Biotin absorption

Following absorption, biotin enters the portal circulation. It is stored primarily in the liver and kidneys, although all cells contain some biotin. 

Purify the modified protein from unreacted biotinylation reagent and reaction by-products using dialysis or gel filtration. Complete removal of the excess reagent is necessary to provide accurate measurement of the biotin incorporation level by absorptivity. 

The dye HABA interacts with avidm yielding a complex with an absorption maximum at 500 nm. Biotin, because of its higher affinity, displaces HABA, causing a decrease in absorbance at 500 nm proportional to the amount of biotin present in the assay. 

Fig. 4. Schematic of a single-step array fabrication process for in vivo biotinylated proteins. Step a A cmde lysate containing the desired biotinylated recombinant protein is printed onto a streptavidin-coated surface coderivatized with a polymer that resists nonspecific protein absorption. Step b Unbound proteins are washed away to leave the purified recombinant protein, specifically immobilized and oriented on the array surface via the biotin moiety on the BCCP tag.

The use of gold nanoparticles as an electrochemical label for bionanalysis was introduced by Costa-Garcia and coworkers 62 Adsorptive voltammetry was used to detect the gold signal and monitor biotin-stieptavidin interactions on a pretreated carbon paste electrode with an adsorbed biotinylated albumin layer after immersion into a solution of streptavidin-coated colloidal gold. While colloidal gold had found widespread use as a histochemical label for biomolecules and an optical label based on absorption... 

Deficiency can be due to two known genetic disorders of biotin metabolism or be induced by excess intake of avidin, which binds biotin and thus leads to poor absorption. Symptoms are alopecia, eczema around nose and mouth, conjunctivitis, hyperaesthesia, paraesthesia, depression, and muscle pain 29 The recommended daily allowance is 30 to 35 fig.112... 

The rate of avidin absorption was found to be four times less with 2 mol% PEG750 than the unmodified surface while 10 mol% PEG750 completely suppressed binding of avidin to biotin. 

New rhenium(I) biotin complexes containing the extended planar diimine ligands dppz and dppn (17) have been prepared to explore bifunctional biological probes [44], These complexes bind to double-stranded calf thymus DNA by intercalation, as revealed by absorption and emission titrations. HABA assays show that all the complexes bind to avidin with a stoichiometry of 4 1 ([Re] [avidin]). Similar to other rhenium(I) diimine biotin complexes described above, the emission intensities... 

The intestinal absorption of pantothenic acid is by use of the same sodium-dependent carrier as biotin and lipoic acid (Section 11.1). The carrier is found throughout the intestinal tract, and therefore pantothenic acid synthesized by intestinal bacteria (Section 12.2.4) will, like biotin, be available for absorption (Said et al., 1998 Chatterjee et al., 1999 Ramaswamy, 1999 Said, 1999 Prasad... 

Ramaswamy K (1999) Intestinal absorption of water-soluble vitamins focus on molecular mechanism ofthe intestinal biotin titLnspottprocess. AmericanJournalofPhysiology 277, C603-4. 

DEFICIENCY Deficiency of biotin is rare except in people who only eat raw eggs, as egg whites contain avidin, a protein that inhibits biotin absorption. There may be a dermatitis. 

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