AnaSpec Introduces Line of HABA-Biotin Quantitation Kits
Product News Jan 24, 2008
AnaSpec has introduced a new line of HABA Biotin Quantitation Kits. These kits can provide a method for estimating the molar ratio of biotin to protein on biotinylated conjugates. They can also be used to quantitate the biotin concentration in a solution.
Available in two sizes:
• 120 Assays 72096-120 (120 assays in a 96-well format or 25 assays in a cuvette format)
• 500 Assays 72096-500 (500 assays in a 96-well format or 100 assays in a cuvette format)
Biotin and avidin (or streptavidin) bind non-covalently with a higher binding affinity than most antigen-antibody interactions. This very tight binding makes labeling proteins with biotin a useful tool for applications such as affinity chromatography and immunoanalytical assays.
The assay utilizes the observation that HABA (4’-hydroxyazobenzene-2-carboxylic acid) shows dramatic spectral changes when it binds to avidin.
Free HABA has an absorption peak at 348 nm, while the HABA/avidin complex has strong absorption at 500 nm.
Since the affinity between HABA and avidin is relatively weak (Kd=5.8 x 10-6 M) compared to the affinity between biotin and avidin (Kd=1 x 10-15 M), biotin can replace HABA from the HABA/avidin complex, resulting in a decrease of absorption at 500 nm. Avidin and HABA at an optimal ratio are included in the assay kit. The kit has a linear range of 2 to 16 mM.