Biokhimiia. 1990 Oct;55(10):1786-94.  

[Theophylline metabolism by rat liver microsomal monooxygenases]

[Article in Russian]

Vavilin VA, Grishanova AIu, Guliaeva LF, Mishin VM, Liakhovich.

Theophylline metabolism has been studied in a reconstituted monooxygenase system
with purified forms of cytochrome P-450: P-450a, P-450b, P-450d and P-450k as
well as in liver microsomes of control and 3-methylcholanthrene-induced rats.
Cytochrome P-450 isoforms, P-450a and P-450b, had no effect on theophylline
metabolism, whereas forms P-450d and P-450k induced the synthesis of
1.3-dimethyluric acid (1.3-DMA) at the rates of 900 and 330 pmol/min/nmol of
protein, respectively. The catalytic activity of these isoforms was fully
inhibited by homologous monospecific antibodies. P-450c catalyzed the formation
of a nonidentified metabolite. In microsomes of control animals antibodies
specifically directed to cytochrome P-450k suppressed the rate of 1.3-DMA
synthesis by 73%, whereas antibodies specifically raised against P-450c+d--by
11%. In microsomes of methylcholanthrene-induced animals the rate of 1.3-DMA
synthesis was increased two-fold. This activity was inhibited by 61% by
antibodies to cytochrome P-450k and by 18% by anti-P-450c+d antibodies.

PMID: 2078625 [PubMed - indexed for MEDLINE]