Main content area

Carboxyarabinitol 1-phosphate phosphatase from leaves of Phaseolus vulgaris and other species

Charlet, T., Moore, B.d., Seemann, J.R.
Plant & cell physiology 1997 v.38 no.5 pp. 511-517
Phaseolus vulgaris, Beta vulgaris, Helianthus annuus, Solanum lycopersicum var. lycopersicum, Panicum maximum, Triticum aestivum, Arabidopsis thaliana, Spinacia oleracea, Solanum tuberosum, leaves, protein composition, arabinitol, metabolism, phosphoric monoester hydrolases, purification, enzyme activity, physicochemical properties, chemical structure, photosynthesis, ribulose-bisphosphate carboxylase, phosphates, binding sites, Alocasia macrorrhizos
Carboxyarabinitol 1-phosphate (CA1P) phosphatase activity occurred in leaves of 10 species examined, with the highest activity in leaves of Phaseolus vulgaris. Enzyme was purified from P. vulgaris 1,580-fold to a final specific activity of 6.1 micromoles min-1 (mg protein)-1. Structural characteristics of positive effectors and substrate analogs for the CA1P phosphatase reaction were examined. Positive effectors were compounds that contained one phosphate group in close proximity to a second phosphate or a carboxyl group (e.g. 2-phosphoglycolate, pyrophosphate, 3-phosphoglycerate, and carboxyethylphosphonic acid). Many of the activators are structurally quite similar to CA1P, but were not used as substrates. In addition to the natural substrate CA1P, carboxypentitol and carboxyhexitol bisphosphates were shown to be good substrates (e.g. carboxyarabinitol bisphosphate and carboxymannitol bisphosphate). A substrate arabinitol configuration (R) was preferred at C-2, and reactivity was lost when a hydroxymethyl group was substituted for the carboxyl group. Despite structural similarities to positive effectors, none of the tested reaction substrates could activate the enzyme.