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EGTA tetrasodium salt *CAS 13368-13-3*

EGTA (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) is a water-soluble and cell-impermeable calcium chelator. It has high selectivity to calcium. Compared to EDTA, EGTA has a lower affinity for magnesium, making it more selective for calcium ions. It is useful in buffer solutions that resemble the environment in living cells where calcium ions are usually at least a thousand fold less concentrated than magnesium. The pKa for binding of calcium ions by tetrabasic EGTA is 11.00, but the protonated forms do not significantly contribute to binding, so at pH 7, the apparent pKa becomes 6.91.

Example protocol

AT A GLANCE

Important

Expiration date is 12 months from the date of receipt.

SAMPLE EXPERIMENTAL PROTOCOL

Sample Protocol for Calcium Measurement:

Titrate the concentration of free Ca2+ in solution by mixing different amounts of K2EGTA and CaEGTA. The reactions of these solutions with Fluo-3, Fluo 4, Fluo-8, Cal-520, or Calbryte 520 dye should be at room temperature, pH 7.2 and 100 mM KCl. Under these conditions, the Kd for EGTA is 150 nM. Measure the Fluo-3, Fluo 4, Fluo-8, Cal-520, or Calbryte 520 fluorescence intensity with a fluorescence microplate reader at Ex/Em = 490/525 nm.

  1. Mix the relative volumes of K2EGTA (Cat.# 21008) and CaEGTA according to the following table.

Sample #

Volume K2EGTA, uL

Volume CaEGTA, uL

Calculated free Ca2+, uM

RFU

zero (blank)

1000

0

0

0

1

900

100

  

2

800

200

  

3

700

300

  

4

600

400

  

5

500

500

  

6

400

600

  

7

300

700

  

8

200

800

  

9

100

900

  

 

  1. Calculate the concentration of free Ca2+ in each solution using the following formula:

[Ca2+]free = KdEGTA x {[CaEGTA]/[K2EGTA]} (Note: the Kd of EGTA is 150 nM).

  1. Add 1 uL of 1 mM Fluo-3, Fluo 4, Fluo-8, Cal-520, or Calbryte 520 into each solution including the blank.
  1. Read the fluorescence intensity of each solution with a fluorescent microplate reader at Ex/Em = 490/525 nm.

Calculators

Common stock solution preparation

Table 1. Volume of Water needed to reconstitute specific mass of EGTA tetrasodium salt *CAS 13368-13-3* to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM213.547 µL1.068 mL2.135 mL10.677 mL21.355 mL
5 mM42.709 µL213.547 µL427.095 µL2.135 mL4.271 mL
10 mM21.355 µL106.774 µL213.547 µL1.068 mL2.135 mL

Molarity calculator

Enter any two values (mass, volume, concentration) to calculate the third.

Mass (Calculate)Molecular weightVolume (Calculate)Concentration (Calculate)Moles
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Citations

View all 2 citations: Citation Explorer
Distortion of the Actin A-Triad Results in Contractile Disinhibition and Cardiomyopathy
Authors: Viswanathan, Meera C and Schmidt, William and Rynkiewicz, Michael J and Agarwal, Karuna and Gao, Jian and Katz, Joseph and Lehman, William and Cammarato, Anthony
Journal: Cell Reports (2017): 2612--2625
Routes of Ca2+ Shuttling during Ca2+ Oscillations FOCUS ON THE ROLE OF MITOCHONDRIAL Ca2+ HANDLING AND CYTOSOLIC Ca2+ BUFFERS
Authors: Pecze, László and Blum, Walter and Schwaller, Beat
Journal: Journal of Biological Chemistry (2015): 28214--28230

References

View all 77 references: Citation Explorer
Tuning caged calcium: photolabile analogues of EGTA with improved optical and chelation properties
Authors: Ellis-Davies GC, Barsotti RJ.
Journal: Cell Calcium (2006): 75
Catalytic superoxide scavenging by metal complexes of the calcium chelator EGTA and contrast agent EHPG
Authors: Fisher AE, Hague TA, Clarke CL, Naughton DP.
Journal: Biochem Biophys Res Commun (2004): 163
Voltage-activated calcium signals in myotubes loaded with high concentrations of EGTA
Authors: Schuhmeier RP, Dietze B, Ursu D, Lehmann-Horn F, Melzer W.
Journal: Biophys J (2003): 1065
Gravicurvature loss, changes in ultrastructure and calcium balance of pea root statocytes treated with EGTA
Authors: Belyavskaya NA., undefined
Journal: J Gravit Physiol (2001): P33
L-type calcium channel blockers and EGTA enhance superoxide production in cardiac fibroblasts
Authors: Shivakumar K, Kumaran C.
Journal: J Mol Cell Cardiol (2001): 373
Page updated on November 3, 2024

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Physical properties

Molecular weight

468.28

Solvent

Water

Storage, safety and handling

H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22

Storage

Freeze (< -15 °C); Minimize light exposure
UNSPSC12352200

CAS

13368-13-3
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