Human ACE ELISA Kit

Angiotensin-converting enzyme (ACE) is a zinc-containing dipeptidyl carboxypeptidase widely distributed in mammalian tissues and is thought to play a critical role in blood pressure regulation. The predicted protein is identical, from residue 37 to its C terminus, to the second half or C-terminal domain of the endothelial ACE sequence. The protein sequence inferred consists of a 732-residue preprotein including a 31-residue signal peptide. The mature polypeptide has a molecular weight of 80,073. Although ACE has been studied primarily in the context of its role in blood pressure regulation, this widely distributed enzyme has many other physiological functions. The ACE gene encodes two isozymes. The somatic isozyme is expressed in many tissues, including vascular endothelial cells, renal epithelial cells, and testicular Leydig cells, whereas the testicular or germinal angiotensin-converting enzyme is expressed only in sperm. The standard product used in this kit is recombinant human ACE, consisting of 30-1261 amino acids with the molecular mass of 120KDa. The lead time for delivery is one week.

Sku #Product NameProduct SizePriceQTY
2900010015 Human ACE ELISA Kit 1 Plate 1 Plate $510.00 USD
 

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For quantitative detection of human ACE in cell culture supernates, serum, plasma(heparin) and saliva.

Typical Data Obtained from Human ACE

(TMB reaction incubate at 37°C for 20 min)
Concentration(pg/ml)
0
156
312
625
1250
2500
5000
10,000
O.D
0.059
0.102
0.165
0.270
0.490
1.043
1.732
2.243

Typical Human ACE ELISA Kit Standard Curve

This standard curve was generated at Eton for demonstration purpose only. A standard curve must be run with each assay.
Range 156pg/ml-10,000pg/ml
Sensitivity < 5pg/ml
Specificity Natural and recombinant human ACE
Cross-reactivity No detectable cross-reactivity with other relevant proteins

Storage

Store at 4°C for 6 months, at -20°C for 12 months. Avoid multiple freeze-thaw cycles (Shipped with wet ice.)

Principle

Eton’s human ACE ELISA Kit was based on standard sandwich enzyme-linked immune-sorbent assay technology. A monoclonal antibody from mouse specific for ACE has been precoated onto 96-well plates. Standards( NSO,L30-L1261) and test samples are added to the wells, a biotinylated detection polyclonal antibody from goat specific for ACE is added subsequently and then followed by washing with PBS or TBS buffer. Avidin-Biotin-Peroxidase Complex was added and unbound conjugates were washed away with PBS or TBS buffer. HRP substrate TMB was used to visualize HRP enzymatic reaction. TMB was catalyzed by HRP to produce a blue color product that changed into yellow after adding acidic stop solution. The density of yellow is proportional to the human ACE amount of sample captured in plate.

Kit Components

Description
Quantity
96-well plate precoated with anti- human ACE antibody
1
Lyophilized recombinant human ACEstandard
10ng/tube×2
Biotinylated anti- human ACE antibody
130μl(dilution 1:100)
Avidin-Biotin-Peroxidase Complex (ABC)
130μl(dilution 1:100)
Sample diluent buffer
30 ml
Antibody diluent buffer
12ml
ABC diluent buffer
12ml
TMB color developing agent
10ml
TMB stop solution
10ml

Material Required But Not Provided

1. Microplate reader in standard size.
2. Automated plate washer.
3. Adjustable pipettes and pipette tips. Multichannel pipettes are recommended in the condition of large amount of samples in the detection.
4. Clean tubes and Eppendorf tubes.
5. Washing buffer (neutral PBS or TBS).
ØPreparation of 0.01M TBS: Add 1.2g Tris, 8.5g Nacl; 450μl of purified acetic acid or 700μl of concentrated hydrochloric acid to 1000ml H2O and adjust pH to 7.2-7.6. Finally, adjust the total volume to 1L.
ØPreparation of 0.01 M PBS: Add 8.5g sodium chloride, 1.4g Na2HPO4 and 0.2g NaH2PO4 to 1000ml distilled water and adjust pH to 7.2-7.6. Finally, adjust the total volume to 1L.

