Sulfate esters insects

Balance between the active and inactive forms of ecdysone and/or other ecdysteroids may be accomplished by the formation of conjugates such as sulfate esters or glucosides (20,27). The sulfation of phenols and a variety of sterols has been 3emonstrated in insect tissues and this, in close association with an appropriate sulfatase, would constitute a readily reversible mechanism whereby the required balance between active and inactive forms of ecdysteroids could be regulated (27). 

One of the least active compounds in the insect bioassay was the 2-sulfate ester of L-ascorbic acid. To develop normally the hornworm... 

The ability of insect sulfotransferases to catalyze the sulfation of plant and insect steroids may simply reflect the broad substrate specificity of the enzymes. On the other hand, it may be indicative of a more important physiological function of the enzymes. Sulfate esters of cholesterol, campesterol and e-sitosterol have been identified in the meconium of tobacco hornworm (M. sexta) pupae ( ), and these steroids are known precursors of a-and e-ecdysone and other molting hormones in this species ( ). Further, there is evidence that houseflies (M. domestica) and diapausing pupae of M. sexta convert 22,25 bisdeoxyecdysone, a-ecdysone and 20-hydroxyecdysone into sulfate and glucoside conjugates ( ). 

O-sulfate ester. Both gastrin and CCK molecules are partially converted to sulfate esters. 4i9 Most regions of the brain contain CCK peptides in amounts exceeding those of other neurotransmitters. These arise (in pigs) from a 114-residue preproCCK. The sul-fated insect neuropeptide, leukosulfakinin (Table... 

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