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Cysteine (Cys) Unit Converter
Cysteine (Cys) is a semi-essential sulfur-containing amino acid, meaning the body can synthesize it from methionine. It is crucial for maintaining cellular integrity through the formation of the tripeptide antioxidant, Glutathione. Cysteine is also vital for the structure of proteins and antibodies via disulfide bonds.
In clinical chemistry, cysteine levels are monitored in conjunction with homocysteine and methionine. Deficiencies can impair antioxidant capacity, while abnormalities are noted in certain genetic metabolic disorders. Since cysteine contains a highly reactive sulfhydryl group, it readily oxidizes to its dimer, Cystine, outside of controlled laboratory conditions. This converter facilitates accurate switching between the standard molar unit ($\mu\text{mol/L}$) and mass-based units like $\text{mg/dL}$.
SI Units
RecommendedMicromoles per liter (Standard International).
Conventional Units
Clinical Context
Reference Range: Plasma cysteine levels typically range from 150 – 300 µmol/L. This measurement is often technically challenging due to rapid oxidation to cystine ($\text{Cys}_2$), which is also measured.
Measurements of cysteine, homocysteine, and methionine are collectively used to identify abnormalities in the **transsulfuration pathway**. Low cysteine levels can occur in certain nutritional deficiencies or conditions requiring high demand for antioxidant synthesis. The conversion factor is based on MW 133.10 g/mol: 1 mg/dL $\approx$ 75.13 µmol/L.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., µmol/L). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like mg/dL) are instantly updated.
Verify Units
Check the SI Units section. µmol/L is the standard unit for amino acid analysis.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
This calculator is for the Cysteine monomer. However, clinical assays often report the total of Cysteine and its dimer, Cystine.
Yes, amino acid levels fluctuate with diet. Overnight fasting is usually required for accurate baseline measurement.