For Proteins, Form Shapes Function

Proteins are fundamental components of all living cells that participate in some of the most important biological processes, including cell growth and maintenance, movement and defense. They are complex molecules that consist of one or more chains of amino-acids, have distinct three-dimensional shapes and whose structure and structural dynamics directly influence their specific function.
Most proteins have a primary, secondary and tertiary structure, but some of them, like hemoglobin, also have a quaternary structure. The primary structure of a protein is represented by the ordered succession of its amino acids held together by covalent bonds. While in nature amino acids may possess either the D or L configuration, amino acids within proteins almost exclusively possess the latter, as this allows proteins to have binding sites with three-dimensional properties matching those of their ligands. From an evolutionary standpoint, the existence of D-amino acids in certain proteins and peptides is highly beneficial since many D-amino acid-containing peptides participate in defense roles. This group includes antibiotic activities of secreted peptides against neighboring bacteria as well as toxic effects of psycho-active peptides on larger predators. The mode of action for these peptides involves their insertion into another organism that often possesses defense mechanisms based on stereo-specific recognition, like in the case of proteolytic enzymes and antibodies. The presence of D-amino acids prevents the host’s defense system from recognizing and degrading the peptide (Kesssel,A. and Ben-Tal N. (2011) Introduction to Proteins: Structure, Function and Motion, London: CRC Press).
Certain portions of the amino acid chain tend to fold into...

... middle of paper ...

...orrect function, as it allows molecular recognition.

Works Cited

(Kesssel,A. and Ben-Tal N. (2011) Introduction to Proteins: Structure, Function and Motion, London: CRC Press)
( Travaglini-Allocatelli C; Ivarsson Y, Jemth P, Gianni S (2009) Folding and stability of globular proteins and implications for function, Current Opinion in Structural Biology 19 (1): 3–7).
.( Ali, M.H and Imperiali, B. (2005) Protein oligomerization: how and why. Bioorganic and Medicinal Chemistry 13: 5013-20.)
(Ponstingl, H., Kabir, T., Gorse, D., Thornton, J.M., (2005) Morphological aspects of oligomeric protein structure, Progress in Biophysics and Molecular Biology 89: 9-35).
(Hardison, R. (1999) The Evolution of Hemoglobin: Studies of a very ancient protein suggest that changes in gene regulation are an important part of the evolutionary story, American Scientist, 87 (2): 126).