-
The Journal of Nutrition Aug 2017Although frank symptomatic biotin deficiency is rare, some evidence suggests that marginal biotin deficiency occurs spontaneously in a substantial proportion of women... (Review)
Review
Although frank symptomatic biotin deficiency is rare, some evidence suggests that marginal biotin deficiency occurs spontaneously in a substantial proportion of women during normal human pregnancy and might confer an increased risk of birth defects. Herein I review ) advances in assessing biotin status, including the relation between acylcarnitine excretion and biotin status; ) recent studies of biotin status in pregnancy; ) advances in understanding the role of biotin in gene expression and the potential roles of biotinylated proteins that are neither histones nor carboxylases; and ) novel large-dose biotin supplementation as therapy for multiple sclerosis. The review concludes with a summary of recent studies that have reported potentially dangerous erroneous results in individuals consuming large amounts of biotin for measurements of various plasma hormones for common clinical assays that use streptavidin-biotin technology.
Topics: Animals; Biotin; Biotinylation; Carnitine; Female; Gene Expression; Hormones; Humans; Multiple Sclerosis; Nutritional Status; Pregnancy; Pregnancy Complications; Streptavidin; Vitamin B Complex
PubMed: 28701385
DOI: 10.3945/jn.116.238956 -
Thyroid : Official Journal of the... Aug 2021Biotin has been reported to interfere with several commonly used laboratory assays resulting in misleading values and possible erroneous diagnosis and treatment. This...
Biotin has been reported to interfere with several commonly used laboratory assays resulting in misleading values and possible erroneous diagnosis and treatment. This report describes a prospective study of possible biotin interference in thyroid-related laboratory assays, with a comparison of different commonly used assay platforms. Thirteen adult subjects (mean age 45 ± 13 years old) were administered biotin 10 mg/day for eight days. Blood specimens were collected at three time points on day 1 and on day 8 (baseline, two, and five hours after biotin ingestion). Thyrotropin (TSH), free triiodothyronine (fT3), free thyroxine (fT4), total triiodothyronine (TT3), total thyroxine (TT4), thyroxine binding globulin (TBG), and thyroglobulin (Tg) levels were analyzed with four different platforms: Abbott Architect, Roche Cobas 6000, Siemens IMMULITE 2000, and liquid chromatography with tandem mass spectrometry (LC-MS/MS). TSH, fT3, fT4, TT3, and TT4 were measured with Abbott Architect and Roche Cobas 6000. fT3, fT4, TT3, and TT4 were also measured by LC-MS/MS. Tg was measured by Siemens IMMULITE 2000. TBG was assessed with Siemens IMMULITE 2000. Significant changes in TSH, fT4, and TT3 measurements were observed after biotin exposure when the Roche Cobas 6000 platform was used. Biotin intake resulted in a falsely lower Tg level when measurements were performed with Siemens IMMULITE 2000. At the time points examined, maximal biotin interference was observed two hours after biotin exposure both on day 1 and day 8. A daily dose of 10 mg was shown to interfere with specific assays for TSH, fT4, TT3, and Tg. Physicians must be aware of the potential risk of erroneous test results in subjects taking biotin supplements. Altered test results for TSH and Tg can be particularly problematic in patients requiring careful titration of levothyroxine therapy such as those with thyroid cancer.
Topics: Adult; Aged; Biotin; Chromatography, High Pressure Liquid; False Negative Reactions; Female; Humans; Male; Mass Spectrometry; Middle Aged; Prospective Studies; Thyroglobulin; Thyroid Function Tests; Thyroid Hormones; Thyrotropin
PubMed: 34042535
DOI: 10.1089/thy.2020.0866 -
Genomics, Proteomics & Bioinformatics Feb 2022Proximity labeling catalyzed by promiscuous enzymes, such as APEX2, has emerged as a powerful approach to characterize multiprotein complexes and protein-protein...
