ABSTRACT
P (biochemistry) An abbreviation of ‘P ’rol ine.
P450 (genetics) A GENE superfamily, consisting of large groups of genes that code for proteins (CYTOCHROMES) which metabolise drugs or other foreign chemicals. The P450 CYTOCHROMES are coded for by 20 different famil ies of genes, ten of which are the same in all mammals. Any one mammalian SPECIES may have between 60 and 200 individual P450 genes, each making a unique CYTOCHROME. The drug or chemical acts in many cases as the INDUCER for the relevant P450 GENE. In humans, POLYMORPHISMS of P450 genes are responsible for many of the examples of pat ients ’ VARIABLE responses to cl inical drugs.
