Conversion of @entity8454 into haem by liver homogenates. Comparison of XXXX and @entity1573 embryo.

@entity8798 @entity8197 @entity42136 @entity10473 @entity7888 @entity1573 @entity35 @entity8454
1. We have studied the kinetics of the conversion of @entity8454 into haem and haem precursors in homogenates of livers of @entity35 and @entity1573 embryos. Homogenates of fresh liver from both species efficiently convert @entity8454 into haem. After frozen storage for 1 year, homogenates of @entity35 , but not @entity1573 , liver have decreased rates of formation of haem with accumulation of more @entity7888 . The rate of haem formation after storage is restored by addition of @entity8798 and @entity8197 . 2. At all initial concentrations of @entity8454 tested (2 microM-1 mM), homogenates of @entity35 liver accumulate less @entity7888 than haem. In contrast, homogenates of @entity1573 embryo liver accumulate more @entity7888 than haem at concentration of @entity8454 greater than 10 microM. Conversion of @entity7888 into haem by homogenates of fresh or frozen @entity1573 embryo liver is not increased by addition of @entity8798 . 3. Homogenates of liver from both species accumulate porphobilinogen; the kinetic parameters for this process reflect those of @entity8454 dehydratase. 4. The results show that the rate-limiting enzyme for the hepatic conversion of @entity8454 into @entity7888 is @entity10473 deaminase. In addition, @entity1573 liver, compared with @entity35 liver, has only about one-fifth the activity of @entity42136 , the final enzyme of the haem biosynthetic pathway, which inserts @entity8798 into @entity7888 to form haem. 5. Comparison of these results with previous studies indicates that the homogenate system described here provides physiologically and clinically relevant information for study of hepatic haem synthesis and its control.
