Whole IgG antibodies are isolated as intact molecules from antisera by immunoaffinity chromatography. They have an Fc portion and two antigen binding Fab portions joined together by disulfide bonds and therefore they are divalent. The average molecular weight is reported to be about 160 kDa. The whole IgG form of antibodies is suitable for the majority of immunodetection procedures and is the most cost effective.
Alexa Fluor® 488-conjugated antibodies absorb light maximally at 493 nm and fluoresce with a peak around 519 nm. In aqueous mounting media they are brighter than FITC, Cy2, and DyLight 488. Alexa Fluor® 488 conjugates are recommended for maximum sensitivity for all immunofluorescence procedures requiring a green-fluorescing dye, except for protocols that include mounting in plastic mounting media.