Annelid cytochrome P-450

Both classes of Annelida - Polychaeta and Clitellata - have been shown to c ontain cytochrome P-450. The metabolism of a number of aromatic hydrocarbon s, drugs and pesticides by annelids required oxygen and NADPH, and was inhi bited by a variety of cytochrome P-450 inhibitors. A number of types I and II substrates bound. to the cytochrome P-450 in polychaete microsomes to gi ve typical types I and II binding spectra. These results suggest that xenob iotics in annelids are metabolized by a typical cytochrome P-450 mixed func tion oxygenase. In addition to xenobiotics, annelid cytochrome P-450 system s are likely to function in the biosynthesis and metabolism of sterols and hormones found in annelids, such as cholesterol, ecdysteroids and eicosanoi ds. The primary source of cytochrome P-450 isolated to date from annelids h as been intestinal microsomes. Cytochrome P-450 concentrations in these mic rosomes varied from 8 to 580 pmol mg(-1) of protein. The only cytochrome P- 450s purified from annelids were the three isomers isolated from microsomes of the oligochaete, Lumbricus terrestris, whose molecular masses were 4800 0, 51000 and 53000 Da. Work on the induction of cytochrome P-450 in polycha etes by exposure to polycyclic aromatic hydrocarbons or polychlorinated bip henyls has given conflicting results, since some groups found induction aft er such exposure, but others found no induction. One possible explanation m ay be exposure to natural soil and sediments inducers, e.g. plant alkaloids , during feeding. Since gene and protein sequences have yet to be carried o ut on the cytochrome P-450 of any annelid, the relationship of annelid cyto chrome P-450s to the 74 families of P-450 so far found, remains to be carri ed out. (C) 1998 Elsevier Science Inc. All rights reserved.