Phosphorus-31, sup 15 N, and sup 13 C NMR of glyphosate: Comparison of pH titrations to the herbicidal dead-end complex with 5-enolpyruvoylshikimate-3-phosphate synthase

Journal Article · Tue May 02 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00435a035· OSTI ID:5434898

Castellino, S; Leo, G C; Sammons, R D; Sikorski, J A ^[1]

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1. Monsanto Agricultural Company, St. Louis, MO (USA)

The herbicidal dead-end ternary complex (E{sup S3P}{sub Glyph}) of glyphosate (N-(phosphonomethyl)glycine) with 5-enolpyruvoylshikimate-3-phosphate synthase (EPSPS) and the substrate shikimate 3-phosphate (S3P) has been characterized by {sup 31}P, {sup 15}N, and {sup 13}C NMR. The NMR spectra of EPSPS-bound glyphosate show unique chemical shifts ({delta}) for each of the three nuclei. By {sup 31}P NMR, glyphosate in the dead-end complex is a distinct species 3.5 ppm downfield from free glyphosate. The {sup 13}C signal of glyphosate in the dead-end complex is shifted 4 ppm downfield from that of free glyphosate. The {sup 15}N signal for glyphosate (99%) in the dead-end complex is 5 ppm further downfield than that of any free zwitterionic species and 10 ppm downfield from that of the average free species at pH 10.1. The structures of each ionic state of glyphosate are modeled with force field calculations by using MacroModel. A correlation is made for the {sup 31}P {delta} and the C-P-O bond angle, and the {sup 13}C and {sup 15}N {delta} values are postulated to be related to C-C-O and C-N-C bond angles, respectively. The downfield {sup 31}P chemical shift perturbation for S3P in the EPSPS binary complex is consistent with ionization of the 3-phosphate of S3P upon binding. Comparison with the S3P {sup 31}P {delta} vs pH titration curve specifies predominantly the dianion of the 3-phosphate in the E{sup S3P} binary complex, while the E{sup S3P}{sub Glyph} complex indicates net protonation at the 3-phosphate. Chemical shift perturbations of this latter type may be explained by changes in the O-P-O bond angle.

• OSTI ID: 5434898
• Journal Information: Biochemistry; (USA), Vol. 28:9; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
HERBICIDES
NUCLEAR MAGNETIC RESONANCE
TRANSFERASES
BIOCHEMICAL REACTION KINETICS
BOND ANGLE
CARBON 13
CHEMICAL BONDS
CHEMICAL SHIFT
GLYCINE
NITROGEN 15
PH VALUE
PHOSPHORUS 31
AMINO ACIDS
CARBON ISOTOPES
CARBOXYLIC ACIDS
ENZYMES
EVEN-ODD NUCLEI
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PESTICIDES
PHOSPHORUS ISOTOPES
REACTION KINETICS
RESONANCE
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques