Protein: Difference between revisions
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A protein is a biological | A protein is a biological polymer which is made up of [[Amino acid|amino acids]]. The [[Amino acids|amino acids]] are joined together with a peptide bond to form a [[Polypeptide|polypeptide]] chain. The [[Peptide bond|peptide bond]] is is formed by joining the ɑ-carboxyl group of an [[Amino acid|amino acid to]] the ɑ-amino group of another [[Amino acid|amino acid]]<ref name="null">Berg et al., (2006) Biochemistry, 6th edition, New York. Pg 34</ref>. A protein can be made up of a single polypeptide chain or multiple [[Polypeptides|polypeptides]] linked together. Examples of proteins include [[Enzyme|enzymes]], [[Receptor|receptors]] and [[Hormone|hormones.]] They are found in every form of life from [[Virus|viruses]] to [[Bacteria|bacteria]], [[Yeast|yeasts]] to humans.One important technique used to analyse proteins in [[SDS polyacrylamide-gel electrophoresis|SDS polyacrylamide-gel electrophoresis]] ([[SDS polyacrylamide-gel electrophoresis|SDS-PAGE]])<br> | ||
== Structure<br> | == Structure<br> == | ||
A protein has several 'layers' of structure <ref>Elliott.W.H, Elliott.D.C (1997) Biochemistry and Molecular Biology. New York, United States:Oxford University Press.pp.47-49.ISBN 0199271992</ref>. | A protein has several 'layers' of structure <ref>Elliott.W.H, Elliott.D.C (1997) Biochemistry and Molecular Biology. New York, United States:Oxford University Press.pp.47-49.ISBN 0199271992</ref>. | ||
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=== Primary Structure === | === Primary Structure === | ||
The [[Primary structure|primary structure]] is the sequence of [[Amino acids|amino acids]] joined togther by peptide bond. There are 20 different [[ | The [[Primary structure|primary structure]] is the sequence of [[Amino acids|amino acids]] joined togther by peptide bond. There are 20 different [[Amino acids|amino acids]] found in nature. This is determined by the [[DNA|DNA]] sequence that encodes for that particular protein, called the [[Gene|gene]]. <br> | ||
=== Secondary Structure<br> | === Secondary Structure<br> === | ||
[[Secondary structure|Secondary structure]] is the first level of protein folding. The two main folding structures of a protein are [[Alpha-helix|alpha-helix]] or [[Beta-sheet|beta-sheet]] depending on the sequence of [[Amino acids|amino acids]]. This, in turn, allows the protein to have a [[Hydrophobic|hydrophobic]] core and a [[Hydrophilic|hydrophilic]] surface. | [[Secondary structure|Secondary structure]] is the first level of protein folding. The two main folding structures of a protein are [[Alpha-helix|alpha-helix]] or [[Beta-sheet|beta-sheet]] depending on the sequence of [[Amino acids|amino acids]]. This, in turn, allows the protein to have a [[Hydrophobic|hydrophobic]] core and a [[Hydrophilic|hydrophilic]] surface. | ||
=== Tertiary Structure<br> | === Tertiary Structure<br> === | ||
[[Tertiary structure|Tertiary structure]] relates to the protein function. If the [[Tertiary structure|tertiary structure]] is wrong then the protein is unlikely to function properly. [[Tertiary structure|Tertiary structure]] is held together by either [[Hydrogen bonds|hydrogen bonds]] or [[Disulphide bridges|disulphide bridges]] depending on the [[Amino acids|amio acids]] present. Finally, if there is more than one peptide chains linked together to form a protein then you get a [[Quarternary structure|quarternary structure]].<br> | [[Tertiary structure|Tertiary structure]] relates to the protein function. If the [[Tertiary structure|tertiary structure]] is wrong then the protein is unlikely to function properly. [[Tertiary structure|Tertiary structure]] is held together by either [[Hydrogen bonds|hydrogen bonds]] or [[Disulphide bridges|disulphide bridges]] depending on the [[Amino acids|amio acids]] present. Finally, if there is more than one peptide chains linked together to form a protein then you get a [[Quarternary structure|quarternary structure]].<br> | ||
=== Quarternary Structure<br> | === Quarternary Structure<br> === | ||
One or more tertiary stucture of protein build up a [[ | One or more tertiary stucture of protein build up a [[Quarternary structure|quarternary structure]].<br> | ||
== See also<br> | == See also<br> == | ||
*[http://bms.ncl.ac.uk/wiki/index.php/Amino_acids Amino acid]<br> | *[http://bms.ncl.ac.uk/wiki/index.php/Amino_acids Amino acid]<br> | ||
== References<br> | == References<br> == | ||
<references /><br> | <references /><br> | ||
Revision as of 17:59, 14 November 2011
A protein is a biological polymer which is made up of amino acids. The amino acids are joined together with a peptide bond to form a polypeptide chain. The peptide bond is is formed by joining the ɑ-carboxyl group of an amino acid to the ɑ-amino group of another amino acid[1]. A protein can be made up of a single polypeptide chain or multiple polypeptides linked together. Examples of proteins include enzymes, receptors and hormones. They are found in every form of life from viruses to bacteria, yeasts to humans.One important technique used to analyse proteins in SDS polyacrylamide-gel electrophoresis (SDS-PAGE)
Structure
A protein has several 'layers' of structure [2].
Primary Structure
The primary structure is the sequence of amino acids joined togther by peptide bond. There are 20 different amino acids found in nature. This is determined by the DNA sequence that encodes for that particular protein, called the gene.
Secondary Structure
Secondary structure is the first level of protein folding. The two main folding structures of a protein are alpha-helix or beta-sheet depending on the sequence of amino acids. This, in turn, allows the protein to have a hydrophobic core and a hydrophilic surface.
Tertiary Structure
Tertiary structure relates to the protein function. If the tertiary structure is wrong then the protein is unlikely to function properly. Tertiary structure is held together by either hydrogen bonds or disulphide bridges depending on the amio acids present. Finally, if there is more than one peptide chains linked together to form a protein then you get a quarternary structure.
Quarternary Structure
One or more tertiary stucture of protein build up a quarternary structure.