Proximity labeling catalyzed by promiscuous enzymes, such as APEX2, has emerged as a powerful approach to characterize multiprotein complexes and protein-protein interactions. However, current methods depend on the expression of exogenous fusion proteins and cannot be applied to identify proteins surrounding post-translationally modified proteins. To address this limitation, we developed a new method to label proximal proteins of interest by antibody-mediated protein A-ascorbate peroxidase 2 (pA-APEX2) labeling (AMAPEX). In this method, a modified protein is bound in situ by a specific antibody, which then tethers a pA-APEX2 fusion protein. Activation of APEX2 labels the nearby proteins with biotin; the biotinylated proteins are then purified using streptavidin beads and identified by mass spectrometry. We demonstrated the utility of this approach by profiling the proximal proteins of histone modifications including H3K27me3, H3K9me3, H3K4me3, H4K5ac, and H4K12ac, as well as verifying the co-localization of these identified proteins with bait proteins by published ChIP-seq analysis and nucleosome immunoprecipitation. Overall, AMAPEX is an efficient method to identify proteins that are proximal to modified histones.
Topics: Ascorbate Peroxidases; Biotin; Biotinylation; Histone Code; Histones; Nucleosomes; Proteome; Staphylococcal Protein A; Streptavidin
PubMed: 34555496
DOI: 10.1016/j.gpb.2021.09.003 -
Annual Review of Plant Biology May 2023Proteins are workhorses in the cell; they form stable and more often dynamic, transient protein-protein interactions, assemblies, and networks and have an intimate... (Review)
Review
Proteins are workhorses in the cell; they form stable and more often dynamic, transient protein-protein interactions, assemblies, and networks and have an intimate interplay with DNA and RNA. These network interactions underlie fundamental biological processes and play essential roles in cellular function. The proximity-dependent biotinylation labeling approach combined with mass spectrometry (PL-MS) has recently emerged as a powerful technique to dissect the complex cellular network at the molecular level. In PL-MS, by fusing a genetically encoded proximity-labeling (PL) enzyme to a protein or a localization signal peptide, the enzyme is targeted to a protein complex of interest or to an organelle, allowing labeling of proximity proteins within a zoom radius. These biotinylated proteins can then be captured by streptavidin beads and identified and quantified by mass spectrometry. Recently engineered PL enzymes such as TurboID have a much-improved enzymatic activity, enabling spatiotemporal mapping with a dramatically increased signal-to-noise ratio. PL-MS has revolutionized the way we perform proteomics by overcoming several hurdles imposed by traditional technology, such as biochemical fractionation and affinity purification mass spectrometry. In this review, we focus on biotin ligase-based PL-MS applications that have been, or are likely to be, adopted by the plant field. We discuss the experimental designs and review the different choices for engineered biotin ligases, enrichment, and quantification strategies. Lastly, we review the validation and discuss future perspectives.
Topics: Biotin; Organelles; Proteins; Streptavidin; Plants
PubMed: 36854476
DOI: 10.1146/annurev-arplant-070522-052132 -
Journal of Visualized Experiments : JoVE Feb 2013Palmitoylation is a post-translational lipid modification involving the attachment of a 16-carbon saturated fatty acid, palmitate, to cysteine residues of substrate...
Palmitoylation is a post-translational lipid modification involving the attachment of a 16-carbon saturated fatty acid, palmitate, to cysteine residues of substrate proteins through a labile thioester bond [reviewed in]. Palmitoylation of a substrate protein increases its hydrophobicity, and typically facilitates its trafficking toward cellular membranes. Recent studies have shown palmitoylation to be one of the most common lipid modifications in neurons, suggesting that palmitate turnover is an important mechanism by which these cells regulate the targeting and trafficking of proteins. The identification and detection of palmitoylated substrates can therefore better our understanding of protein trafficking in neurons. Detection of protein palmitoylation in the past has been technically hindered due to the lack of a consensus sequence among substrate proteins, and the reliance on metabolic labeling of palmitoyl-proteins with (3)H-palmitate, a time-consuming biochemical assay with low sensitivity. Development of the Acyl-Biotin Exchange (ABE) assay enables more rapid and high sensitivity detection of palmitoylated proteins, and is optimal for measuring the dynamic turnover of palmitate on neuronal proteins. The ABE assay is comprised of three biochemical steps (Figure 1): 1) irreversible blockade of unmodified cysteine thiol groups using N-ethylmaliemide (NEM), 2) specific cleavage and unmasking of the palmitoylated cysteine's thiol group by hydroxylamine (HAM), and 3) selective labeling of the palmitoylated cysteine using a thiol-reactive biotinylation reagent, biotin-BMCC. Purification of the thiol-biotinylated proteins following the ABE steps has differed, depending on the overall goal of the experiment. Here, we describe a method to purify a palmitoylated protein of interest in primary hippocampal neurons by an initial immunoprecipitation (IP) step using an antibody directed against the protein, followed by the ABE assay and western blotting to directly measure palmitoylation levels of that protein, which is termed the IP-ABE assay. Low-density cultures of embryonic rat hippocampal neurons have been widely used to study the localization, function, and trafficking of neuronal proteins, making them ideally suited for studying neuronal protein palmitoylation using the IP-ABE assay. The IP-ABE assay mainly requires standard IP and western blotting reagents, and is only limited by the availability of antibodies against the target substrate. This assay can easily be adapted for the purification and detection of transfected palmitoylated proteins in heterologous cell cultures, primary neuronal cultures derived from various brain tissues of both mouse and rat, and even primary brain tissue itself.
