Product ManualTyrosine Assay Kit
Catalog Number
MET-5073

100 assays

FOR RESEARCH USE ONLY
Not for use in diagnostic procedures

Introduction
Tyrosine (also known as 4-hydroxyphenylalanine) is one of the 20 amino acids that serve as building
blocks to form peptides and proteins. As a part of proteins, tyrosine plays a role in signal transduction
since phosphate groups are transferred to the hydroxyl group of the phenolic side chain of tyrosine byreceptor tyrosine kinases, resulting in a change in activity of the target phosphorylated protein. Inaddition, a tyrosine side chain contributes to the process of photosynthesis. In photosystem II ofchloroplasts, tyrosine residue 161 of P680 acts as an electron donor to reduce oxidized chlorophyll. Inplants and lower microorganisms, tyrosine is synthesized from the precursor prephenate (the latter also
an intermediate to synthesis of shikimate). Prephenate is decarboxylated to create phydroxyphenylpyruvate, which is then transaminated to yield tyrosine and α-ketoglutarate. In animals,
tyrosine is created from dietary sources of the essential amino acid phenylalanine. Phenylalanine isconverted to tyrosine by the enzyme phenylalanine hydroxylase.
Tyrosine is a neurotransmitter precursor and increases the levels of plasma neurotransmitters such as
norepinephrine and dopamine. A number of studies have found tyrosine to reduce stress underconditions of sleep deprivation, prolonged work, cold, or fatigue, and includes reductions in stresshormone levels, and stress-induced weight loss. In addition, improvements in cognitive and physicalperformance have been observed in humans.
Cell Biolabs’ Tyrosine Assay Kit is a simple colorimetric assay that measures the total amount of freetyrosine present in foods or biological samples in a 96-well microtiter plate format. The Tyrosine
Assay Kit can also detect L-DOPA, γ-L-glutaminyl-3,4-hydroxybenzene (GHB), and γ-glutaminyl-3,4dihydroxybenzene (GDHB). Tyrosine is enzymatically oxidized to a colorimetric intermediate which isthen measured with a standard 96-well spectrophotometric plate reader. Samples are compared to aknown concentration of tyrosine standard within the 96-well microtiter plate format. Each kit provides
sufficient reagents to perform up to 100 assays, including blanks, tyrosine standards, and unknown
samples. Sample tyrosine concentrations are determined by comparison with a known tyrosine
standard. The kit has a detection sensitivity limit of 15.6 µM tyrosine.

Related Products
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MET-5054: L-Amino Acid Assay Kit (Colorimetric)
MET-5056: Branched Chain Amino Acid Assay Kit
MET-5070: Glycine Assay Kit
STA-674: Glutamate Assay Kit
MET-5071: Taurine Assay Kit

Kit Components
1. Tyrosine Standard (Part No. 50731C): One 100 µL vial at 100 mM.
2. 10X Assay Buffer (Part No. 50732A): One 25 mL bottle.
3. 10X Enzyme (Part No. 50733D): One 500 µL vial.

Materials Not Supplied
1. Distilled or deionized water2

2. 1X PBS
3. Standard 96-well black microtiter plate and/or cell culture microplate

StorageUpon receipt, store the Tyrosine Standard and 10X Enzyme at -20ºC. Store the 10X Assay Buffer atroom temperature.

Preparation of Reagents•

1X Assay Buffer: Dilute the 10X Assay Buffer to 1X with deionized water. Stir to homogeneity.
Store at room temperature.
• Reaction Mix: Prepare a Reaction Mix by diluting the 10X Enzyme 1:10 in 1X Assay Buffer. Forexample, add 100 μL to 900 μL of 1X Assay Buffer for a total of 1 mL. This Reaction Mix volumeis enough for 20 assays. The Reaction Mix is stable for 1 day at 4ºC.
Note: Prepare only enough for immediate use by scaling the above example proportionally.

