Sinorhizobium meliloti can be protected from osmotic stress by the presence of certain disaccharides. Dan Orr (’09) found that sucrose does a fine job as an osmoprotectant for our strain of S. meliloti, but maltose and cellobiose don’t work very well to protect it from osmotic stress.

A. What are two significant structural differences between the good osmoprotectant sucrose and the poor osmoprotectants cellobiose and maltose?

B. If trehalose were found to be a good osmoprotectant, what would that suggest is the critical structural difference between good and poor osmoprotectants?