Proteins

Proteins

Proteins consists of one or more chains of amino acids
1. All amino acids have the same fundamental structure.
  1. A central carbon bonded to a hydrogen atom, a nitrogen-containing amino group a carboxylic group, and in "R" group that varies among different amino acids
2. Amino acids are commonly found in the protein organisms
3. They are polymers of amino acids joined.
They can have up to four levels of structure that determine its function
1. Interactions among amino acid R groups cause twists, folds and interconnections which gives proteins their 3D dimensional structure
  1. They are up to four organized levels of protein structure.
    1. Primary structure is the sequence of amino acids in a protein
    2. Secondary Structures are maintained by hydrogen bonds between the polar structures of amino acids
    3. Quaternary Structure refers to the structure of a protein macromolecule formed by interactions between multiple polypeptide chains. Each polypeptide chain is referred to as a subunit. Proteins with quaternary structure may consist of more than one of the same type of protein subunit. They may also be composed of different subunits.
    4. The tertiary structure is primarily due to interactions between the R groups of the amino acids that make up the protein.
      1. There are several types of bonds and forces that hold a protein in its tertiary structure.
        Hydrogen bonding in the polypeptide chain and between amino acid "R" groups helps to stabilize protein structure by holding the protein in the shape established by the hydrophobic interactions.
        Hydrophobic interactions greatly contribute to the folding and shaping of a protein. The "R" group of the amino acid is either hydrophobic or hydrophilic. The amino acids with hydrophilic "R" groups will seek contact with their aqueous environment, while amino acids with hydrophobic "R" groups will seek to avoid water and position themselves towards the center of the protein.
        Due to protein folding, ionic bonding can occur between the positively and negatively charged "R" groups that come in close contact with one another.
        Folding can also result in covalent bonding between the "R" groups of cysteine amino acids. This type of bonding forms what is called a disulfide bridge. Interactions called van der Waals forces also assist in the stabilization of protein structure. These interactions pertain to the attractive and repulsive forces that occur between molecules that become polarized. These forces contribute to the bonding that occurs between molecules.
The function of protein are related to their three-dimensional structures
1. When a protein is denatured, the importance of a higher level protein structure is obvius as its 3D structure is altered while leaving the primarly structure intact
2. The exact position and number of amino acids bearing specific R groups determine both the structure and the biological function of a protein
Amino Acids are joined by dehydration synthesis.
1. Amino Acids are added, one by one, until polypeptide chain is all completed

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	Criado por Rodrigo Sebastián De León Mendoza quase 5 anos atrás