Crystallization of Glutamine Synthetase from Micrococcus glutamicus

For the defense mechanism against pathogenic bacteria in the digestive tracts of silkworm larvae reared on mulberry leaves, in vitro evidence of the formation of a true antibacterial substance was obtained. Caffeic acid (CA) derived from chlorogenic acid (ChA) was converted into caffeoquinone (CQ) by base-catalyzed oxidation in a buffer solution (pH 10.0). CQ was trapped as 6′- phenylsulfonylcaffeic acid (6′-sulfone) by the addition of benzenesulfinic acid (BSA).

The synergistc effects of amino compounds on the antibacterial activity of CQ are discussed in detail, and the probable reactions of CA with amino and thiol compounds in the alkaline solution are proposed.