Peptides are amino acid chains that are developed by creating amide bonds, more commonly referred to as peptide bonds given their prevalence in this structure. If these chains form enough bonds and create a large enough structure they can create proteins, which are found in all forms of life on Earth. Different types of proteins and peptides are found in different types of organisms, and in some cases the same peptide may be found in a variety of species but take on different reactions based on the physiology of the organism. While the term peptide is commonly reserved for smaller amino acid chains, they may be referred to as glutathione or small tripeptides when referring to chemicals specifically created naturally within the human body.
There has been an increase in the focus of peptide research in recent years. While initially research surrounding peptides focused on identifying peptides present in animals and their natural reactions.
As researchers worldwide are developing an increased understanding of which peptides are present in a variety of species and how these reactions can be triggered with a variety of applications, research is being altered to better understand how harvesting and applying these peptides to an animal without a stimulus within the body will affect bodily functions. This is performed both by harvesting peptides from an animal’s blood stream after they are triggered and creating a bonded chemical which mimics the structure of a natural peptide.
Storing Peptides during Research
Long term storage of peptides during research should be undertaken with great care to ensure the stability of the product, maximizing the potential for uniform results throughout the testing period.
- In general, long term storage of peptides is somewhat problematic as peptides are designed to break down for use in a variety of bodily functions when they are exposed to the elements, or exposed to bodily tissues after application. Many peptides have been altered to increase stability both during storage and after application; though these altered peptides may show alternative reactions to their natural counterparts.
- In general, lyophilized peptides have higher stability than other types of chemicals, which makes these ideal for research that will be ongoing for years at a time. Lyophilizates can be stored for years if kept at -10 degrees Celsius or lower with no signs of degradation. However, once these peptides have been reconstituted into a solution their stability is significantly more limited.
- Peptides are susceptible to degradation when exposed to any items of bacterial or protease origin, so a filtration system used after reconstitution increases the risk of damage to these solutions. Any peptide solutions used should be carefully stored in containers that have been sanitized to further reduce the risk of degradation before they can be applied to animal test subjects. Sterilized water is an ideal material for reconstitution for this reason.
- Peptides that contain residues of tryptophan or methionine are at risk for oxidation which can cause impurities even if the solution is not exposed to microbial agents. In order to reduce or eliminate this risk, peptides that contain these amino acids should be reconstituted using oxygen free solvents.
When determining the pH of the peptide solution for application in animal test subjects, most peptides will maintain more stability when kept in an acidic environment. It is generally recommended to mix peptide solutions at a pH of 3-6 but solutions of peptides that are frozen in aliquots should be subjected to as few freeze-thaw cycles as possible. Reconstituted peptides should also be relyophilized to help ensure the highest level of stability possible.
Peptide Reactions in Female Test Subjects
Many peptides have been used in research for building muscle and increasing the size of an animal which naturally lends itself to male physiology, but new research is attempting to understand how these peptides affect female physiology as well.
- Many peptides are designed to create a pulse of growth hormone in the body which can then be controlled to create reactions within the animal. Male animals have three main growth hormone pulses from their pituitary gland, the largest of which occurs at night. With a basic understanding of this, researchers are able to stimulate or manipulate these pulses to create reactions as desired.
- Female animals appear to have a continuous amount of growth hormone in their system with slightly elevated levels in the plasma. Therefore, many of the methods used in traditional research, stimulating the pituitary gland to create bursts of growth hormone are largely ineffective when applied to female animal test subjects.
- Only certain peptides have been found to be particularly effective in creating reactions in female test subjects if the ultimate end goal is to create substantiated growth. The first is conjugated CJC 1295, an hGH secretogue that contains an additional lysine molecule that will help with facilitating a DAC complex so that the peptide has an 8 day half-life.
- A single application of CJC 1295 has been found to mimic the normal growth hormone pulsate cycle of a female animal by signaling growth hormone releasing hormone to increase the amount of peptide that individual cells secrete.
- The second peptide that appears to be effective in working along with the natural female growth hormone cycle is GHRP-based peptides, particularly ghrelin or GHRP-6. These peptides can act on different somatotrope cells which are responsible for releasing growth hormone by increasing the number of these cells that are releasing growth hormone at any given time. This will not increase the amount of growth hormone that is produced by the cells like CJC 1295, so these peptides may be applied to animal test subjects simultaneously if need be.
There are a variety of other peptides that are regularly applied to female animals in addition to these two peptides. Much of this research focuses on the differences in reactions that are seen when these peptides interact with an alternative growth hormone cycle. Some peptides are also designed for use in vivo or in vitro which helps to eliminate the difference in reaction that could eliminate the effectiveness of peptides in other circumstances.
Creating Research Solutions
When reconstituting a peptide, care should be taken to ensure that the proper environment is created to stabilize the product.
- In general, peptides can be mixed with bacteriostatic water without risk, though peptide manufacturers will typically specify any additional liquids that are recommended for this purpose. There is one exception to this rule, as IGF peptides should only be reconstituted with acetic acid.
- Peptide solutions can be made stronger or weaker as necessary based on the amount of liquid that is added to the syringe prior to the application. As long as the total amount of the solution is not changed throughout the application process there should be no alteration in the behavior or stability of the chemical.
Peptide solutions are typically measured using micrograms, which should remain constant throughout the application process. Any peptide solutions should be kept refrigerated until the moment they will be applied as these solutions begin to lose stability rapidly after they are reconstituted.
Most solutions cannot last longer than 2 weeks in this state, but the vial should contain any instructions regarding how long they should last and what sings you should check for before applying the solution to an animal test subject to ensure that the peptide will behave as necessary for the nature of your experiment.