Demand theory

A DFT-HSAB study provides a quantitative rationalization of regioselectivity in 1,3-DC of 4-substituted benzonitrile oxides towards methyl propiolate not amenable to FMO and electron-demand theory <06CEJ1156>. 

Represslble Biosynthetic Systems. In enteric bacteria the represslble systems for histidine and tryptophan biosynthesis provide examples of systems controlled by positive and negative elements, respectively (see Table IV). Since the level of histidine In the colon Is among the lowest of all amino acids, expression of the histidine biosynthetic operon In the bacterium will be In hl demand (Table III). Thus, demand theory predicts that the histidine biosynthetic operon will be positively regulated (Table II). In fact, there Is good evidence to show that this operon Is controlled primarily by an antiterminator mechanism (, ). On the other hand, the level of tryptophan In the colon Is among the hipest of the amino acids and, therefore, expressl( i of the tryptophan biosynthetic operon In the bacterium... 

The justification for this formalism Is based solidly on theoretical grounds (, 6,3) as well as agreement with direct experimental observations (42,9,Jl). An appreciation of Its utility Is perhaps best gained by an examination of successful applications. Numerous examples can be found elsewhere (43-W, J ,6,3,24), but the limitations of space have precluded dlscu Tng more than one example, the development of the demand theory of gene regulation. 

This demand theory Is now supported by experimental evidence from more than 40 systems representing more than a dozen different types of physiological functions. This theory provides a simple unified explanation for what otherwise would be unconnected and disparate observations. Furthermore, It provides a wealth of specific, testable predictions that can serve as a guide for experimental Investigation (e.g., see Refs. 4 , and Table IV). 

According to demand theory the partial effect of an increase in the price of gasoline is to lower the quantity consumed. For one estimate of this relationship see Glenn Blomquist The 55 MPH Speed Limit and Gasoline Consumption Resources and Energy 6 (March 1984) 21-39. 

---