Peptide sequence or amino acid sequence is the order in which amino acid residues, connected by peptide bonds, lie in the chain. The sequence is generally reported from the N-terminal end containing free amino group to the C-terminal end containing free carboxyl group. Peptide sequence is often called protein sequence if it represents the primary structure of a protein. In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Diagram showing the π-bonded amino acids and the point of rotation A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... In chemistry, especially in organic chemistry and biochemistry, an amino group is an ammonia-like functional group. ... A carboxyl or carboxylic group is a functional group consisting of a carbon atom and an oxygen atom doubly bonded to each other. ... A protein primary structure is a chain of amino acids. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

Several deductions can be made from the sequence. Long stretches of hydrophobic residues may indicate transmembrane helices. Certain residues indicate a beta sheet area. If full-length protein sequence is available, it is possible to estimate the isoelectric point of the protein. Methods for determining the peptide sequence include deduction from DNA sequence, Edman degradation, and mass spectrometry. In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ... Within an integral membrane protein, a transmembrane helix is a segment that is alpha-helical in structure, roughly 20 amino acids in length and (though it may be presumed to lie within the protein, out of contact with the surrounding lipid bilayer) is said to span the membrane. ... Diagram of Β-Pleated sheet and bond structure of protein The β sheet (also β-pleated sheet) is a commonly occurring form of regular secondary structure in proteins, first proposed by Linus Pauling and Robert Corey in 1951. ... The isoelectric point (pI) is the pH at which a molecule carries no net electrical charge. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) or deoxyribose nucleic acid is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses). ... Edman degradation, developed by Pehr Edman, is a method of sequencing amino acids in a peptide. ... Mass spectrometry is a technique for separating ions by their mass-to-charge (m/z) ratios. ...