Biotin-4-fluorescein (<i>N</i>-(5-aminopentyl)biotinamide, trifluoroacetic acid salt) has been reported to be a superior fluorescent biotin derivative for accurate measurement of avidin and streptavidin in crude biological samples. Binding of biotin to avidin and streptavidin is high affinity, fast and noncooperative.
<ul>
<li>&lamba;_Ex/&lamba; _Em = 494/523 nm</li>
<li>Yellow solid soluble in DMSO, or pH&gt;7 buffers</li>
<li>Store at 4°C and protect from light</li>
<li>C₃₃H₃₂N₄O₈S</li>
<li>MW: 644.7</li>
</ul>