Enzymatic processes, regulatory

Phosphate and bicarbonate ions are important substrates for many enzymatic processes and as such have regulatory functions. Bicarbonate controls the key enzyme of photosynthesis, ribulose bisphosphate carboxylase, by carbamate formation (Fig. 13-12). Chloride ions activate amylases and may affect the action of "G proteins" that mediate hormone actions. Other observed effects of ions are too numerous to mention. 

The following conclusions can be made with regard to current knowledge of the lignification process 1) strict enzymatic control leading to the final product apparently does not occur and 2) both regulatory processes controlling its deposition and structure in situ are poorly understood. 

There is ample documentation, obtained primarily in mammals, for the concept that the biosynthesis of the great majority of regulatory neuropeptides occurs by way of enzymatically cleaved large precursor molecules produced under the direction of mRNA templates. Future work will have to show to which extent these and the subsequent steps (posttranslational processing, release, and degradation of these products) also occur in insects. 

---