Immunoglobulin

Justas Arasimavičius

Immunoglobulin Element of adaptive immune

mechanism Better known as antibody It recognize the foreign objects How they work (examples)

Animation1 Animation2

Structure of immunoglobulin

Two identical heavy (H) chains and two identical light (L) chains combine to form this Y-shaped antibody molecule

Disulfide bonds

Bonds between two amino acids result of the SH (sulfhydral) group of one amino acid covalently bonding to the SH group of another amino acid

Stronger than hydrogen bonds Eg. Hair proteins are held together by disulfide

bonds

Heavy chains

The heavy chains each have four domains Variable

domains (VH) Constant

domains (CH1,2,3)

Light chain

The light chains are constructed of two domains Variable (VL) Constant (CL)

Structure of immunoglobulin

The fragment antigen binding (Fab fragment)

The fragment crystallizable region (Fc region)

Antibodies bind to antigens by reversible, noncovalent interactions, including hydrogen bonds and charge interactions

How variety is maintained

The variable heavy chain is coded combining 3 genes (VH, DH, JH)

The variable light chain is coded combining 2 genes (VL, JL)

Most likely humans produce between 107 and 109 different shaped Fabs

Antibody Fab region Antibody (Fab)

molecular surface, with the PorA antigen superimposed.

The dark colored groove on the surface of the antibody matches precisely the shape of the PorA antigen

Any changes in the sequence of PorA in this region can disrupt antibody binding

http://www.bact.wisc.edu/themicrobialworld/neisseria.html

Antigen binding some pictures

Antigen binding some pictures

Structure of immunoglobulin

Functional consequences: (VH) and (VL) are

positioned to stereochemically react with antigen

The stem is good for mediate effector functions

Hinge

Two disulfide bonds in the hinge region unite the two heavy chains

The hinge allows the two antigen-binding Fab regions of each antibody molecule to move

Conclusion

Changes in the antigen binding site conformation are vital for antigen recognition

Herewith the variety of antibody conformation is vital for our health

Reference http://www.callutheran.edu/Academic_Programs/Departments/BioDev/omm/jmol/ig_div/star

t.html http://en.wikipedia.org/ http://www.path.cam.ac.uk/~mrc7/mikeimages.html http://www.tulane.edu/~biochem/med/igg.htm http://www.biology.arizona.edu/IMMUNOLOGY/tutorials/antibody/structure.html http://student.ccbcmd.edu/courses/bio141/lecguide/unit5/humoral/abystructure/

abystructure.html http://www.mun.ca/biochem/courses/3107/Topics/Antibodies.html Abul K. Abbas, Andrew H. Lichtman. Basic Immunology Functions and Disorders of the

Immune System. Second Edition 2004