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DTPA

From Bioblast

DTPA (Diethylentriamin-N,N,N',N,N-pentaacetic acid, pentetic acid,[[(Carboxymethyl)imino]bis(ethylenenitrilo)]-tetra-acetic acid) is a polyaminopolycarboxylic acid (like EDTA) chelator of metal cations. DTPA wraps around a metal ion by forming up to eight bonds, beceuase each COO- group and and N-center serves a center for chelation. With transition metals the number of bounds is less than eight. The compound is not cell membrane permeable. In general, it chelates multivalent ions stronger than EDTA.

Description

  • CAS: 67-43-6
  • Source: EHRENSTORFER GmBH (EHERE13095000) or Sigma Aldrich (D-1133).
  • FW: 393.35
  • Chemical formula: C2H2O2
  • Solubility: It is soluble in water (4,8 g/l at 25 °C), but not readily soluble in ethanol or apolar solvents.
  • Stability constant: see: [1]:
Metal DTPA EDTA
Ca(II) 10.74 10.96
Mg(II) 9.3 8.69
Fe(II) 16.5 14.3
Fe(III) 28.6 25.1
Mn(II) 15.6 14.04
Zn(II) 18.75 16.5

Application in HRFR

Fluorometry:
  • In Amplex ultrared assay systems with HRP, there is a spontaneous increase in the ultoroxred fluorescence signal over the experimental time without any biological sample. This high background flux can be related to iron contamination. We have done a set of experiments, where we added DTPA as an iron-chelator into the O2k-chamber during AmR measurements. As a matter of fact, DTPA significantly reduced the high chemical background flux in Mir05 without effecting the respiration.
  • Administration of DTPA into the O2k-chamber is recommended before all other chemicals, because the iron chelation of the compound is time-dependent; it takes 10-15 min.
Preparation of the 5 mM stock solution of DTPA:
  1. Weigh 1.967 mg of DTPA in a 2 ml glass vial.
  2. Dissolve in 500 ul ddH2O and add 6 ul of 5M KOH to set the pH.
  3. Heat up the solution up to 33 °C.
  4. Add 2 ul 5M KOH to adjust the pH~7.
  5. Add 500 ul ddH2O to get 5 mM stock solution.
  6. The solution has to be prepared in glass vials, but after then it can be stored in Eppendorf tubes at -20 °C.
O2k manual titrations:
  • Final concentration in O2k-chamber: 15 µM
  • Stock solution: 5 mM
  • Titration volume: 6 ul