Proteins

1.0    INTRODUCTION

Proteins play an integral role in the body’s biological processes since they are responsible for regulating biochemical reactions as well as transporting molecules from one point of the body to another (Chou, 2011). In the case of plans, proteins contribute to the photosynthetic conversion of light into growth, thus forming basis of the structures such as tendon, hair, and skin. Various definitions of proteins have been developed over the years. For instance, they are considered to be substances comprising of amino acids, compounds, and elements such as nitrogen, carbon, oxygen, hydrogen and in some instances, Sulphur. In this case, examples of proteins include those found in beef. In biology, proteins are defined as molecules that are primarily composed of polymers of amino acids that have been joined together by peptide bonds (Monopoli et al., 2011). The major distinguishing factor between proteins and other substances such as fats and carbohydrates is former’s nitrogen composition.

2.0    PROTEIN COMPOSITION

Proteins are composed of amino acids linked together by peptide bonds, thus leading to the formation of a protein, otherwise known as, polypeptide. On their part, amino acids are composed of carboxylic acid (COOH), an amine group (NH2), and a carbon. Moreover, it contains the variable R group (Chou, 2011). Various types of protein structures exist, namely, primary, secondary, and tertiary.

The primary structure of proteins refers to the simplest type of the molecule. It is characterized by a simple linear chain of amino acids that are linked together to form a protein. On the other hand, the secondary structures exhibit more complexities and refer to a conformation of amino acids (Shannahan et al., 2013). The two major types of secondary structures of proteins include the α-helix and β-sheet. α-helices are considered to be right-handed and are identified by their resemblances to spiral staircases (Raterman et al., 2013). Moreover, they are stabilized by stabilized by hydrogen bonds. In the analysis of proteins, it is evident that some types of amino acids are more available in α-helices than others.

For instance, alanine which is a small amino acid is considered to more common in α-helices. On the other hand, the presence of Glycine is less common in this type of secondary structure (Monopoli et al., 2011). This can be attributed to the fact that the hydrogen bonds are internal with the R groups being external. Bulkier amino acids including proline are not present in the α-helix due to their ability to destabilize the structure (Wilhelm et al., 2014). There are two forms of β-sheets; parallel and anti-parallel with the former occurring when adjacent chains move in a similar direction. Anti-parallel is therefore evidenced by the opposite movements of such chains (Shannahan et al., 2013). Due to the distortion of hydrogen bonds, parallel β-sheets showcase less stability in comparison to the linear connections in the antiparallel β-sheets.

Tertiary structures refer to the collapsing of secondary structures, hence leading to the formation of 3D structures that can be seen in pictures. At this stage, the process of stabilization is extensively complex compared to the primary and secondary structures (Raterman et al., 2013). This is due to the infusion of ionic and hydrogen bonds as well as hydrophobic interactions and disulfide bonds that contribute to the stability of the structures. The four types of the tertiary structures include β-α-β motif; β-hairpin; α-α motif; and the Greek key motif.

3.0    BIOLOGICAL FUNCTIONS

Proteins serve vital purposes in various biological processes. Each type of protein serves a unique function (Van Der Lee et al., 2014). For instance, digestive enzymes such as amylase, pepsin, and lipase assist the process of digestion by catabolizing nutrients into monomeric units (Vogel & Marcotte, 2012). On the other hand, transport proteins including hemoglobin and albumin facilitate the movement of blood throughout the body (Basha, O’Neill & Vierling, 2012). Actin, tubulin, and keratin are some examples of structural proteins whose main functions include the construction of different structures whereas the hormones proteins (insulin and thyroxine) are tasked with the coordination of the activities of the body’s system (Wright & Dyson, 2015). On its part, defense proteins such as immunoglobulins protect the body from foreign elements with the contractile proteins affecting muscle contraction (Berlow, Dyson & Wright, 2015). Finally, the storage proteins (legume storage proteins and albumin) are critical during early development of the embryo since they provide nourishment.

4.0    DIETARY SOURCES

Protein contents vary from one food to another. The main forms of meals that are rich in proteins hence are considered to be sources of health benefits include seafood, milk, cheese, eggs, white-meat poultry, and beans among other foods (Zayas, 2012). However, there are only some amino acids that are essential to the human body whereas the rest are not. Examples of the essential ones include leucine, threonine, and valine (James, 2013). A complete protein refers to that which provides all the amino acids required by the body. These comprise meat, fish, quinoa, and soybeans. After the consumption of these foods, the digestion of proteins commences in the stomach with the help of gastric juices (Guenther et al., 2013). Thereafter, the proceeds through to the small intestines based on the action of enzymes from the intestinal lining. Finally, the bloodstream absorbs the amino acids and they are transported to the rest of the body.

4.1 Recommended Daily Intake

The intake of proteins is based on the age and gender of individuals as highlighted in the images below:

Table 1: Infants

Table 2: Children and Adolescents

Table 3: Adults

Table 4: Pregnancy

Table 5: Lactation

4.1 Factors Contributing to the States of Excess

Individuals are likely to experience protein excesses due to various reasons. Research has indicated that excesses of proteins in the body can be hereditary (Pennington et al., 2012). Under such cases, a person is likely to experience such symptoms if their lineage has been affected by protein excesses in the past (Marcello et al., 2012). Moreover, the possible causes of high blood protein include Hepatitis B and C, dehydration, and amyloidosis (Ward, 2012).

4.2 Factors Contributing to the States of Insufficiency

Low protein levels can be attributed to a liver disorder, kidney disorder, or an illness that does not allow for the protein to be digested appropriately (Hipp, Park & Hartl, 2014). Additionally, the symptoms of insufficiency are also evident in instances of severe malnutrition and ailments that lead to malabsorption (Markwald et al., 2013). Examples of such conditions include celiac disease or inflammatory bowel disease (IBD).  Additionally, the diets can also contribute to states of insufficiencies especially in cases where the individuals consume incomplete proteins. Athletes lacking essential and non-essential proteins in their diets may also experience states of insufficiency.

4.3 Signs and Symptoms of Insufficiency

Protein deficiency is caused by several factors including the loss of muscle mass due to the lack of insufficient dietary protein (Mithal et al., 2013). Additionally, edema, considered to be a classic symptom of kwashiorkor is also a sign of protein insufficiency. It is characterized by a swollen and puffy skin due to low amounts of human serum albumin.

5.0 CONCLUSION

Protein plays an integral role in the biological process in the body. As a result, it is essential to ensure that the types of foods that are consumed in such nutrients. Protein is primarily composed of carboxylic acid (COOH), an amine group (NH2), and a carbon. There are three types of protein structures including primary, secondary, and tertiary. The protein types determine the functions that they serve on the human body. Examples of these tasks include assisting in digestion, protecting the body from pathogens, and providing nourishment. The consumption volumes are influenced by age, gender, and conditions such as pregnancy and lactation. Due to the importance of proteins, insufficiencies may have adverse effects such as causing kwashiorkor.

 

 

 

 

 

References

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