One of the simple sugars galactose or mannose used in this e

One of the simple sugars (galactose or mannose) used in this exercise should have inhibited Con A-peroxidase binding to cheek epithelial cells and the Con A-induced hemoagglutination reaction. Name this sugar and describe the mechanism by which it inhibits these effects. Describe the mechanism responsible for the Con-A induced hemoagglutinating reaction. Most membrane proteins including the Con-A receptor can be solubilized by treating cell membranes with a non-ionic detergent such as Triton X 100. You are given such a soluble preparation of erythrocyte proteins. Describe a single procedure that could be used to isolate the Con A Receptor from this preparation.

Solution

Ans 1: This is competitive inhibition. The concanavalin A has a higher specificity for mannose rather than galactose. Mannose binds to and occupies the mannose-binding site on Con A, making it unavailable for binding to mannose residues on the cell surface, which are present at much lower concentration.

Ans 2: Though the binding of concanavalin A (Con A) to the cell surface was very specific, the cell agglutina- tion induced by Con A was due to the topographical distribution of the surface receptors for the lectin, and not the result of energy-dependent or microtubule-dependent reaction pro- cesses. However, the rate and degree of intercellular adhesion in the presence of controlled shear forces. The number and the state of Con A receptors on the cell surface were in a dynamic condition, their conformation, orientation, and/or topographical distribution changing under different conditions.