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Amplite® Colorimetric L-Aspartate (Aspartic Acid) Assay Kit

Aspartate (or Aspartic acid) is a negatively charged, polar amino acid. Aspartate is involved in the control point of pyrimidine biosynthesis, in transamination reactions, interconversions with asparagine, in the metabolic pathway leading to AMP, in the urea cycle, and is a precursor to homoserine, threonine, isoleucine, and methionine. It is also involved in the malate aspartate shuttle. Amplite® Colorimetric Aspartate Assay Kit offers a sensitive colorimetric assay for quantifying aspartate in biological samples. Aspartate is converted to pyruvate that generates hydrogen peroxide through an enzyme coupled reaction. The amount of hydrogen peroxide generated by aspartate is monitored with Amplite® Red substrate for quantifying aspartate by in an absorbance microplate reader at 575 nm.

Example protocol

AT A GLANCE

Protocol Summary
  1. Prepare test samples (50 µL) along with serially diluted aspartate standards (50 µL)
  2. Add equal volume of working solution (50 µL)
  3. Incubate at 37 °C for 30 - 60 minutes

  4. Monitor absorbance increase at OD of 575±5 nm
Important Note

Thaw kit components at room temperature before use. To achieve the best results, it’s recommended to use the clear bottom plates.

PREPARATION OF STOCK SOLUTIONS

Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles

Aspartate standard solution (10 mM)

Add 100 µL of ddH2O into Aspartate Standard vial (Component E) to make 10 mM aspartate standard solution.

Amplite™ Red substrate stock solution

Add 50 µL of DMSO (Component F) into Amplite™ Red substrate (Component A) to make 200X Amplite™ Red substrate stock solution.
Note        Store unused 200X Amplite™ Red stock solution at -20 oC, avoid light and repeated freeze-thaw cycles.

PREPARATION OF STANDARD SOLUTIONS

For convenience, use the Serial Dilution Planner:
https://www.aatbio.com/tools/serial-dilution/13828

Aspartate standard
Add 32 µL of 10 mM aspartate standard into 368 µL of 1X PBS buffer to get 800 µM aspartate solution (ASP7). Then perform 1:2 serial dilutions in 1X PBS buffer to get serially diluted aspartate standards (ASP6 - ASP1).

PREPARATION OF WORKING SOLUTION

Conversion Mix solution (100X)

Add 50 µL of ddH2O into Conversion Mix (Component D) to make 100X Conversion Mix solution.

Amplite Red™ working solution

Add 5 mL Assay Buffer (Component C) into one Enzyme Mix 1 bottle (Component B1) and mix well. Add 100 μL of ddH2O into one Enzyme Mix 2 vial (Component B2) and mix well. Transfer entire vial (100 μL) of Enzyme Mix 2, 25 μL of 200X Amplite™ Red substrate stock solution, and 50 μL of 100X Conversion Mix solution into the Enzyme Mix 1 bottle and mix well.
Note        The working solution is not stable, use it promptly and avoid direct exposure to light. 

SAMPLE EXPERIMENTAL PROTOCOL

Table 1. Layout of aspartate standards and test samples in a clear bottom 96-well microplate. ASP= Aspartate Standard (ASP1 - ASP7, 12.5 to 100 µM), BL=Blank Control (1×PBS buffer), TS=Test Sample.

BLBLTSTS
ASP1ASP1......
ASP2ASP2......
ASP3ASP3
ASP4ASP4
ASP5ASP5
ASP6ASP6
ASP7ASP7

Table 2. Reagent composition for each well.

WellVolumeReagent
ASP1-ASP750 µL

Serial Dilution (12.5 to 100 µM)

BL50 µL1X PBS Buffer
TS50 µLTest Sample
  1. Prepare aspartate standards (ASP), blank control (BL) and test samples (TS) according to the layout provided in Tables 1 and 2. For a 384-well plate, use 25 µL of reagent per well instead of 50 µL.
  2. Add 50 µL of Amplite™ Red working solution to each well of aspartate standard, blank control, and test samples to make the total aspartate assay volume of 100 µL/well. For a 384-well plate, add 25 µL of Amplite™ Red working solution into each well instead, for a total volume of 50 µL/well. Note: Run the aspartate assay at pH 6.5 to 7.0.
  3. Incubate the reaction mixture at 37 °C for 30 - 60 minutes.

  4. Monitor the absorbance increase with an absorbance plate reader with path check at OD of 575 nm.

References

View all 20 references: Citation Explorer
A systematic and mechanistic evaluation of aspartic acid as filler for directly compressed tablets containing trimethoprim and trimethoprim aspartate
Authors: ElShaer A, Hanson P, Mohammed AR.
Journal: Eur J Pharm Biopharm (2013): 468
Enzymatic assay for D-aspartic acid using D-aspartate oxidase and oxaloacetate decarboxylase
Authors: Kato S, Ikuta T, Hemmi H, Takahashi S, Kera Y, Yoshimura T.
Journal: Biosci Biotechnol Biochem (2012): 2150
Distribution of free D-aspartic acid and D-aspartate oxidase in frog Rana esculenta tissues
Authors: Di Giovanni M, Burrone L, Chieffi Baccari G, Topo E, Santillo A.
Journal: J Exp Zool A Ecol Genet Physiol (2010): 137
Thyroid hormones and D-aspartic acid, D-aspartate oxidase, D-aspartate racemase, H2O2, and ROS in rats and mice
Authors: Topo E, Fisher G, Sorricelli A, Errico F, Usiello A, D'Aniello A.
Journal: Chem Biodivers (2010): 1467
Aslfm, the D-aspartate ligase responsible for the addition of D-aspartic acid onto the peptidoglycan precursor of Enterococcus faecium
Authors: Bellais S, Arthur M, Dubost L, Hugonnet JE, Gutmann L, van Heijenoort J, Legr and R, Brouard JP, Rice L, Mainardi JL.
Journal: J Biol Chem (2006): 11586
Page updated on November 21, 2024

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Storage, safety and handling

H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
UNSPSC12352200

Platform

Absorbance microplate reader

Absorbance575 ± 5 nm
Recommended plateClear bottom
Instrument specification(s)Path check

Components

Aspartate dose response was measured with Amplite® Colorimetric Aspartate Assay Kit on a white clear bottom 96-well plate using a SpectraMax microplate reader with Path check ON (Molecular Devices).
Aspartate dose response was measured with Amplite® Colorimetric Aspartate Assay Kit on a white clear bottom 96-well plate using a SpectraMax microplate reader with Path check ON (Molecular Devices).
Aspartate dose response was measured with Amplite® Colorimetric Aspartate Assay Kit on a white clear bottom 96-well plate using a SpectraMax microplate reader with Path check ON (Molecular Devices).