The term peptides refers to small amino acid monomer chains that are linked by peptide bonds. There are covalent chemical bonds that can form a carboxyl group, caused when one amino acid reacts to another group of amino acids.
While these are similar to proteins, peptides are generally smaller than proteins, allowing them to be entered into a category of their own. As a general rule, a peptide is considered to be any amino acid chain that has 50 amino acids or less. This can be further divided into di-peptides, tetra-peptides, polypeptides and more, as necessary.
Peptides are growing in prominence in molecular biology because they can be used in animals to create peptide antibodies. People can use this knowledge to synthesize antigenic peptide sections for study instead of synthesizing full sized proteins. Peptides are also being used in mass spectrometry, to identify proteins based on their peptide mass or electrophoretic separations of proteins.
Cell Selective Antimicrobial Peptides
All types of organisms produce a wide variety of antimicrobial peptides that are gene encoded, but not positively charged, that are used to encourage innate immunity of microbial invasion.
There are a wide variety of lengths, compositions and secondary structures that these peptides take on; it doesn’t exclude the micromolar concentrations these peptides take on. This seems to be linked to the mechanism that they are used for.
Many of these peptides bind with bacterial phospholipid membranes, to create a threshold concentration.
Additional data suggests that cell selectivity relies on the molecular basis of peptides so they can bind to “negatively” charged bacterial membranes. The oligomeric state of the membrane solutions is also used to select the peptide. The “carpet” mechanism that regulates a peptide’s oligomeric state relies on a group of diasteromeric antimicrobial peptides. These may be used in design work to create synthetic versions of these chemicals for future research.
Link to the Origins of Life
Views of geometrical conditions that existed in primitive Earth indicate that peptides were created before other biomolecules existed.
It is suggested that peptides existed underneath primordial Earth in salt-induced conditions. This led to the formation reactions and absorption of clay materials that instigated the mechanism to stimulate life.
These properties favor biological peptides that could survive in a variety of environmental conditions.
Reaction inherent preferences of known peptides further the argument that these chemicals could evolve into the “right” proteins needed for animal development. This indicate that membrane proteins were developed from this chemical peptide reaction and self-replicating peptides. These ideas are being further developed as a way to explain how the first steps to create life on Earth transpired.
Identifying Prokaryotic and Eukaryotic Signal Peptides
A new method of identifying signal peptides from their cleavage sites has been developed, to further expand research into the existence of these chemicals.
This method is based on identifying neural networks that have been trained to accept different sets of prokaryotic and eukaryotic sequences.
Discriminating between uncleaved N-terminals and cleaved signal peptides is possible, though the precision for this method is not yet accurate.
This method has been found to perform more efficiently than previous prediction schemes that identified peptides, using genome data sets. These predications are available to the public using a www server, to further public research into peptide identification.
Peptides are frequently used to help researchers study protein structures as well as their functions in the body. Synthetic peptides are frequently used as probes in animals to see where peptide-protein interactions occur. Some research is also focusing on examining the effects of peptides on inhibiting of diseases, such as cancer, from developing in animal tissues.