Structure amino acid sequence

Fig. 2 Illustration of protein structure levels. Shown are primary structure (amino acid sequence), secondary structure (local order of protein chain, a-helix shown as an example), tertiary structure (assembly of secondary structure elements), and quaternary structure (relationship of different protein chain in multisubunit protein). (From Ref. 66.)...

Thus far we have concentrated on the primary structure (amino acid sequence) of a polypeptide. Higher level protein structure can be described at various levels, i.e. secondary, tertiary and quaternary ... 

Primary structure (amino acid sequence in a polypeptide chain)... 

Fig. 8. The four levels of structure in proteins, (a) Primary structure (amino acid sequence), (b) secondary structure (a-helix), (c) tertiary structure, (d) quaternary structure.

There are different classes of protein sequence databases. Primary and secondary databases are used to address different aspects of sequence analysis. Composite databases amalgamate a variety of different primary sources to facilitate sequence searching efficiently. The primary structure (amino acid sequence) of a protein is stored in primary databases as linear alphabets that represent the constituent residues. The secondary structure of a protein corresponding to region of local regularity (e.g., a-helices, /1-strands, and turns), which in sequence alignments are often apparent as conserved motifs, is stored in secondary databases as patterns. The tertiary structure of a protein derived from the packing of its secondary structural elements which may form folds and domains is stored in structure databases as sets of atomic coordinates. Some of the most important protein sequence databases are PIR (Protein Information Resource), SWISS-PROT (at EBI and ExPASy), MIPS (Munich Information Center for Protein Sequences), JIPID (Japanese International Protein Sequence Database), and TrEMBL (at EBI). ... 

Primary structure Amino acid sequencing, N-terminal Edman sequencing, peptide mapping... 

Since that time many more sequences have become available through the advent of recombinant DNA technology and the deduction of amino acid sequences from the base sequences of cloned DNA. At the present time, the primary structures (amino acid sequences) of 14 proteins of the transferrin family have been established. These include seven serum transferrins, from human 10, 36), pig (37), horse 38), rabbit 39), toad Xenopus laevis) 40), sphinx moth (M. sexta) 13), and cockroach Blaberus discoidalis 4) chicken 34, 35) and duck 41) ovotransfer-rins four lactoferrins, from human (11, 42), mouse 43), pig 44) and cattle 45, 46) and the human tumor cell melanotransferrin 47). All of these sequences are available from sequence databases such as EMBL and SWISSPROT. 

Ans. The primary structure (amino acid sequence) of a polypeptide chain determines the conformation. Interactions among R groups on a-carbons of different amino acid residues result in one conformation being favored over other conformations. 

Sequence analysis, the determination of the primary structure (amino acid sequence) of a peptide or protein. Prior to sequence analysis the determination of the amino acid composition amino acid analysis) and the number of different... 

The architecture of protein molecules is complex and can be described according to structural organization as primary structure (amino acid sequence), secondary structure (regular structures such as helical, pleated sheet, and coil stractures), tertiary structure (fold in three-dimensional space), quaternary structure (subunit structure) and quintemary structure (biomacromolecular complexes). Usually the overall three-dimensional (3D) architecture of a protein molecule is termed as its conformation, which refers to its secondary and tertiary structures. Between these two stractures, motifs (supersecondary structures) refer to the packing of adjacent secondary stractures into distinct structural elements and domains refer to identifiable 3D structural units that may correspond to functional units. The structures of most proteins with more than 200 amino acid residues appear to consist of two or more domains. 

Primary protein structure Amino acid sequence in a protein Secondary protein structure Shape of the backbone structure of a protein... 

Proteins are natural macromolecules consisting of 20 different amino acid residues arranged in a highly sophisticated three-dimensional structure. Protein structures can be described at four levels as shown in Fig. 23. 1 [5], including the primary structure (amino acid sequence), the secondary structure (conformation), the tertiary structure... 

DETERMINATION OF PRIMARY STRUCTURE AMINO ACID SEQUENCING... 

---