Biophysical and enzymological studies upon the interaction of trans-cinnamic acid with higher plant microsomal cytochromes P-450.
The interaction of trans-cinnamic acid with the cytochrome P-450 of microsomes derived from washed potato slices has been studied. The washing process increased the specific content of microsomal electron transport components and hence provided a useful material in which to study the interaction. Evidence is presented that the trans-cinnamic acid interacts with the cytochrome P-450, and that this interaction is analogous to "type 1" interactions of other cytochrome P-450 systems. This evidence includes the formation of a "type 1" substrate binding spectrum, an increased rate of reduction of cytochrome P-450 by NADPH in the presence of trans-cinnamic acid, an increased oxygen uptake and NADPH oxidation when trans-cinnamic acid is added to the microsomes in the presence of NADPH, and a close correlation between biophysical parameters of electron transport in the cytochrome P-450 system and enzymological parameters of the trans-cinnamic acid 4-hydroxulation reaction. The investigation has been extended to cytochrome P-450 systems of other tissues and it has been found that the trans-cinnamic acid 4-hydroxylation reaction cannot account for the presence of most of th cytochrome P-450 in several tissues. This suggests that other functions of higher plant cytochrome P-450 chains exist, and that the substrate specificityof the hemoprotein may vary in different plant tissues.
D000968:Antimycin A / Q000494:pharmacology; D002934:Cinnamates / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003579:Cytochrome Reductases / Q000378:metabolism; D004790:Enzyme Induction; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008861:Microsomes / Q000378:metabolism*; D010101:Oxygen Consumption; D010944:Plants / Q000378:metabolism*; D013053:Spectrophotometry
D002934:Cinnamates; D000968:Antimycin A; D003577:Cytochrome P-450 Enzyme System; D003579:Cytochrome Reductases