Peptiidi

Peptiidi is the Estonian term for a short chain of amino acids linked by peptide bonds. They range from dipeptides (two amino acids) to oligopeptides (a few dozen). When chains become longer and more complex, they are typically referred to as polypeptides and may fold into functional proteins. Peptiidi can occur naturally in organisms or be produced synthetically for research and medicine.

Chemistry and biosynthesis: A peptiidi bond forms by a condensation reaction between the carboxyl group of one amino acid and the amino group of the next, creating a covalent peptide bond. In biology, peptiidi chains are assembled directly by ribosomes according to genetic information. In the laboratory, chemists commonly synthesize peptiidi using solid‑phase peptide synthesis and related techniques, enabling precise control over sequence and modifications. Peptiidi may include nonstandard amino acids or chemical modifications at the N- or C-terminus to alter stability, activity, or pharmacokinetics.

Functions and roles: Peptiidi perform a wide range of biological tasks. Many peptiidi act as hormones (for example, insulin), signaling molecules, or neurotransmitters (such as enkephalins). Others serve as antimicrobial peptides in innate immunity or function as enzyme inhibitors, receptor agonists or antagonists, and structural components within larger proteins. Peptiidi can also be used as research tools and in therapeutic contexts, where their relatively small size and specificity are advantageous.

Applications and challenges: Peptiidi-based therapeutics show promise due to specificity and tunable activity, but face challenges including proteolytic degradation and limited oral bioavailability. Strategies to improve stability and delivery include cyclization, incorporation of D-amino acids, PEGylation, and formulation approaches. Analytical techniques such as mass spectrometry and Edman degradation are used to determine sequence and structure.