Topics: Acylation; Animals; Biotin; Cells, Cultured; Hippocampus; Hydroxylamine; Immunoprecipitation; Lipoylation; Mice; Nerve Tissue Proteins; Neurons; Rats
PubMed: 23438969
DOI: 10.3791/50031 -
Biochimica Et Biophysica Acta May 2001The review is concerned with three Na(+)-dependent biotin-containing decarboxylases, which catalyse the substitution of CO(2) by H(+) with retention of configuration... (Review)
Review
The review is concerned with three Na(+)-dependent biotin-containing decarboxylases, which catalyse the substitution of CO(2) by H(+) with retention of configuration (DeltaG degrees '=-30 kJ/mol): oxaloacetate decarboxylase from enterobacteria, methylmalonyl-CoA decarboxylase from Veillonella parvula and Propiogenium modestum, and glutaconyl-CoA decarboxylase from Acidaminococcus fermentans. The enzymes represent complexes of four functional domains or subunits, a carboxytransferase, a mobile alanine- and proline-rich biotin carrier, a 9-11 membrane-spanning helix-containing Na(+)-dependent carboxybiotin decarboxylase and a membrane anchor. In the first catalytic step the carboxyl group of the substrate is converted to a kinetically activated carboxylate in N-carboxybiotin. After swing-over to the decarboxylase, an electrochemical Na(+) gradient is generated; the free energy of the decarboxylation is used to translocate 1-2 Na(+) from the inside to the outside, whereas the proton comes from the outside. At high [Na(+)], however, the decarboxylases appear to catalyse a mere Na(+)/Na(+) exchange. This finding has implications for the life of P. modestum in sea water, which relies on the synthesis of ATP via Delta(mu)Na(+) generated by decarboxylation. In many sequenced genomes from Bacteria and Archaea homologues of the carboxybiotin decarboxylase from A. fermentans with up to 80% sequence identity have been detected.
Topics: Bacterial Proteins; Biotin; Carboxy-Lyases; Cations, Monovalent; Decarboxylation; Energy Metabolism; Methylmalonyl-CoA Decarboxylase; Models, Chemical; Protons; Sodium
PubMed: 11248185
DOI: 10.1016/s0005-2728(00)00273-5 -
Biochemical Society Transactions Dec 2018Biotin, which serves as a carboxyl group carrier in reactions catalyzed by biotin-dependent carboxylases, is essential for life in most organisms. To function in... (Review)
Review
Biotin, which serves as a carboxyl group carrier in reactions catalyzed by biotin-dependent carboxylases, is essential for life in most organisms. To function in carboxylate transfer, the vitamin must be post-translationally linked to a specific lysine residue on the biotin carboxyl carrier (BCC) of a carboxylase in a reaction catalyzed by biotin protein ligases. Although biotin addition is highly selective for any single carboxylase substrate, observations of interspecies biotinylation suggested little discrimination among the BCCs derived from the carboxylases of a broad range of organisms. Application of single turnover kinetic techniques to measurements of post-translational biotin addition reveals previously unappreciated selectivity that may be of physiological significance.
