a)
Primary
b)
Secondary
c)
Tertiary
d)
Quaternary
Tertiary structure ,the
immunoglobulin fold is the domain involved which is a tertiary structure.Even
though Ig Has more than one polypeptide chain .For its functional fulfillment
domain is needed which is a tertiary structure.
Covalently-connected tertiary domains
In this class of protein, domains are usually formed as
modules covalently "strung together" on a single polypeptide chain.
The individual chains of antibodies are like this, strings of immuno-globulin
domains. However, light and heavy chains then combine to produce hetero-multimers,
which may even associate into higher complexes, as with IgM [http://swissmodel.expasy.org]
Higher Levels of Protein Organization
Primary structure of a protein refers to the covalent structure of a protein. It includes amino acid sequence and location of disulfide (cystine) bonds. Higher levels of
protein organization refer to noncovalently generated conformational properties of the primary structure. These higher levels of protein conformation and organization
are defined as the secondary, tertiary, and quaternary structures of a protein. Secondary structure refers to the local threedimensional
folding of the polypeptide
chain in the protein. The polypeptide chain in this context is the covalently interconnected atoms of the peptide bonds and a carbon
linkages that sequentially link the
amino acid residues of the protein. Side chains are not considered at the level of secondary structure. Tertiary structure refers to the threedimensional
structure of
the polypeptide. It includes the conformational relationships in space of the side chains and the geometric relationship between distant regions of the polypeptide chain.
Quaternary structure refers to the structure and interactions of the noncovalent association of discrete polypeptide subunits into a multisubunit protein. Not all
proteins have a quaternary structure.[Text book of Biochemistry with clinical correlation Thomas M Devlin ]
I had got another reference recently this from page 1351 Clinical laboratary medicine by
kenneth d macclatchey . This is what is refered
Thank you...
ReplyDeletehttp://www.biologyreference.com/Po-Re/Protein-Structure.html
ReplyDeleteHow Does Protein Structure Determine Function? For almost all biological functions to be expressed, two molecules must bind to each other. An antibody protein must bind to an antigen to provoke an immune response, a hormone protein (for example, a growth factor) must bind to a cell surface receptor to trigger a cell reaction, an enzyme protein must bind to a substrate to catalyze a reaction, and a protein containing the leucine zipper motif must bind to DNA to regulate gene expression. In order for two molecules to bind, they must recognize each other and form a series of noncovalent bonds. Recognition of two molecules for each other is termed "structural complementarity"; that is, the three-dimensional structures must complement each other in the shapes of the interacting surfaces (TERTIARY STRUCTURE). Analogies that have been used are a key fitting into a lock or the wooden square of a simple child's game that fits into the square-shaped cutout of a puzzle board.
• The overall structure of the Ig is determined by the primary ,secondary, tertiary and quaternary organization of protein.
ReplyDelete• Primary structure: sequence of amino acids that makes up the heavy and light chains
• Secondary structure: formed by the folding of the polypeptide chain upon itself into a series of antiparallel β pleated sheets.
• Tertiary structure: formed by the folding of β pleated sheets forming compact globular domains, which are connected to the neighboring domains by stretches of the polypeptide chain between regions of β pleated sheets.
Light chain has 2 such domains (VL and CL) and heavy chain has 4 such domains (VH, CH1, CH2, CH3 and CH4)
• Quaternary structure: Finally the globular domains (tertiary structure) of the adjacent heavy and light polypeptide chains interact in the quaternary structure forming FUNCTIONAL DOMAINS that enable the molecule to specifically bind antigen and at the same time perform a number of biological effector functions.
Immune complex is formed by the binding of antibody with soluble antigen.
This is from Kuby - Immunology.
Please share your thoughts on this.
Please see my newly added reference
DeleteThe structure of the immunoglobulin molecule is determined by its primary, secondary, tertiary, and quaternary protein structure. The primary aa sequence accounts for the variable and constant regions of the H and L chains. The secondary structure is formed as the chain folds back and forth upon itself forming an antiparallel B sheet which is stabilized by an intrachain disulfide bond and by hydrogen bonds that connect the peptide bonds in neighboring chains. The chains fold into a tertiary structure of compact globular domains. These domains of adjacent H and L chains interact in the quaternary structure to form domains that enable the molecule to specifically bind antigen.
Deleteheavy and light assication determine antigen binding specificity thats a quaternary structure
ReplyDelete