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Results 1 - 4 of 4
EC Number General Information Commentary Reference
Display the reaction diagram Show all sequences the enzyme belongs to the CrtI family of enzymes, analysis of the phylogenetic tree of a subset of phytoene desaturases from the CrtI family, overview. Recombinant expression of eight codon optimized CrtI enzymes from different clades in a bacterial system reveals that three CrtI enzymes can catalyse up to six desaturations, forming tetradehydrolycopene. Existence of characteristic patterns of desaturated molecules associated with various CrtI clades. Variations in the reaction rates and binding constants can explain the various carotene patterns observed. Relationship between genetic and functional evolution of certain CrtI enzymes, overview -, 759253
Display the reaction diagram Show all sequences carotenoid biosynthesis starts with the symmetrical condensation of two geranylgeranyl diphosphate molecules, forming phytoene. A series of successive desaturation reactions convert phytoene into phytofluene, zeta-carotene, neurosporene, lycopene. These desaturation reactions can be accomplished by a single enzyme (poly-trans pathway) or through a cascade of different enzymes (poly-cis pathway). In algae and plants, four different enzymes are necessary to form the final product (all-trans-lycopene). The phytoene and the zeta-carotene desaturases (PDS and ZDS, respectively) add double bonds in the cis-conformation. ZISO (zeta-carotene isomerase) and CRTISO (prolycopene isomerase) convert the cis-carotenes into di-cis-zeta-carotene and all-trans-lycopene, respectively. By contrast to other phytoene desaturases, CrtI are versatile enzymes classified into four enzymatic subgroups (EC, EC, EC, and EC based on the last product they presumably produce (from zeta-carotene to didehydrolycopene). Carotene diversity can be further expanded in later steps with the addition of one or two rings by lycopene cyclases, thereby producing an extensive variety of symmetrical or asymmetrical cyclised carotenes, such as beta-zeacarotene, dehydro-beta-carotene, gamma-carotene, beta-carotene, and the fungi-specific torulene. When expressed in heterologous hosts, CrtI enzymes exhibit distinct desaturation patterns, CrtI enzyme activities may depend on the experimental conditions and thus be inconsistent with the patterns generated in the natural host. Pantoea ananatis CrtI produces lycopene in vivo, but also tetradehydrolycopene in vitro -, 759253
Display the reaction diagram Show all sequences comparison of the natural evolution and kinetic properties of selected CrtI enzymes expressed and assayed under standardised conditions. Potentially all CrtI enzymes can catalyse desaturation reactions that progress beyond the already observed end-products and the pattern of products formed originates from variations in the reaction rates rather than affinity constants -, 759253
Display the reaction diagram Show all sequences function the expression product of crtI is essential for phytoene conversion to lycopene and 3,4-didehydrolycopene -, 742615
Results 1 - 4 of 4