Notice for Application of Kit

1. To inspect the validity of experiment operation and the appropriateness of sample dilution proportion, pilot experiment using standards and a small number of samples is recommended.
2. The TMB Color Developing agent is colorless and transparent before using, contact us freely if it is not the case.
3. Before using the Kit, spin tubes and bring down all components to the bottom of tubes.
4. Duplicate well assay is recommended for both standard and sample testing.
5. Don’t let 96-well plate dry, for dry plate will inactivate active components on plate.
6. Don’t reuse tips and tubes to avoid cross contamination.
7. To avoid to use the reagents from different batches together.
8. In order to avoid marginal effect of plate incubation due to temperature difference (reaction may be stronger in the marginal wells), it is suggested that the diluted ABC and TMB solution will be pre-warmed in 37°C for 30 min before using.


Preparation

1. Sample Preparation and Storage
Store samples to be assayed within 24 hours at 2-8°C. For long-term storage, aliquot and freeze samples at -20°C. Avoid repeated freeze-thaw cycles.
Cell culture supernates: Remove particulates by centrifugation, assay immediately or aliquot and storesamples
at -20°C.
Serum: Allow the serum to clot in a serum separator tube (about 4 hours) at room temperature.Centrifuge at approximately 1000 X g for 15 min. Analyze the serum immediately or aliquot and store samples at -20°C.
Plasma: Collect plasma using heparin as an anticoagulant. Centrifuge for 15 min at 1500 x g within 30min of collection. Assay immediately or aliquot and store samples at -20°C.
Saliva: Collect saliva using a collection device without any protein binding or filtering capabilities such asa Salivette or aliquot and store samples at -20°C.

2. Sample Dilution Guideline

The user needs to estimate the concentration of the target protein in the sample and select a proper dilution factor so that the diluted target protein concentration falls near the middle of the linear regime in the standard curve. Dilute the sample using the provided diluent buffer. The following is a guideline for sample dilution. Several trials may be necessary in practice. The sample must be well mixed with the diluents buffer.
High target protein concentration (100-1000ng/ml). The working dilution is 1:100. i.e. Add 1μl sampleinto 99 μl sample diluent buffer.
Medium target protein concentration (10-100ng/ml). The working dilution is 1:10. i.e. Add 10μl sampleinto 90 μl sample diluent buffer.
Low target protein concentration (156-10,000pg/ml). The working dilution is 1:2. i.e. Add 50μl sampleto 50 μl sample diluent buffer.
Very Low target protein concentration (≤156pg/ml). No dilution necessary, or the working dilution is 1:2.

3. Reagent Preparation and Storage
A. Reconstitution of the human ACE standard: ACE standard solution should be prepared no more than 2 hours prior to the experiment. Two tubes of ACE standard (10ng per tube) are included in each kit. Use one tube for each experiment.
a. 10,000pg/ml of human ACE standard solution: Add 1ml sample diluent buffer into one tube, keep the tube at room temperature for 10 min and mix thoroughly.
b. 5000pg/ml →156pg/ml of human ACE standard solutions: Label 6 Eppendorf tubes with 5000pg/ml, 2500pg/ml, 1250pg/ml, 625pg/ml, 312pg/ml, 156pg/ml respectively. Aliquot 0.3ml of the sample diluent buffer into each tube. Add 0.3ml of the above 10,000pg/ml ACE standard solution into 1st tube and mix. Transfer 0.3ml from 1st tube to 2nd tube and mix. Transfer 0.3ml from 2nd tube to 3rd tube and mix, and so on.
Note: The standard solutions are best used within 2 hours. The 10ng/ml standard solution should be storedat 4°C for up to 12 hours, or at -20°C for up to 48 hours. Avoid repeated freeze-thaw cycles.
B. Preparation of biotinylated anti-human ACE antibody working solution: The solution should be prepared no more than 2 hours prior to the experiment.
a. The total volume should be: 0.1ml/well x (the number of wells). (Allowing 0.1-0.2 ml more than total volume)
b. Biotinylated anti-human ACE antibody should be diluted in 1:100 with the antibody diluent buffer and mixed thoroughly. (i.e. Add 1μl Biotinylated anti-human ACE antibody to 99μl antibody diluent buffer.)
C. Preparation of Avidin-Biotin-Peroxidase Complex (ABC) working solution: The solution should be prepared no
more than 1 hour prior to the experiment.
a. The total volume should be: 0.1ml/well x (the number of wells). (Allowing 0.1-0.2 ml more than total volume)
b. Avidin- Biotin-Peroxidase Complex (ABC) should be diluted in 1:100 with the ABC dilution buffer and mixed thoroughly. (i.e. Add 1μl ABC to 99μl ABC diluent buffer.)

