Fluorescent neoglycoproteins: Antibody-aminodextran-phycobiliprotein conjugates

New, highly amino-substituted dextran or aminodextran thereafter denoted Am dex) of various sizes between about 20 and 1000 kDa molecular mass and degr ees of amino-substitution between 7 and 40% were prepared and characterized by elemental analyses and polyacrylamide gel electrophoresis. These aminod extrans together with others commercially available were shown by static li ght scattering, viscosity, and refractive index measurements to adopt a glo bular structure in aqueous salt solutions. Antibody and fluorescent protein dye, phycoerythrin, or its tandems with cyanin 5.1 and TEXAS RED, were cov alently conjugated to the aminodextrans. The conjugates contained multiple dye molecules and were shown by dynamic light scattering and scanning elect ron microscopy to assume either globular structure or aggregates thereof. S treptavidin could be substituted for antibody to prepare streptavidin-amino dextran-PE conjugates, which were then used with biotinylated antibody to l abel subpopulations of white blood cells. The conjugates yielded up to 20-f old amplification of fluorescence intensity over direct antibody-dye conjug ates in labeling white blood cells for flow cytometry.