The biosynthesis of cyanogenic glucosides in seedlings of cassava (Manihot esculenta Crantz)

摘要: Abstract A microsomal system catalyzing the in vitro synthesis of aglycones two cyanogenic glucosides linamarin and lotaustralin has been isolated from young etiolated seedlings cassava ( Manihot esculenta Crantz). prerequisite to obtain active preparations is complete removal endosperm pellicle covering cotyledons before seedling homogenization. The rates conversion parent amino acids valine isoleucine their cyanohydrins are 19 6 nmol/h/mg protein, respectively. for corresponding oximes (2-methylpropanal oxime 2-methylbutanal oxime) 475 440 protein nitrites (2-methylpropionitrile 2-methylbutyronitrile) 45 75 protein. With exception 2-cyclopentenylglycine, none additionally tested metabolized, whereas a broad substrate specificity observed using nitriles as substrates. biosynthesis photoreversibly inhibited by carbon monoxide, demonstrating involvement cytochrome P450 hydroxylation processes. All tissues contain glucosides. enzyme responsible restricted petioles. This demonstrates that actively transported other parts seedling. activity decreases with height barely detectable above mm.