2.0 2015-09-08 17:50:02 -0600 2016-09-13 16:35:43 -0600 ECMDB24198 M2MDB006315 2-aminoprop-2-enoate 2-Aminoprop-2-enoate is an intermediate of several pathways in E. coli. In D-serine degradation pathway, it is a product for the enzyme D-serine ammmonia-lyase which catalyzes the reaction D-serine → 2-aminoprop-2-enoate + H2O + H+. It is also products in pathways L-cysteine degradation II, L-methionine biosynthesis I, L-serine degradation and L-tryptophan degradation II (BioCyc compound: 2-AMINOACRYLATE). 2-Aminoprop-2-enoic acid 2-aminoprop-2-enoate α-aminoacrylate logp -0.37 ALOGPS logs 0.40 ALOGPS solubility 2.62e+02 g/l ALOGPS logp -2.9 ChemAxon pka_strongest_acidic 2.58 ChemAxon pka_strongest_basic 8.64 ChemAxon iupac 2-aminoprop-2-enoate ChemAxon polar_surface_area 66.15 ChemAxon refractivity 31.75 ChemAxon polarizability 7.32 ChemAxon rotatable_bond_count 1 ChemAxon acceptor_count 3 ChemAxon donor_count 1 ChemAxon physiological_charge 0 ChemAxon formal_charge -1 ChemAxon methionine biosynthesis The de novo biosynthesis of methionine is an energy-costly process involving inputs from several other pathways. The carbon skeleton of methionine is derived from aspartate. The sulfur is derived from cysteine which derives its sulfur from sulfate assimilation. The methyl group is derived from serine via one-carbon metabolism. Methionine is also converted to S-adenosyl-L-methionine, a methyl group donor, by the product of gene metK . The synthesis starts with a product of the lysine biosynthesis pathway, L-aspartate-semialdehyde. This compound is dehydrogenated by a NADPH aspartate kinase / homoserine dehydrogenase resulting in NADP and L-homoserine. Homoserine is activated by O-succinylation in a reaction catalyzed by MetA. The product O-succinyl-L-homoserine combines with cysteine to form cystathionine in a reaction catalyzed by MetB. Lyase cleavage of cystathionine by MetC forms homocysteine. This β-cystathionase activity can also be supplied by MalY as demonstrated in vivo by the ability of constitutive MalY expression to complement metC mutants auxotrophic for methionine . Homocysteine is subsequently methylated by either MetH or MetE to produce methionine. In E. coli MetH can function only in the presence of exogenously supplied vitamin B12 (cobalamin), which represses MetE expression. B12 is likely to be available in the gut. In the absence of exogenously supplied B12, MetE catalyzes this final step of de novo methionine biosynthesis. L-methionine is then transferred into the periplasmic space through a leucine efflux transporter. Under stressful conditions there is further regulation of the pathway enzymes. Under heat-shock conditions growth is slowed due to the thermal instability of MetA. Oxidative stress affects MetE which contains an oxidation-sensitive cysteine residue at position 645 near the active site. Oxidation of methionone itself can also occur although the cell contains methionine sufloxide reductases MsrA and MsrB to combat this. Weak organic acids also generate oxidative stress, with more complex effects. Sulfur limitation depletes homocysteine which serves as a coactivator for MetR activation of MetE expression. Due to the absence of this pathway in mammals, some of the bacterial biosynthetic enzymes are potential drug targets. In addition, although methionine is used as a food additive and a medication, its industrial scale production in microorganisms has not yet been achieved due to the complexity and strong regulation of its biosynthetic pathway. PW000814 Metabolic L-cysteine degradation The degradation of cysteine starts with L-cysteine reacting with l-cysteine desulfhydrase resulting in the release of a hydrogen sulfide, a hydrogen ion and a a 2-aminoprop-2-enoate. The latter compound in turn reacts spontaneously to form a 2-iminopropanoate. This compound in turn reacts spontaneously with water and a hydrogen ion resulting in the release of ammonium and pyruvate. PW002110 Metabolic Specdb::MsMs 26117 Specdb::MsMs 26118 Specdb::MsMs 26119 Specdb::MsMs 32675 Specdb::MsMs 32676 Specdb::MsMs 32677 Cystathionine beta-lyase metC P06721 METC_ECOLI metC http://ecmdb.ca/proteins/P06721.xml Tryptophanase P0A853 TNAA_ECOLI tnaA http://ecmdb.ca/proteins/P0A853.xml Protein malY P23256 MALY_ECOLI malY http://ecmdb.ca/proteins/P23256.xml L-Cystathionine > Hydrogen ion + Homocysteine + 2-aminoprop-2-enoate + Homocysteine PW_R002891 L-Cysteine > Hydrogen sulfide + Hydrogen ion + 2-aminoprop-2-enoate PW_R006145