The science of proteins
By: Jeffrey Stachnik
What are they?
Anyone who has ever stepped into a health facility, watched a fitness infomercial, and/or consulted a fitness enthusiast/ personal trainer before has probably heard the emphasis placed on, and importance of, consuming enough protein. “Get your protein, get your protein, and oh, one last thing- don’t forget to get your protein!” We hear it all the time in the fitness and health & wellness world, and the supplement industry has practically built an entire empire largely due to the marketing of protein-based powders alone, but what is the big deal? Well, it is no secret that protein is responsible for the repairing and growth of muscle tissue, but reserving its importance to that aspect alone is merely the tip of the iceberg. The fact of the matter is that without proteins, you and I, along with the existence of all life on this planet, would have never been able to exist in the first place!
Before we can get into fully understanding proteins though, it is vital in understanding the substrates that ultimately make up their composition. These substrates, known as, “amino acids”, are organic compounds comprising of a/an amine and carboxylic acid functional group, as well as an additional side chain whose structure is specific to that one amino acid’s function So, basically, what all that chemistry jargon means, is that we have a chemical containing the elements of carbon, hydrogen, nitrogen, and oxygen placed into a specific order, with a special branch that enables each amino acid to function differently from the next (chemical composition picture displayed on right [R-group representing specialized branch]). Amino acids are considered the building blocks for all biological molecules, and, in fact, proteins themselves are nothing more than a specific combination of amino acids, with different protein sources possessing different combinations. For example, the amino acid spectrum, or composition of a protein, in say, cottage cheese (primarily casein-based, secondarily whey-based protein source), differs greatly from the amino acid spectrum of that belonging to a whole egg (albumin/albumen-based protein source). In addition to this, the combination of amino acids will determine the molecular shape of the protein, and whether or not it is linear or folded. Observation of this aspect helps scientists determine the general function of the protein.
Simple enough, right? Well, as simple as that may seem, these amino acids and their combinations are responsible for the countless complex functions proteins enact that are necessary for both allowing and maintaining life within all living things. Without them, biological processes would be unable to properly function, and life, as we know it, would cease to exist. Currently to date, there are 20 amino acids recorded that are coded by the human DNA in order to produce proteins (with over 500 recorded existing in total). These 20 are divided into three categories- the essential, conditionally essential, and non-essential, and are as follows:
So, now that we have a general understanding of the chemicals that actually comprises of proteins, let us move on to the bigger picture, shall we?Amino acids belonging to the category of, ‘essential’ are considered so due to the fact that the human body cannot produce them on its own, and therefore it is necessary or essential, if you will, that we acquire them through diet and/or supplementation. ‘Non-essentials’, on the other hand, can be produced by the human body’s amazing natural ability to mix and match combinations from that of the essential amino acids, as well as other aspects of diet and metabolism, to create the non-essentials if/when needed. Lastly, we have the ‘conditionally essential’ amino acids. These amino acids come into play during times of illness, physical injury (whether it be an abrasion/cut or muscle fiber tear that resulted from working out), and/or stress (both mentally and physically), with the limitation(s) of their secretion by the human body varying in direct correlation to the degree of severity of the aforementioned factors. So, whether you cognitively realize it or not, your body is always hard at work when it comes to maintaining itself (even at a molecular level)! Ultimately, it is up to you though to make sure that your body is provided with enough of both the adequate levels and proper nutrients required to getting the job done!
What do they do?
Well, as mentioned previously in the article, the most common fact understood by the general public is that proteins are necessary for both muscle growth and repair. This growth and repair, however, is not strictly limited to muscle tissue alone. In fact, proteins are also responsible for the growth, proper development, and quality of one’s eyes, hair, nails, organs, and skin. Outside of reasons pertaining to growth and repair, proteins also play crucial roles for the providing of energy, production of antibodies and hormones, activity of enzymes, and transportation and storage of specific molecules within the body.
While not an optimal source of an individual’s diet to derive energy from, proteins can, nonetheless, be used as a source of viable energy. The main reason for proteins not being an optimal source of energy is simply because, unlike carbohydrates, proteins need to undergo multiple steps of conversion before they can be readily used as energy. First, the human body breaks down proteins into amino acids. From there, the body evaluates the current state of its own situation/well-being. If the amino acids are not needed for any of their typical functions (tissue repair, promotion of enzymatic-metabolic activity, and/or creation of other amino acids, neurotransmitters, and/or hormones) or there is no readily-available, stored energy (carbohydrate and/or fat), then the body will move onto the second and final step- the removal of nitrogen from the molecular structure of the amino acid(s) (which is actually a series of several steps). Amino acids actually possess a chemical structure very similar to that of glucose (sugar), with the important difference being the nitrogen chain. So, it is no mystery as to why the human body can recognize potential energy and make do of what is available in times of desperation. Energy, however, is far from being protein’s primary function and will only be when absolutely no other fuel source is available.
