Background:

UltraAvidin™ is Leinco Technologies' trademark for a uniquely modified form of avidin which is isolated from chicken egg whites. With a molecular weight of 60,000, there are four identical subunits each capable of binding one molecule of biotin. UltraAvidin from Leinco Technologies has been de-glycosylated to prevent carbohydrate moieties from adhering to lectin-like receptors on the surface of cells, thus eliminating the possibility of false positives. Unlike native avidin, UltraAvidin has a near neutral pI which prevents electrostatic interactions with negatively charged serum or membrane proteins.

Recent studies have identified a universal recognition sequence in streptavidin which is similar to that found in several adhesion receptors.(1) It is a tripeptide sequence Arg-Tyr-Asp (RYD) which mimics the Arg-Gly-Asp (RGD) binding sequence of fibronectin. Strong interactions have been shown with streptavidin and cell surface molecules. This universal recognition sequence is not present in UltraAvidin. UltraAvidin may not significantly increase sensitivity in all research systems but will help assure specificity.

Allophycocyanin (APC) has a molecular weight of 104 kDa and is purified from green algae. APC is an intensely bright phycobiliprotein with a broad absorption profile that peaks at ~650 nm, and a fluorescence emission maximum of ~660 nm.