Agglutination of Bacterial Spheroplast

III. Relationship of Labelled Concanavalin A Binding to the Agglutinability

Abstract

⁶³Ni- and ³H-acetyl labelled concanavalin A's (con A) were tound to agglutinate protease-treated spheroplasts of E. coli by about one-third and slightly less than the original con A, respectively. However, both radioactively labelled con A derivatives apparently bound to the spheroplasts in the same manner. The total amount of labelled con A's bound per spheroplast was slightly less with protease-treated spheroplasts than non-treated ones, which were not agglutinated by con A. The number of con A molecules bound per spheroplast was in the range of 6-8×10⁵, approximately one-hundredth of the molecules bound to a transformed mammalian cell, as reported elsewhere. Methyl α-D-glucoside (αMG) showed at most 50% inhibition of con Abinding at a concentration sufficient to inhibit agglutination completely
Specific binding of con A molecules to αMG sites was found to be higher with protease-treated spheroplasts (2.7-3.8×10⁵) than with non-treated ones (2.2-2.4×10⁵). When incubation was performed at temperatures lower than 37°C, than agglutination was reduced greatly or completely at 0°C, whereas the binding was inhibited by only 20% at most. From these results the relationship between the binding of con A on the spheroplast surface and the inhibition of agglutination was discussed in relation to observations in the transformed animal cell-con A system.