Inhibition of the Na+/glucose cotransporter functional lysyl residues by 4-(4-methoxy-3-sulfophenyl)-2,6-bis(4-sulfophenyl)pyryl ium.
Pyrylium salts react exclusively with the epsilon-amino group of lysyl moieties and display a degree of selectivity exceeding all other known amino group reagents. This study represents the first use of a pyrylium salt in positively identifying the functional role of lysyl residues in a biologically active molecule, the Na+/glucose cotransporter protein. We synthesized a hydrophilic pyrylium salt, 4-(4-methoxy-3-sulfophenyl)-2,6-bis(4-sulfophenyl)pyryliu m perchlorate, which formed a stable pyridinium cation upon reaction with N alpha-acetyl-L-lysine methyl ester. This pyrylium inhibited Na+/glucose cotransporter activity in purified brush border membranes, in a concentration-dependent manner. The data unequivocally establish that critical lysyl residues are responsible for the activity of the membrane-bound glucose cotransporter protein.
Fernandez
A
A
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610-0274.
Katritzky
A R
AR
Sutharchanadevi
M
M
Stevens
B R
BR
D000818:Animals; D001557:Benzenesulfonates / Q000494:pharmacology*; D001665:Binding Sites; D007421:Intestine, Small / Q000378:metabolism; D007700:Kinetics; D008239:Lysine; D008871:Microvilli / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000037:antagonists & inhibitors*; D009130:Muscle, Smooth / Q000378:metabolism; D011485:Protein Binding; D011714:Pyrans / Q000494:pharmacology*; D011817:Rabbits; D013053:Spectrophotometry
D001557:Benzenesulfonates; D009004:Monosaccharide Transport Proteins; D011714:Pyrans; C058969:4-(4-methoxy-3-sulfophenyl)-2,6-bis-(4-sulfophenyl)pyrylium; D008239:Lysine