Skip to main content Accessibility help
×
Hostname: page-component-78c5997874-g7gxr Total loading time: 0 Render date: 2024-11-05T02:12:37.303Z Has data issue: false hasContentIssue false

8 - Metabolism

Published online by Cambridge University Press:  07 September 2010

Get access

Summary

Introduction

Polycyclic aromatic hydrocarbons are metabolized by the mixed function oxidase system to forms more readily excretable by the cell; usually by making the PAH more polar and therefore more water soluble. The principal enzymes involved in this process are those consisting of the haem-containing cytochrome P-450 (which requires both NADPH and molecular oxygen) and epoxide hydrolase. These enzymes are located mainly as membrane-bound proteins in the endoplasmic reticulum or nuclei of cells although some cytosolic forms are known. They exist in ‘multiple forms’ some of which have been isolated and purified. These isoenzymes, which are present in a variety of tissues, can be selectively induced by treatment of the animal with various chemicals (commonly used cytochrome P-450 inducers are 3-MC and phenobarbital), and these various induced states can result in different metabolic pathways for the compounds under study.

Cytochrome P-450 introduces a hydroxyl group into an alkyl group, or an epoxide group across the double bond of an aromatic system. Epoxide hydrolase can then metabolize the epoxide further to a trans-dihydrodiol. If this trans-dihydrodiol contains an adjacent double bond then cytochrome P-450 may act for a second time to form a diol epoxide. Although these events are designed as detoxification routes current evidence suggests that the formation of a diol epoxide, particularly a bay-region diol epoxide, are in fact steps of metabolic activation.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 1988

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×