Factors that Affect the Induction of ALA-Synthetase

In this section, the activities of inducing chemicals are discussed in relation to their destruction by the liver microsomal oxygenase system the rate of heme synthesis and breakdown is considered in relation to the inhibitory properties of heme on the synthesis of ALA-synthetase and the contrasting effects of glucose and starvation are summarized in relation to their effects on induction. 

Inducing Chemicals and the Microsomal Oxygenase System of the Liver 

Esters and amides, which are sterically hindered so that hydrolysis is diminished, probably retain their ALA-synthetase-inducing activity for a longer time—for example, DDC [10,82]. Enzyme reactions that saturate the double bonds of such steroids as progesterone, and hydroxyl groups in steroids or terpenes that are oxidized to keto groups, will tend 

Many of the lipophilic chemicals that induce the synthesis of ALA-synthetase also induce a set of concomitant reactions which help to dispose of these chemicals. Those chemicals that cannot be readily converted to a water-soluble form are as a last resort oxidized in the liver by a microsomal oxygenase system that primarily uses NADPH and O2 to generate OH for hydroxylation [Guroffc al., 83]. 

The oxidations that occur in the microsomes are considered to be catalyzed by two interconnecting pathways [Estabrook and Cohen, 84], 

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