Synthetic neoglycoproteins: a class of regents for detection of sugar-recognizing substances

Specific interactions between proteins and sugars have recently been emphasized in many biological systems. To detect sugar-recognizing substances, known as lectin-like substances or endogenous lectins, we describe a method in which various sugars were covalently bound to a carrier protein such as albumin. This neoglycoprotein was stable at -20 degrees C for a period of 6 months. It was conjugated to various cytochemical markers (125I, fluorescein isothiocyanate, colloidal gold, or latex minibead). Detection of the marker then indicates the presence of the sugar-binding protein. Control experiments in the presence of unlabeled neoglycoprotein or specific sugar indicated the specificity of the reaction. This method was used to analyze the kinetics of binding for a mannose-recognition system in the mouse peritoneal macrophages. The data obtained were in agreement with those previously reported. The method can be used for detection of other sugar-recognizing systems as virtually every simple sugar can be bound to a carrier protein to produce these neoglycoproteins. Some of the consideration required for successful production of these reagents are discussed. These synthetic neoglycoproteins are useful in studying the distribution and kinetics of sugar-recognizing systems and may help to further our understanding of this rapidly developing area.