mass spectrometry is used to identify amino acid sequence of a protein.
mass spectrometry is used to identify amino acid sequence of a protein.
how to identify amino acid sequence of a protein?
mass spectrometry
the primary structure of a protein refers to the sequence of amino acids in the polypeptide chain. the primary structure is held together by peptide bonds that are made during the process of protein biosynthesis. the two ends of the polypeptide chain are referred to as the carboxyl terminus (c-terminus) and the amino terminus (n-terminus) based on the nature of the free group on each extremity. counting of residues always starts at the n-terminal end (nh-group), which is the end where the amino group is not involved in a peptide bond. the primary structure of a protein is determined by the gene corresponding to the protein. a specific sequence of nucleotides in dna is transcribed into mrna, which is read by the ribosome in a process called translation. the sequence of amino acids in insulin was discovered by frederick sanger, establishing that proteins have defining amino acid sequences. the sequence of a protein is unique to that protein, and defines the structure and function of the protein. the sequence of a protein can be determined by methods such as edman degradation or tandem mass spectrometry. often, however, it is read directly from the sequence of the gene using the genetic code. it is strictly recommended to use the words "amino acid residues" when discussing proteins because when a peptide bond is formed, a water molecule is lost, and therefore proteins are made up of amino acid residues. post-translational modification such as phosphorylations and glycosylations are usually also considered a part of the primary structure, and cannot be read from the gene. for example, insulin is composed of 51 amino acids in 2 chains. one chain has 31 amino acids, and the other has 20 amino acids.
protein structure
the primary structure of a protein, its linear amino-acid sequence, determines its native conformation. the specific amino acid residues and their position in the polypeptide chain are the determining factors for which portions of the protein fold closely together and form its three-dimensional conformation. the amino acid composition is not as important as the sequence. the essential fact of folding, however, remains that the amino acid sequence of each protein contains the information that specifies both the native structure and the pathway to attain that state. this is not to say that nearly identical amino acid sequences always fold similarly. conformations differ based on environmental factors as well; similar proteins fold differently based on where they are found.
protein folding