Streptavidin (PE)

Streptavidin is a 55 kDa (subunit MW 14 kDa) biotin-binding protein isolated from Streptomyces avidini. Streptavidin is superior to avidin, because it does not contain carbohydrate like avidin and has no net charge at neutral pH. Streptavidin~biotin system is routinely used in Immunohistochemistry (IHC). Extinction Coefficient 1% A28=32.. Purity: > 99% pure by HPLC; Eletrophoretically homogenous, single band. Protein content: > 95%; Activity 14.8 units/ mg, one unit bunds 1. microgram of d-biotin; Protease activity: .18 units/mg; Isoelectric point: 7. +/- determined by Isoelectric focusing. Phycoethyrin (R-PE) is a 24 kDa phycobilliprotein found in red, macrophytic algae (seaweed). R-PE can be used with Fluorescein (FITC) for double labeling in flow cytometry using argon laser, since both R-PE and FITC can be excited at 488 nm, and R-PE fluoresces at a longer wavelength (58 nm) than FITC (52 nm). Phycoethyrin: R-PE purified from Poryhyra tenera; A565/A28 >5.; A 1% 565 nm=82; Amax = 49, 545 and 566 nm; E max = 58 nm.