They indicate that the metabolism of quinate ester and tyramine amide of p-coumaric acid rely on the same recognition site in the protein. Homology modeling, confirmed by directed mutagenesis, provides information on the protein regions and structural features important for some observed changes in substrate selectivity. One of the most significant is meta-hydroxylation of p-coumaroyltyramine, predominantly by the wheat enzymes, for the synthesis of suberin phenolic monomers. The expression profiles suggest specific or overlapping functions in olfaction, detoxification and pheromone biosynthesis. Cytochromes P450 ( P450s or CYPs) are a superfamily of enzymes containing heme as a cofactor that mostly, but not exclusively, function as monooxygenases.
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Some of them might be significant in the metabolism of various free or conjugated phenolics in different plant species. ponderosae antennae showed that transcripts of many of the P450 genes that are present in the antennae are also abundant in the midgut and fat body 4. However, CYP98s from divergent taxa have acquired different additional subsidiary activities. Expression, function and regulation of mouse cytochrome P450 enzymes: comparison. Three of the eight tested CYP98s from wheat have phenol meta-hydroxylase activity, with p-coumaroylshikimate being the primary substrate for all of these, as it is the case for CYP98s from sweet basil and Arabidopsis thaliana. While ancient duplication led to evolution of enzymes with different substrate preferences, most of recent duplicates underwent silencing via degenerative mutations. Cytochromes P450 (P450s or CYPs) are hemethiolate terminal monooxygenases that transfer one atom from molecular oxygen to XH bonds, where X may be the -C, -N, or S of a substrate, with a concomitant reduction in the remaining oxygen atom to water. Our results indicate that the unusually high frequency of gene duplication in the wheat CYP98 family is a direct or indirect result from ploidization. Cytochromes P450 Enzymes: General Features. Cytochrome P450 proteins, named for the absorption band at 450 nm of their carbon-monoxide- bound form, are one of the largest superfamilies of enzyme proteins. Comparison of the catalytic properties of the recombinant enzymes with those of CYP98s from other plant taxa was coupled to phylogenetic analyses. Eight coding sequences belonging to the CYP98 family reported to catalyze the 3-hydroxylation step in this pathway were isolated from Triticum aestivum (wheat) and expressed in yeast. They are highly diverse, with multiple copies of different families of these. In eukaryotes, they are usually bound to the endoplasmic reticulum or inner mitochondrial membranes. In prokaryotes, P450s are soluble proteins. Others, such as genes involved in the phenylpropanoid pathway have led to fewer duplication events. Cytochrome P450s are a group of detoxification enzymes found in all animals. In plants, chemical defense seems to be a major reason for P450 diversification. Within this superfamily some clans and families are heavily duplicated. A burst of evolutionary duplication upon land colonization seems to have led to the large superfamily of cytochromes P450 in higher plants.
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