Preparation of Samples••••

Tissue lysates: Sonicate or homogenize tissue sample in cold PBS or 1X Assay Buffer andcentrifuge at 10,000 x g for 10 minutes at 4°C. Perform dilutions in 1X Assay Buffer.
Cell lysates: Resuspend cells at 1-2 x 106 cells/mL in PBS or 1X Assay Buffer. Homogenize orsonicate the cells on ice. Centrifuge to remove debris. Cell lysates may be assayed undiluted or
diluted as necessary in 1X Assay Buffer.
Urine: Deproteinate the sample by running it through a centrifugal filter unit (e.g., Amicon Ultra 0.5
mL 10K Cat. No. UFC501024) and collecting the flow through. To remove insoluble particles,
centrifuge at 10,000 rpm for 5 min. The supernatant may be assayed undiluted or diluted asnecessary in 1X Assay Buffer.
Serum or Plasma: Deproteinate the sample by running it through a centrifugal filter unit (e.g.,Amicon Ultra 0.5 mL 10K Cat. No. UFC501024) and collecting the flow through. To remove
insoluble particles, centrifuge at 10,000 rpm for 5 min. The supernatant may be assayed undiluted
or diluted as necessary in 1X Assay Buffer.

Note: All samples should be assayed immediately or stored at -80°C for up to 1-2 months. Run proper
controls as necessary. Optimal experimental conditions for samples must be determined by theinvestigator. Always run a standard curve with samples.

3Preparation of Standard Curve
Prepare fresh Tyrosine Standards before use by diluting in 1X Assay Buffer according to Table 2below.
Standard Tubes
12345678100 mM Tyrosine Solution (µL)
5250 of Tube #1
250 of Tube #2
250 of Tube #3
250 of Tube #4
250 of Tube #5
250 of Tube #60

1X Assay Buffer (µL) Tyrosine (µM)
495
1000
250
500
250
250
250
125
250
62.5
250
31.3
250
15.6250
0Table 2. Preparation of Tyrosine Standards.

Assay Protocol
1. Prepare and mix all reagents thoroughly before use. Each sample, including unknowns andstandards, should be assayed in duplicate or triplicate.
2. Add 50 µL of each Tyrosine Standard or unknown sample into wells of a 96-well microtiter plate.
3. Add 50 µL of Reaction Mix to each well. Mix the well contents thoroughly and incubate for 10
minutes at room temperature on an orbital shaker.
4. Read the plate at 490 nm using a microplate spectrophotometer.

Example of Results
The following figures demonstrate typical Tyrosine Assay Kit results. One should use the data below
for reference only. This data should not be used to interpret or calculate actual sample results.

Figure 2: Tyrosine Standard Curve.

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Figure 3: Tyrosine Detection in Normal Human Saliva, Urine or Serum. Tyrosine was detected in humansamples. Samples were deproteinated and tested undiluted according to the Assay Protocol.

References
1.
2.
3.
4.

Rasmussen DD, Ishizuka B, Quigley ME, Yen SS (1983). J. Clin. Endocrinol. Metab. 57: 760–763
Leathwood PD, Pollet P (1982). J. Psych. Res. 17: 147–154.
Deijen JB, Orlebeke JF (1994). Brain Res. Bull. 33: 319–323.
Lieberman HR, Corkin S, Spring BJ, Wurtman RJ, Growdon JH (1985). Am J Clin Nutr. 42: 366–370.
5. Hao S, Avraham Y, Bonne O, Berry EM (2001). Pharmacol. Biochem. Behav. 68: 273–281.
6. Magill RA, Waters WF, Bray GA, Volaufova J, Smith SR, Lieberman HR, McNevin N, Ryan DH(2003). Nutr. Neurosci. 6: 237–246.
7. Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DL (1995). Aviat. Space
Envir. Med. 66: 313–319.
8. Reinstein DK, Lehnert H, Wurtman RJ (1985). Life Sci. 37: 2157–2163.
9. Deijen JB, Wientjes CJ, Vullinghs HF, Cloin PA, Langefeld JJ (1999). Brain Res. Bull. 48: 203–209.
10. Mahoney CR, Castellani J, Kramer FM, Young A, Lieberman HR (2007). Physiol. Behav. 92: 575–582.

Recent Product Citations
1. Loza-Valdes, A. et al. (2021). A phosphoproteomic approach reveals that PKD3 controls PKAmediated glucose and tyrosine metabolism. Life Sci Alliance. 4(8):e202000863. doi:
10.26508/lsa.202000863.
2. Yang, Y. et al. (2019). A laser-engraved wearable sensor for sensitive detection of uric acid andtyrosine in sweat. Nat Biotechnol. doi: 10.1038/s41587-019-0321-x.

5Warranty
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exclusive remedy for breach of this warranty shall be, at the option of CELL BIOLABS, to repair or replace the products. Inno event shall CELL BIOLABS be liable for any proximate, incidental or consequential damages in connection with theproducts.

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