تركيب البروتين | Protein structure
Protein
structure is the three-dimensional
arrangement of atoms in
an amino
acid-chain molecule. Proteins are polymers – specifically polypeptides – formed from
sequences of amino
acids,
the monomers of the polymer. A
single amino acid monomer may also be called a residue indicating a
repeating unit of a polymer. Proteins form by amino acids undergoing condensation
reactions,
in which the amino acids lose one water molecule per reaction in order to attach to
one another with a peptide bond. By convention, a chain
under 30 amino acids is often identified as a peptide, rather than a protein.[1] To be able to perform
their biological function, proteins fold into one or more specific spatial
conformations driven by a number of non-covalent interactions such
as hydrogen
bonding, ionic interactions, Van
der Waals forces,
and hydrophobic packing. To
understand the functions of proteins at a molecular level, it is often
necessary to determine their three-dimensional structure. This is the topic of
the scientific field of structural
biology,
which employs techniques such as X-ray
crystallography, NMR spectroscopy, and dual polarisation interferometry to determine the
structure of proteins.
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