Amino acid side chains Flashcards
amino acid
an organic molecule with an amino group and a carboxyl group attached
at the centre, it contains an asymmetric carbon atom called an alpha carbon. as well as the amino group and the carboxyl group it also has a hydrogen atom attached to it, as well as an group/side chain.
why is diversity of side chains needed in amino acids
The chemistry of amino acid side chains is critical to protein structure because these side chains can bond with one another to hold a length of protein in a certain shape or conformation. Charged amino acid side chains can form ionic bonds, and polar amino acids are capable of forming hydrogen bonds.
why is protein structure important
the specific activities of proteins results from their intricate three dimensional architecture
a proteins shape determines how it works
what does a functional protein consist of
one or more polypeptides precisely twisted , folded and coiled into a unique shape
r chain in amino acids
may be as simple as a hydrogen atom, or it may be a carbon skeleton with various functional groups attached
the physical and chemical charachteristics of the side chain determine the unique charachtertics of a particular amino acid, thus affecting its functional role in a polypeptide.
side chain groups
nonpolar side chains - hydrophobic
polar - hydrophilic
acidic - usually negative in charge due to the presence of a carboxyl group, which is usually ionized at celllular ph
basic - have side chains with amino groups that are usually positive in charge
because they are electrically charged, acidic and basic side chains are also hydrophilic
tertiary structure
the overall shape of a polypeptide resulting from interactions between side chains.
polypeptide - consists of a helix and b pleated sheets
hydrophobic interactions
an interaction between side chains that contributes to tertiary structure
as a polypeptide folds into its functional shape, the amino acids with hydrophobic side chains usually cluster together at the core of the protein, out of contact with water.
once nonpolar side chains are close together, van der waals interactions help keep them together.
hydrogen bonds in tertiary structure
as well as van der Waals interactions between nonpolar molecules, hydrogen bonds between polar molecules
helps stabilize tertiary structure
ionic bonds
ionic bonds between negatively and positively charged side chains
disulfide bridges
two cystein monomers that have sulfahydral groups on their side chains are brought together by the folding of the protein.
