Structure of tris(cyclohexylammonium) phosphoenolpyruvate monohydrate and crystal chemistry of phosphoenolpyruvates

Abstract

The crystal structure of (C6H11NH3+)3. Pep3-.H2O, where Pep3- = (O-)2P(O)-O-C(CH2)-CO2-, is reported and the systematic structural variations among 19 crystallographic occurrences of H3Pep, H2Pep-, HPep2- and Pep3- species, which are important phosphate donors in the ATP cycle of bioenergetics, are reviewed. Tris(cyclohexylammonium) phosphoenolpyruvate monohydrate, (C6H11NH3+)3.-[O3POC(CH2)CO2]3-.H2O, M(r) = 483.6, m.p. 418-420K; T = 296(1)K; orthorhombic, P2(1)2(1)2(1); a = 16.7042(5), b = 24.4881 (6), c = 6.38910 (10) A; V = 2613.49(11) A3, Z = 4, Dx = 1.23, Dm = 1.22 mg mm-3, mu = 0.14 mm-1 for lambda(MoK alpha) = 0.7107 A; F(000) = 1056 e; R(magnitude of F) = 0.0608 for 6056 hkl and hkl data with (sin theta)/lambda < or = 0.65 A-1.

Theoretical Studies of Dissociative Phosphoryl Transfer in Interconversion of Phosphoenolpyruvate to Phosphonopyruvate: Solvent Effects, Thio Effects, and Implications for Enzymatic Reactions

“…Both HF and B3LYP calculations predict that the enol and carboxylate groups are twisted out of planarity, with an O 1 −C 1 −C 2 −O 3 dihedral angle of 144.1° and 156.1°, respectively. The nonplanarity of the enolpyruvyl group has been observed in X-ray diffraction studies, and the dihedral angle depends sensitively on the protonation state and the environment. − To understand the conformational energetics for PEP, we have computed the minimal energy path along the O 1 −C 1 −C 2 −O 3 dihedral angle. As shown in Figure , the rotation along the C 1 −C 2 bond is quite free.…”