Biochemistry-proteins

Proteins are linear polymers built from 20 different L-α-amino acids All amino acids are the general structural features including the carbon α to the amino group a carboxyl group and a variable side chain Only praline differs from this basic structure because it contains an unusual ring to the amino group of the N-end forcing half of the amide CO-NH in a side chain of amino acids conformation The fixed rules detailed in a list of standard amino acids has different chemical properties that produce three-dimensional structure of proteins and is therefore important for protein function Amino acids in the polypeptide chain linked by a peptide bond formed in a dehydration reaction Once connected in the chain of proteins called single amino acid residues and a circuit connected to carbon nitrogen and oxygen atoms known as a backbone main chain or protein peptide bond has two resonance forms that contribute some double bond character and inhibit rotation around its axis so that the carbon alpha approximately coplanar The other two dihedral angles in the peptide bond determine the form taken by the local backbone of proteins
Since the chemical structure of individual amino acids the protein chain has directionality End of the protein with a carboxyl group known as the free ends of carboxyl or C while the end with a free amino group known as the ends of N or amino acids
Proteins are generally used to refer to the complete biological molecule in a stable conformation while the peptide is generally reserved for short amino acid bloomers often lacking a stable three-dimensional However the boundary between the two is not well defined and is usually near 20-30 residues Polypeptide can refer to any linear chain of amino acids usually not long but often implies the absence of defined conformation