L-Tyrosine
[CAS# 60-18-4]

Identification

• Classification: Biochemical >> Common amino acids and protein drugs
• Name: L-Tyrosine
• Synonyms: 2-Amino-3-(4-hydroxyphenyl)-propanoic acid; 3-(4-Hydroxyphenyl)-L-alanine; Tyr
• Molecular Formula: C₉H₁₁NO₃
• Molecular Weight: 181.19
• Protein Sequence: Y
• CAS Registry Number: 60-18-4
• EC Number: 200-460-4
• FEMA: 3736
• SMILES: C1=CC(=CC=C1C[C@@H](C(=O)O)N)O

Properties

• Solubility: 0.45 g/L (water, 25 °C), 25 g/mL (1 M HCl) (Expl.)
• Density: 1.3±0.1 g/cm³, Calc.^*, 1.456 g/mL (Expl.)
• Melting point: 300 °C (decomp.)
• Index of Refraction: 1.614, Calc.^*
• alpha: -11.65 ° (c=5,DIL HCL/H2O 50/50)
• Boiling Point: 385.2±32.0 °C (760 mmHg), Calc.^*
• Flash Point: 186.7±25.1 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Specific target organ toxicity - single exposure	STOT SE	3	H336
Eye irritation	Eye Irrit.	2A	H319
Acute toxicity	Acute Tox.	4	H302
Reproductive toxicity	Repr.	2	H361

Discovery and Applications

L-Tyrosine, a vital amino acid with the CAS number 60-18-4, plays an indispensable role in biological systems, serving as a precursor to neurotransmitters and hormones that regulate mood, metabolism, and stress response. With the chemical formula C9H11NO3, this compound is a non-essential amino acid, meaning the human body can synthesize it from phenylalanine under normal conditions. Its discovery and subsequent applications have significantly advanced fields ranging from biochemistry to medicine and biotechnology.

The story of L-Tyrosine’s discovery begins in 1846, when German chemist Justus von Liebig identified it in the protein casein extracted from cheese. The name “tyrosine” derives from the Greek word tyrós (cheese), reflecting its origin. Liebig’s work marked the first isolation of this amino acid, laying the foundation for understanding its role in protein synthesis. Early studies in the mid-19th century used rudimentary chemical techniques, such as hydrolysis and crystallization, to isolate tyrosine, with its structure later confirmed through advanced spectroscopic methods in the 20th century. The realization that L-Tyrosine is a chiral molecule, with the L-enantiomer being biologically active, further refined its scientific profile.

L-Tyrosine’s synthesis in the body occurs via the enzyme phenylalanine hydroxylase, which converts phenylalanine into L-Tyrosine by adding a hydroxyl group to the aromatic ring. This process, elucidated in the 20th century, highlighted its dependence on dietary phenylalanine and its critical role in catecholamine production. Industrially, L-Tyrosine can be produced through biotechnological methods, such as microbial fermentation using engineered bacteria, a development that has grown in prominence since the late 20th century.

The applications of L-Tyrosine are vast and impactful. In medicine, it serves as a precursor to neurotransmitters like dopamine, norepinephrine, and epinephrine, making it a target for treating disorders such as Parkinson’s disease, depression, and stress-related conditions. Supplementation with L-Tyrosine is studied for its potential to enhance cognitive function under stress, with clinical reviews supporting its safety. In biotechnology, L-Tyrosine is a building block for producing L-DOPA (used in Parkinson’s treatment), melanin, and other industrially significant compounds. Recent advances have also explored its use in enzymatic biosensors and as a substrate in microbial production systems, showcasing its versatility.

Despite its benefits, challenges include its limited solubility (0.48 mg/mL in water at 25°C) and the need for precise biotransformation conditions to avoid byproducts. Environmental concerns about large-scale production are prompting research into sustainable methods. Nonetheless, L-Tyrosine’s role as a biochemical cornerstone continues to evolve, from its cheese-derived origins to modern therapeutic and industrial applications.

Looking ahead, ongoing research aims to optimize its biotechnological production and explore novel derivatives for medical and material uses. L-Tyrosine’s journey from a cheese protein to a key player in human health and industry underscores the power of chemical discovery in shaping science.

References

Wojciechowska, A., et al., 2014. Structural, spectroscopic and magnetic properties of a novel copper(II) L-tyrosinato complex. RSC Advances, 4, 63147-63149.
DOI: 10.1039/C4RA10309B

Zheng, X.-F., et al., 2014. Synthesis of chitosan-gelatin molecularly imprinted membranes for extraction of L-tyrosine. RSC Advances, 4, 42478-42485.
DOI: 10.1039/C4RA05740F

Deng, P., et al., 2017. Novel phosphorescent Mn-doped ZnS quantum dots as a probe for the detection of L-tyrosine in human urine. Analytical Methods, 9, 282-286.
DOI: 10.1039/C6AY02107G