Fundamentals of Peptide Science
Posted: Nov 15, 2017
The significance of peptides could not be emphasized too much, as they are an integral part of most biologic processes and could be found almost throughout every cell and tissue in the body. So here, I would like to explore some basics concerning peptides.
What is peptide?
As explained in the book "Principles of Biochemistry," all peptides are composed of amino acids chemically linked together. So, peptides can be properly defined as natural biological or artificially manufactured short chains of amino acid monomers linked by peptide (amide) bonds. There was a time when peptides are also called "small proteins", but with time passing they are eventually renamed and earned their exclusive name officially as peptides.
What is the difference between peptide and protein?
When it comes to the term peptide, the majority of general public must be puzzled by this question: what is the difference between peptide and protein? These two sounds very similar structurally as they are all made up of chains of amino acids that are held together by peptide bonds. This accounts for their great resemblance, but still, how to distinguish them?
First and foremost, peptides are smaller than proteins in size. Traditionally, peptides are defined as molecules that consist of between 2 and 50 amino acids, while in contrast, proteins refers to those molecules that are made up of 50 or more amino acids. Peptides can, more often than not, be subdivided into oligopeptides and polypeptides, whereas proteins are made up by one or more polypeptides joined together. Hence, it is safe for us to say that proteins essentially are very large peptides.
Except for the difference in size, another distinguishing factor might be structure. Unlike proteins whose complex structure are classified into secondary, tertiary, and quaternary structures, peptides are very much less defined as they are less complicated in structure and hence worth less attention.
Moreover, peptides may also differs from proteins in functions.
What are the categories of peptide?
Next, we are going to talk a little more about the classifications of peptide. But the fact is that there is not a perfect and unanimous classification system to classify peptides.
Firstly, when using function as a standard, peptides can be commonly classified into hormones, neuropeptides, and alkaloids. While by synthesis, peptides can be classified into ribosomal, nonribosomal, and peptonic. So naturally a peptide can fall into different categories if different standards are adopted.
Taking their research function into consideration, the popular classification of research peptides could possibly be cosmetic peptides, cell penetrating peptides, tumor antigen derived peptides, stable isotope labeled amino acids, etc. This is to facilitate the search work of researchers if they are to find the desirable peptides within the shortest time.
The status of peptides in the cosmetic industry has been increased a lot as some peptides can act as cellular messengers based on some scientific literature. So they are being tested and applied in skin care to combat wrinkles and other skin problems caused by aging or exposure to ultraviolet ray. This kind of peptides is called cosmetic peptides.
One interesting thing: there is also a journal called Peptides which collects original contributions in areas ranging from chemistry, biochemistry, and neurochemistry, endocrinology to gastroenterology, physiology, and pharmacology. This journal overally emphasizes all peptide researches and investigations related to all living beings including plants, insects, lower vertebrates, animals and of course humans.
The author is a true follower of biochemistry. BOC Sciences, the company he works for, is a trustworthy supplier of inhibitors.