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Characterization of the methylenediphosphonate transport system in Arthrobacter sp. GLP‐1 using the novel tritium‐labelled derivative
Author(s) -
Yakovleva G.M.,
Blackburn G.M.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81505-t
Subject(s) - pyrophosphate , tritium , arthrobacter , chemistry , kinetics , phosphate , biochemistry , chromatography , enzyme , physics , quantum mechanics , nuclear physics
The novel tritium‐labelled derivative of methylenediphosphonate (MDP) was used in uptake studies of Arthrobacter sp. GLP‐1 capable of utilizing a wide range of organophosphonates as its sole source of phosphorus. The MDP uptake was greatly stimulated upon phosphate deprivation. The uptake obeys Michaelis‐Menten kinetics with respective K m and V max values of 33 μM and 0.3 nmol·min −1 ·mg −1 fr.wt. Glyphosate and pyrophosphate were competitive inhibitors of MDP uptake. The effect of orthophosphate was more complex than a mere inhibition of MDP uptake since activation occurred at low concentrations. The uptake of MDP by Arthrobacter sp. strain GLP‐1 appears to be mediated by a transport system different from the glyphosate uptake system operating in the same cells. The driving force for MDP uptake by Arthrobacter sp. GLP‐1 may be a proton gradient across the cell membrane.