Family of thiomercuric derivatives of sugars: Synthesis, fungicidal/herbicidal activity, and application to the X-ray structure determination of the corresponding enzymes

A series of thiomercuric derivatives of mono- and disaccharides 1-7, in whi ch methylmercury or phenylmercury is covalently attached to anomeric thiogl ycosides, were synthesized for structure-function studies of glycosidases. Thiomethylmercuryl xylobiosides 5 and 6 were found to inhibit intracellular xylanase-T6 in a competitive manner, with K-i values of 0.35 mM and 0.01 m M, respectively. These inhibitors have been co-crystallized with the enzyme and are being used for X-ray analysis. 1-(Thiomethylmercuric)-beta -D-xylo side (3) affords crystals belonging to the orthorhombic space group P2(1)2( 1)2(1) and at 293(2) K: a = 6.7510(2), b = 9.7140(2), c = 29.4770(9) Angstr om, V = 1933.08(9) Angstrom, Z = 8, R(F-2) = 0.0329, and R-w(F-2) = 0.0626. There are two molecules (A and B) in the asymmetric unit, and each one sho ws an almost linear S-Hg-C arrangement. Biological tests on 1-7 indicated t hat they exhibit potent fungicidal and herbicidal activities.