Another incredible function of the human body in relation to proteins is the concept of antibodies. Antibodies themselves are nothing more than highly specific proteins comprising of multiple polypeptides (large numbers of amino acids bound in a chemical chain) that function in two main ways. The first of these functions is to bind to and destroy a particular antigen, with an antigen being any chemical, foreign substance, and/or toxin that triggers an immune response within the human body. Antibodies are very specific in regards to which antigen they will bind to. In fact, an antibody will bind to one, and only one, type of antigen. This restriction is due to the lymphatic B-cell’s ability in encountering an antigen for the first time. When an antigen is initially identified, the B-cell will produce antibodies that are specialized in eradicating that particular antigen (the second function), thus, ultimately, making this the sole job of that very same B-cell who first encountered the antigen. From that moment on until the time in which the organism perishes, that B-cell will function only in producing antibodies specific for that antigen and nothing more.
Antibodies are not the only vital substances within the human body that consists of proteins. Practically all enzymes (identifiable on any bodily-chemical/substance/structure possessing the suffix “ase”), with the exception of ribozymes, are proteins in themselves. The general function of enzymes is to provide a catalyst, or trigger, to biochemical reactions, and without them, you andI would most certainly not be living. Think I am wrong?… Think again! The basal metabolic rate (B.M.R. [one of the most important concepts of life]) is determined by your enzymatic activity! Without metabolic activity your body would be unable to process nutrients, leaving absolutely zero kinetic energy to be available and halting thermogenesis from occurring. A zero kinetic energy results in the ability to no longer produce movement (both on a compound and molecular level), and no thermogenesis results in no heat production (dropping your body below the normal, safe level of 98.6 degrees Fahrenheit). So, are you trying to rev up that metabolism or keep it at a peak functioning rate? Yes? Well then, make sure you are getting your protein on a consistent basis!
In addition to contributing towards the kick-starting of biochemical reactions, proteins are also involved as the passageways and/or transporters of substances across cell membranes in the body that are either semi-permeable (selective in which substances are allowed to pass in and out) or non-permeable (no entry or exit) altogether. There are currently three known categories of protein-related passageways/transporters present within the human body. They are ATP-powered pumps, channel proteins, and transporters. ATP-powered pumps, or ATPases (an enzyme!), move substances along a channel against the typical flow of the gradient. Due to the fact that the substances are moving against an opposing force, energy is required to get the job done. This is where ATPase really shines! ATP, or adenosine triphosphate, is a major powerhouse of energy provision. So, what better scenario than this to have an enzyme whose main role is to drive energy?
This scenario can be compared to that of a salmon traveling upstream for the seasonal change, with the river/stream serving as the gradient, while the land represents the non-permeable cell membrane (since salmon cannot travel on land, the membrane will be considered entirely non-permeable, rather than semi-permeable). Salmon spend the remainder of the year gathering nutrients and bulking up so they have both the energy and strength for the long journey to their breeding grounds. When the time comes, they must put this stored energy to use by swimming against the current of the river/stream in order to reach the destination. If the salmon lacks the proper energy levels required, the journey will be all for nothing, as the salmon will fail to ever reach the breeding grounds. Without ATPase, the substances attempting to move through the gradient will meet the same fate as weak salmon, ultimately never reaching their destination.
The next of these categories is channel proteins. Their name is transitional to their function, as these types of proteins act as literal pathways for nutrients to travel through a cell membrane. These pathways, however, have the ability to act semi-permeably, and will open and close depending on the chemical response given off by a substance attempting to pass through them. In addition to this, different channel proteins require different methods of transportation. In fact, there are three different means in which substances can travel through a channel protein, one of which we already covered in the form of a cellular energy-driven movement, or active transport, made possible by ATPase. The remaining two methods are diffusion and osmosis, with the difference being that osmosis is specifically the movement of water. Neither requires cellular energy to be accomplished, however, osmosis does require kinetic energy stored in heat in order to transition from a higher to lower solution concentration.
Lastly, we have the general transporters, or carrier proteins. These proteins accomplish their job by binding to the substances and carrying, or transporting, them through either a channel protein or semi-permeable membrane. A transporter can only bind to one type of substance at a time, thus making this a much slower method than the previous two mentioned.
If you made it to this point, I would like to personally thank you for having taken the time to read this somewhat lengthy piece. I know I am personally guilty of sometimes opting out of a read due to length, so if at some point you began to drift off in thought and let your eyes keep scanning the pages, I totally understand! No need to worry though! Below, you will find the key points to this article summarized for your convenience. So, in case you missed something, here it is:
- All proteins are composed of amino acids, with different protein sources possessing different combinations.
- There are currently 20 known amino acids utilized by the human body and are divided into three categories: essential, conditionally essential, and non-essential.
- Proteins are utilized within the human body for tissue growth and repair, energy provision, antibody and hormone production, enzymatic activity, transportation and storage of specific molecules, and much, much more.
- Protein is not an optimal choice of one’s diet to derive energy from.
- Antibodies are proteins that bind to and destroy particular antigens.
- Each antibody becomes accustomed to dealing with only one type of antigen.
- Enzymes act as the catalyst, or trigger, to all biochemical reactions. Without them we cannot survive.
- There are 3 types of protein transporters: ATP-powered pumps (active transport), channel proteins, and general transporters/carrier proteins.
Well, there you have it- a basic understanding behind the science of proteins and how they work within the human body! This all merely scratches the surface though, as I could go on for days about how proteins function and their overall importance. Hmmm… a potential, continuing topic for later down the road, perhaps? I think so! So, stay tuned! Until next time, from all of us here at MA Fitness, we hope you have an absolutely amazing start to your July, and remember to always fight for your fitness!
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