STRUCTURE OF EFFECTIVE MONOSACCHARIDES IN STIMULATION OF THE SUGAR RECEPTOR OF THE FLY

Abstract

(1) The change of the stimulating effectiveness accompanied by the mutarotation of β-D-fructopyranose and of α-D-galactopyranose was studied on the sugar receptor of the fleshfly, Boettcherisca peregrina. (2) Response-concentration curves for both fresh (0.5 min after dissolution) and equilibrium solutions of D-fructose were explained by the assumption that only β-D-fructofuranose is effective and co-existing β-D-fructopyranose is competitively inhibitive. Changes in the magnitude of response accompanied by the mutarotation of 0.1 or 0.2 M β-D-fructopyranose were also explained by the same assumption. (3) The responses to fresh solutions of α-D-galatopyrane were extrapolated to be zero at the beginning of dissolution, and increased in magnitude as α-D-galactopyranose interconverted to βform. This indicates that β-galactopyranose is effective in the solution. (4) From these and other results, monosaccharides were classified into two classes, those effective in pyranose and furanose forms, respectively. The pyranose class was further classified into four sub-classes according to the positions of equatorial hydroxyl groups. Such a classification revealed the relation between the molecular structure and the effectiveness.