus, MHC tetramers that are bioengineered to present a specific peptide can be used to find T-cells with receptors that match that peptide. The tetramers are labeled with a fluorophore, allowing tetramer-bound T-cells to be analyzed with flow cytometry. Quantification and sorting of T-cells by flow cytometry enables researchers to investigate immune response to viral infection and vaccine administration as well as functionality of antigen-specific T-cells. Generally, if a person's immune system has encountered a pathogen, the individual will possess T cells with specificity toward some peptide on that pathogen. Hence, if a tetramer stain specific for a pathogenic peptide results in a positive signal, this may indicate that the person's immune system has encountered and built a response to that pathogen.
Neutralite Avidin protein is a deglycosylated version of chicken avidin, with a mass of approximately 60,000 daltons. As a result of carbohydrate removal, lectin binding is reduced to undetectable levels, yet biotin binding affinity is retained because the carbohydrate is not necessary for this activity. Avidin has a high pI but NeutrAvidin has a near-neutral pI, minimizing non-specific interactions with the negatively-charged cell surface or with DNA/RNA. Neutravidin still has lysine residues that remain available for derivatization or conjugation.
Bissulfosuccinimidyl suberate (BS3) is a crosslinker used in biological research. It is a water-soluble version of disuccinimidyl suberate.
Photobiotin is a derivative of biotin used as a biochemical tool. It is composed of a biotin group, a linker group, and a photoactivatable aryl azide group.
Meir Wilchek is an Israeli biochemist. He is a professor at the Weizmann Institute of Science.
Cell-free protein array technology produces protein microarrays by performing in vitro synthesis of the target proteins from their DNA templates. This method of synthesizing protein microarrays overcomes the many obstacles and challenges faced by traditional methods of protein array production that have prevented widespread adoption of protein microarrays in proteomics. Protein arrays made from this technology can be used for testing protein–protein interactions, as well as protein interactions with other cellular molecules such as DNA and lipids. Other applications include enzymatic inhibition assays and screenings of antibody specificity.
Alice Yen-Ping Ting is Taiwanese-born American chemist. She is a professor of genetics, of biology, and by courtesy, of chemistry at Stanford University. She is also a Chan Zuckerberg Biohub investigator and a member of the National Academy of Sciences.
1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide is a water-soluble carbodiimide usually handled as the hydrochloride.
MHC multimers are oligomeric forms of MHC molecules, designed to identify and isolate T-cells with high affinity to specific antigens amid a large group of unrelated T-cells. Multimers generally range in size from dimers to octamers; however, some companies use even higher quantities of MHC per multimer. Multimers may be used to display class 1 MHC, class 2 MHC, or nonclassical molecules from species such as monkeys, mice, and humans.
Chem-seq is a technique that is used to map genome-wide interactions between small molecules and their protein targets in the chromatin of eukaryotic cell nuclei. The method employs chemical affinity capture coupled with massively parallel DNA sequencing to identify genomic sites where small molecules interact with their target proteins or DNA. It was first described by Lars Anders et al. in the January, 2014 issue of "Nature Biotechnology".
BLESS, also known as breaks labeling, enrichment on streptavidin and next-generation sequencing, is a method used to detect genome-wide double-strand DNA damage. In contrast to chromatin immunoprecipitation (ChIP)-based methods of identifying DNA double-strand breaks (DSBs) by labeling DNA repair proteins, BLESS utilizes biotinylated DNA linkers to directly label genomic DNA in situ which allows for high-specificity enrichment of samples on streptavidin beads and the subsequent sequencing-based DSB mapping to nucleotide resolution.
An artificial metalloenzyme (ArM) is a metalloprotein made in the laboratory which cannot be found in the nature and can catalyze certain desired chemical reactions. Despite fitting into classical enzyme categories, ArMs also have potential in chemical reactivity like catalyzing Suzuki coupling, metathesis and so on, which are never reported in natural enzymatic reaction. With the progress in organometallic synthesis and protein engineering, more and more new kind of design of ArMs came out, showing promising future in both academia and industrial aspects.
Enzyme-catalyzed proximity labeling (PL), also known as proximity-based labeling, is a laboratory technique that labels biomolecules, usually proteins or RNA, proximal to a protein of interest. By creating a gene fusion in a living cell between the protein of interest and an engineered labeling enzyme, biomolecules spatially proximal to the protein of interest can then be selectively marked with biotin for pulldown and analysis. Proximity labeling has been used for identifying the components of novel cellular structures and for determining protein-protein interaction partners, among other applications.
Immunoliposome therapy is a targeted drug delivery method that involves the use of liposomes coupled with monoclonal antibodies to deliver therapeutic agents to specific sites or tissues in the body. The antibody modified liposomes target tissue through cell-specific antibodies with the release of drugs contained within the assimilated liposomes. Immunoliposome aims to improve drug stability, personalize treatments, and increased drug efficacy. This form of therapy has been used to target specific cells, protecting the encapsulated drugs from degradation in order to enhance their stability, to facilitate sustained drug release and hence to advance current traditional cancer treatment.
