What molecule am I?
Selenocysteine is often called the 21st essential (protein-forming) amino acid. It is found in countless species of all domains of life. Much research has been reported on the in the North American plant Astragalus bisulcatus.
Scientists long believed that fungi were an exception to the broad prevalence of selenocysteine in life forms. But recently, Vadim N. Gladyshev, Marco Mariotti, and co-workers at Harvard Medical School (Boston) found selenocysteine-containing proteins in three fungus phyla. A few fungal genes that contain selenoproteins behave similarly to those in other organisms; but the mechanisms and purposes of other fungal 鈥渟elenogenes鈥� are as yet unknown.
Selenium鈥檚 wealth of natural and synthetic isotopes makes radiolabeled selenocysteine (Sec) a valuable tool in analytical chemistry and biochemistry. Specifically, 73Se-Sec is used in positron emission tomography (PET); 75Se-Sec in protein X-ray crystallography; and 77Se-Sec in high-resolution nuclear magnetic resonance (NMR) spectroscopy.
厂别濒别苍辞肠测蝉迟别颈苍别听hazard information
| GHS classification*: skin corrosion/irritation, category 2 | |
| H315鈥擟auses skin irritation |  |
| GHS classification: serious eye damage/eye irritation, category 2A | |
| H319鈥擟auses serious eye irritation | |
| GHS classification: specific target organ toxicity, single exposure; respiratory tract irritation, category 3 | |
| H335鈥擬ay cause respiratory irritation | |
*Globally Harmonized System of Classification and Labeling of Chemicals.聽
厂别濒别苍辞肠测蝉迟别颈苍别听fast facts
| CAS Reg. No. | 10236-58-5 |
| Empirical formula | C3H7NO2Se |
| Molar mass | 168.05 g/mol |
| Appearance | White to light yellow crystals or powder |
| Melting point | 143鈥�146 潞C |
| Water solubility | 鈮�400 g/L |
MOTW update
Loratadine was the Molecule of the Week for July 10, 2006. It is a venerable nonsedating antihistamine that is widely used to combat environmental allergens. Recently, Heather B. Miller, Meghan S. Blackledge, and colleagues at High Point University (NC) discovered that loratadine causes some otherwise antibiotic-resistant bacteria (e.g., Staphylococcus epidermidis and S. aureus) to 尾-lactam antibiotics and vancomycin (the September 5, 2016 惭翱罢奥).听
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