As noted earlier, it is possible to deliver peptides conjugated to 5-azidopentanoic acids. It is also possible to conjugate the azido group to the epsilon primary amino group using an inserted lysine. The azido group will always react with alkynes if CuSO4 or Cu are present, and this will lead to triazoles.
In most cases, the delivery of peptides is usually in the form of trifluoroacetate, also known as TFA salts. These salts can be used in a wide range of vivo experiments, as well as in most of the experiments involving cell cultures. However, there are certain cell structures, which display sensitivity to the TFA salts, thus making it impossible to use the TFA salts in some of the experiments. For such applications, it is recommended that the peptides should be delivered in acetate or chloride salts since these are considered to be natural counterions.
Fatty acid conjugated peptides
There are various applications where fatty acid conjugated peptides can be used, including eukaryotic cell toxicity and the study of antibacterial activities. In such applications, the N-terminus of the peptides are the exact locations where the fatty acid peptides are conjugated. Some of the peptides that can be conjugated to fatty acids include Lauric acid, Palmitic acid, Capric acid, Caprylic acid, and Stearic acid.
Fluorochrome conjugated peptides
It is possible to visualize fluorochrome peptides through fluorescence visualization or fluorescence microscopy techniques. It is possible to conjugate peptides directly to fluorphores at the N-terminus of the amino acids during the synthesis process. Conjugation is also possible at the C-terminus through an inserted lysine.
The process of peptide phosphorylation is possible with the use of threonine, serine, or tyrosine. It is possible to get synthetic peptides with one or two phosphorylation sites, though others can be made with more sites, and this is dependent on the sequence and the length of the desired peptide.