Lys in protein refers to lysine, an essential alpha-amino acid incorporated into polypeptide chains during protein synthesis. It's often abbreviated as Lys or K.
Lysine: An Essential Amino Acid
Lysine is classified as an essential amino acid, meaning that the human body cannot synthesize it, and it must be obtained through dietary sources. Its codons are AAA and AAG. It plays a crucial role in various physiological functions.
Key Characteristics of Lysine
Here's a breakdown of lysine's characteristics:
- Chemical Structure: It contains an α-amino group, an α-carboxylic acid group, and a side chain lysyl ((CH2)4NH2). The chemical formula is HO2CCH(NH2)(CH2)4NH2.
- Basic Amino Acid: Like arginine and histidine, lysine is considered a basic amino acid due to the presence of an amino group (-NH2) in its side chain, which can be protonated at physiological pH.
- Essential Nutrient: Humans must obtain lysine from their diet. Good sources of lysine include meat, fish, dairy products, eggs, and some plant-based foods like soybeans and lentils.
- Functions in Proteins:
- Structural Role: Lysine residues contribute to the overall structure of proteins through various interactions.
- Enzyme Active Sites: Lysine residues can be found in the active sites of enzymes, where they participate in catalytic reactions.
- Post-translational Modifications: Lysine is subject to various post-translational modifications, such as acetylation, methylation, and ubiquitination, which can alter protein function, localization, and interactions.
- Binding and Interactions: Its positively charged side chain facilitates interactions with negatively charged molecules, like DNA.
Significance of Lysine
Lysine is vital for numerous bodily functions, including:
- Protein Synthesis: As an essential amino acid, it's a building block for proteins.
- Calcium Absorption: Lysine aids in calcium absorption from the digestive tract.
- Collagen Formation: Crucial for the production of collagen, which is important for skin, bone, and connective tissue health.
- Immune Function: Plays a role in immune function by supporting the production of antibodies.
- Carnitine Synthesis: A precursor to carnitine, which is essential for fatty acid metabolism.
Lysine Deficiency
Lysine deficiency can lead to various health problems, including impaired growth, fatigue, nausea, and anemia. A balanced diet typically provides sufficient lysine.
