aminopäästä

Aminopäästä is a Finnish term that literally translates to "amino end." In the context of biochemistry and molecular biology, it refers to the terminal end of a peptide or protein chain that has a free amino group. Proteins and peptides are polymers made up of amino acid subunits linked together by peptide bonds. Each amino acid has a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a side chain. When amino acids join to form a chain, the amino group of one amino acid reacts with the carboxyl group of another, forming a peptide bond and releasing a molecule of water. This process continues, creating a polypeptide chain.

The "amino end" is therefore the end of the chain where the first amino acid's amino group remains unreacted, and thus, is free. The opposite end of the chain, which possesses a free carboxyl group, is known as the carboxyl end or C-terminus. The directionality of a polypeptide chain is conventionally described from the amino end (N-terminus) to the carboxyl end (C-terminus). This distinction is crucial for understanding protein structure, function, and the processes of protein synthesis and degradation. For instance, during protein synthesis on ribosomes, the polypeptide chain is built from the N-terminus to the C-terminus. Many biological processes, such as enzyme activity and protein signaling, are dependent on the specific arrangement of amino acids and the presence of these terminal groups.