Topics: Biotin; Kinetics; Protein Processing, Post-Translational; Substrate Specificity
PubMed: 30381340
DOI: 10.1042/BST20180425 -
Nano Letters May 2023The effect of an externally applied directional force on molecular friction is so far poorly understood. Here, we study the force-driven dissociation of the...
The effect of an externally applied directional force on molecular friction is so far poorly understood. Here, we study the force-driven dissociation of the ligand-protein complex biotin-streptavidin and identify anisotropic friction as a not yet described type of molecular friction. Using AFM-based stereographic single molecule force spectroscopy and targeted molecular dynamics simulations, we find that the rupture force and friction for biotin-streptavidin vary with the pulling angle. This observation holds true for friction extracted from Kramers' rate expression and by dissipation-corrected targeted molecular dynamics simulations based on Jarzynski's identity. We rule out ligand solvation and protein-internal friction as sources of the angle-dependent friction. Instead, we observe a heterogeneity in free energy barriers along an experimentally uncontrolled orientation parameter, which increases the rupture force variance and therefore the overall friction. We anticipate that anisotropic friction needs to be accounted for in a complete understanding of friction in biomolecular dynamics and anisotropic mechanical environments.
Topics: Biotin; Streptavidin; Friction; Ligands; Molecular Dynamics Simulation; Microscopy, Atomic Force
PubMed: 36948207
DOI: 10.1021/acs.nanolett.2c04632 -
ACS Applied Materials & Interfaces Dec 2021Biosensors and other biological platform technologies require the functionalization of their surface with receptors to enhance affinity and selectivity. Control over the...
Biosensors and other biological platform technologies require the functionalization of their surface with receptors to enhance affinity and selectivity. Control over the functionalization density is required to tune the platform's properties. Streptavidin (SAv) monolayers are widely used to immobilize biotinylated proteins, receptors, and DNA. The SAv density on a surface can be varied easily, but the predictability is dependent on the method by which the SAv is immobilized. In this study we show a method to quantitatively predict the SAv coverage on biotinylated surfaces. The method is validated by measuring the SAv coverage on supported lipid bilayers with a range of biotin contents and two different main phase lipids and by using quartz crystal microbalance and localized surface plasmon resonance. We explore a predictive model of the biotin-dependent SAv coverage without any fit parameters. Model and data allow to predict the SAv coverage based on the biotin coverage, in both the low- and high-density regimes. This is of special importance in applications with multivalent binding where control over surface receptor density is required, but a direct measurement is not possible.
Topics: Biomimetic Materials; Biotin; Biotinylation; Materials Testing; Streptavidin; Surface Properties
PubMed: 34813287
DOI: 10.1021/acsami.1c16446 -
Molecules (Basel, Switzerland) Dec 2021To improve the tumor-targeting efficacy of photodynamic therapy, biotin was conjugated with chlorin e6 to develop a new tumor-targeting photosensitizer, Ce6-biotin. The...
To improve the tumor-targeting efficacy of photodynamic therapy, biotin was conjugated with chlorin e6 to develop a new tumor-targeting photosensitizer, Ce6-biotin. The Ce6-biotin had good water solubility and low aggregation. The singlet-oxygen generation rate of Ce6-biotin was slightly increased compared to Ce6. Flow cytometry and confocal laser scanning microscopy results confirmed Ce6-biotin had higher binding affinity toward biotin-receptor-positive HeLa human cervical carcinoma cells than its precursor, Ce6. Due to the BR-targeting ability of Ce6-biotin, it exhibited stronger cytotoxicity to HeLa cells upon laser irradiation. The IC50 against HeLa cells of Ce6-biotin and Ce6 were 1.28 µM and 2.31 µM, respectively. Furthermore, both Ce6-biotin and Ce6 showed minimal dark toxicity. The selectively enhanced therapeutic efficacy and low dark toxicity suggest that Ce6-biotin is a promising PS for BR-positive-tumor-targeting photodynamic therapy.
Topics: Antineoplastic Agents; Biotin; Cell Survival; Chlorophyllides; HeLa Cells; Humans; Neoplasms; Photochemotherapy; Photosensitizing Agents
PubMed: 34885922
DOI: 10.3390/molecules26237342