Assay Procedure
The ABC working solution and TMB color developing agent must be kept warm at 37°C for 30 min before use. When diluting samples and reagents, they must be mixed completely and evenly. Standard ACE detection curve should be prepared for each experiment. The user will decide sample dilution fold by crude estimation of ACE amount in samples.
1. Aliquot 0.1ml per well of the 10,000pg/ml, 5000pg/ml, 2500pg/ml, 1250pg/ml, 625pg/ml, 313pg/ml, 156pg/ml human ACE standard solutions into the precoated 96-well plate. Add 0.1ml of the sample diluent buffer into the control well (Zero well). Add 0.1ml of each properly diluted sample of human cell culture supernatants, serum, plasma(heparin) or saliva to each empty well. See “Sample Dilution Guideline” above for details. We recommend that each human ACE standard solution and eachsample is measured in duplicate.
2. Seal the plate with the cover and incubate at 37°C for 90 min.
3. Remove the cover, discard plate content, and blot the plate onto paper towels or other absorbent material. Do NOT let the wells completely dry at any time.
4. Add 0.1ml of biotinylated anti-human ACE antibody working solution into each well and incubate the plate at 37°C for 60 min.
5. Wash plate 3 times with 0.01M TBS or 0.01M PBS, and each time let washing buffer stay in the wells for 1 min. Discard the washing buffer and blot the plate onto paper towels or other absorbent material. (Plate Washing Method: Discard the solution in the plate without touching the side walls. Blot the plate onto paper towels or other absorbent material. Soak each well with at least 0.3 ml PBS or TBS buffer for 1~2 minutes. Repeat this process two additional times for a total of THREE washes. Note: For automated washing, aspirate all wells and wash THREE times with PBS or TBS buffer, overfilling wells with PBS or TBS buffer. Blot the plate onto paper towels or other absorbent material.)
6. Add 0.1ml of prepared ABC working solution into each well and incubate the plate at 37°C for 30 min.
7. Wash plate 5 times with 0.01M TBS or 0.01M PBS, and each time let washing buffer stay in the wells for 1-2 min. Discard the washing buffer and blot the plate onto paper towels or other absorbent material. (See Step 5 for plate washing method).
8. Add 90μl of prepared TMB color developing agent into each well and incubate plate at 37°C in dark for
20-25 min (Note: For reference only, the optimal incubation time should be determined by end user. And the shades of blue can be seen in the wells with the four most concentrated human ACE standard solutions; the other wells show no obvious color).
9. Add 0.1ml of prepared TMB stop solution into each well. The color changes into yellow immediately.
10. Read the O.D. absorbance at 450nm in a microplate reader within 30 min after adding the stop solution.
For calculation, (the relative O.D.450) = (the O.D.450 of each well) – (the O.D.450 of Zero well). The standard curve can be plotted as the relative O.D.450 of each standard solution (Y) vs. the respective concentration of the standard solution (X). The human ACE concentration of the samples can be interpolated from the standard curve.
Note: if the samples measured were diluted, multiply the dilution factor to the concentrations from interpolation toobtain the concentration before dilution.

Summary
1. Add samples and standards and incubate the plate at 37°C for 90 min. Do not wash.
2. Add biotinylated antibodies and incubate the plate at 37°C for 60 min. Wash plate 3 times with 0.01M TBS.
3. Add ABC working solution and incubate the plate at 37°C for 30 min. Wash plate 5 times with 0.01M TBS.
4. Add TMB color developing agent and incubate the plate at 37°C in dark for 20-25 min.
5. Add TMB stop solution and read.

1. Ehlers, M. R. W.; Fox, E. A.; Strydom, D. J.; Riordan, J. F. Molecular cloning of human testicular angiotensin-converting enzyme: the testis isozyme is identical to the C-terminal half of endothelial angiotensin-converting enzyme. Proc. Nat. Acad. Sci. 86: 7741-7745, 1989.
2. Ramaraj, P.; Kessler, S. P.; Colmenares, C.; Sen, G. C. Selective restoration of male fertility in mice lacking angiotensin-converting enzymes by sperm-specific expression of the testicular isozyme. J. Clin. Invest. 102: 371-378, 1998.


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