What are the microsomal enzymes?
There are several microsomal enzymes, including flavin monooxygenases, cytochrome P450, NADPH cytochrome c reductase, UDP Glucoronosyl transferases (UGT), glutathione-S-transferases, epoxide hydrolases, etc. Cytochrome P450 and NADPH cytochrome c reductase are the two main enzymes in this system.
Which microsomal enzyme metabolize most of the drugs?
cytochrome P-450
The most important enzyme system of phase I metabolism is cytochrome P-450 (CYP450), a microsomal superfamily of isoenzymes that catalyzes the oxidation of many drugs.
What are drug-metabolizing enzymes?
Drug-metabolizing enzymes are called mixed-function oxidase or monooxygenase and containing many enzymes including cytochrome P450, cytochrome b5, and NADPH-cytochrome P450 reductase and other components.
Which drug is microsomal enzyme inhibitor?
Microsomal enzyme inducing drugs such as phenytoin, phenobarbital and carbamazepine, and also alcohol, influence serum lipid and apoprotein concentrations. The inducers increase the concentrations of hepatic microsomal enzyme and apo A-I mRNA, and also proteins and phospholipids.
What is microsomal oxidation?
The microsomal ethanol oxidizing system (MEOS) is an alternate pathway of ethanol metabolism that occurs in the smooth endoplasmic reticulum in the oxidation of ethanol to acetaldehyde.
Which of the following types of drug-metabolizing enzymes are inducible?
Several species of cytochrome P-450 are inducible as are certain conjugating enzymes such as glutathione S-transferases, glucuronosyl transferases, and epoxide hydrolases. Induction of drug-metabolizing enzymes has been shown in several instances to alter the efficacy of some therapeutic agents.
What is microsomal metabolism?
Liver microsomes are subcellular fractions which contain membrane bound drug metabolizing enzymes. Microsomes can be used to determine the in vitro intrinsic clearance of a compound. The use of species-specific microsomes can be used to enable an understanding of interspecies differences in drug metabolism.
Where are drug metabolizing enzymes?
Drug-metabolizing enzymes are both present and active in the fetal liver, albeit at reduced levels compared with the adult liver for most enzymes.
What are drug enzymes?
Drug metabolizing enzymes are responsible for degradation of drugs and environmental pollutants and are important determinants of drug action. An example is the polymorphism in acetylation that is mediated by N-acetyltransferase isoenzymes NAT1 and NAT2 in the liver (2R).
What is the main enzyme for microsomal oxidation?
The microsomal ethanol oxidizing system (particularly the enzyme P-450 2E-1) is highly inducible by alcohol and promotes the conversion of alcohol to acetaldehyde.
What is oxidation in drug metabolism?
A common Phase I oxidation involves conversion of a C-H bond to a C-OH. This reaction sometimes converts a pharmacologically inactive compound (a prodrug) to a pharmacologically active one. By the same token, Phase I can turn a nontoxic molecule into a poisonous one (toxification).
Which of the following enzymes is known to metabolize drug compounds?
Drug metabolizing enzymes, particularly the cytochrome P450 enzymes, are very important in the detoxification of many chemicals (see Biochemical and Molecular Basis of Toxicity, Vol 1, Chap 2).
What are the enzymes in liver microsomal drug-metabolism?
The liver microsomal drug-metabolizing enzyme system consists of two protein components, cytochrome P-450 and NADPH-cytochrome c reductase, and a lipid, phosphatidylcholine. Cytochrome P-450 serves as the binding site for oxygen and substrate while the reductase acts as an electron carrier shuttling …
Drug metabolizing enzymes are present in exocrine pancreatic tissue and are inducible by the administration of certain chemicals. Drug-metabolizing enzymes may be modulated by: increase of the amount of enzyme protein (‘induction’ in the broad sense of the term, usually but not always due to transcriptional activation);
What are microsomal enzymes?
Microsomal enzymes, offer some explanation for a number of otherwise obscure facts in toxicology. It is generally admitted that the net effect of these enzymes is adaptive for the organisms, but it has been suggested that stimulation of enzymes by one chemical will lead to greater injury to the organism when faced with some other challenge.
What is an example of a metabolizing enzyme?
Drug metabolizing enzymes are responsible for degradation of drugs and environmental pollutants and are important determinants of drug action. An example is the polymorphism in acetylation that is mediated by N-acetyltransferase isoenzymes NAT1 and NAT2 in the liver (2R).
