In the presence of water, myrosinase cleaves off the glucose group from a glucosinolate. The remaining molecule then quickly converts to a thiocyanate, an isothiocyanate or a nitrile; these are the active substances that serve as defense for the plant.
The glucosinolate-myrosinase defensive system is packaged in the plant in a unique manner. The degradative myrosinase enzymes, which catalyze the hydrolysis of glucosinolate molecules, are largely stored within myrosin grains in myrosin cells, but have also been reported in protein bodies/vacuoles, and as cytosolic enzymes which tend to bind to membranes . When the mechanism isolating the two compounds breaks down, such as by the destruction of plant matter by an herbivore, the myrosinase hydrolization of available glucosinolate substrate occurs.
- ^ Myrosinase structure
- ^ A wound- and methyl jasmonate-inducible transcript coding for a myrosinase-associated protein with similarities to an early nodulin
- ^ Luthy B, Matile P. The mustard oil bomb - rectified analysis of the subcellular organization of the myrosinase system. Biochem Physiol Pfl 179 (1-2): 5-12 (1984).
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