Data collection

R factor = 0.090; wR factor = 0.279; data-to-parameter ratio = 12.2. The title compound, C5H9NO4H2O, is an isomer of the -amino acid glutamic acid that crystallizes from water in its zwitterionic form as a monohydrate. It is not one of the 20 proteinogenic -amino acids that are used in living systems and differs from the natural amino acids in that it has an -methyl group rather than an -H atom. In the crystal, an O— H O hydrogen bond is present between the acid and water molecules while extensive N—H O and O—H O hydrogen bonds link the components into a three-dimensional array. Related literature For the eighty amino acids that have been detected in meteorites or comets, see: Pizzarello et al. (2006); Glavin & Dworkin, (2009); Burton et al. (2012). For the role that crys-tallization plays in chiral separation, see: Blackmond & Klussmann (2007); Blackmond et al. (2008). For the role of the H atom on the -C atom in enhancing the rate of racemiza-tion, see: Yamada et al. (1983). For the mechanism of race-mization of amino acids lacking an -H atom, see: Pizzarello & Groy (2011). For the role that crystallization can play in the enrichment of l isovaline and its structure, see: Glavin & Dworkin (2009); Butcher et al. (2013). For normal bond lengths and angles, see: Orpen (1993). For the number of -methyl amino acids that have been observed with l-enanti-omeric excesses up to 20 % that are not believed to be the result of contamination, see: Pizzarello & Cronin (2000); Glavin & Dworkin (2009); Glavin et al. (2011, 2012); Burton et al. (2013)