Life on earth is interconnected. It is impossible to exist in isolation on earth, whether plant or animal. All organisms on earth relate to one way or the other, directly or indirectly to form a coexistence. Human beings belong to kingdom Animalia. The kingdom Animalia heavily depends on other kingdoms for survival. For instance, we depend on the kingdom Plantae for food and other crucial substances to our existence such as drugs and many other chemicals of life. The body systems of human beings work in a way that they can produce their chemical substances whenever the need arises. Sometimes the bodies alone cannot be sufficient in producing the important chemicals and therefore an additional source is needed. Other substances cannot be produced in our bodies at all, and yet we need a specific amount of them in our systems for us to function properly and keep a recommended basal metabolic rate. Such substances are obtained from external sources such as plants and microorganisms.
Substances that are needed by the body yet cannot be produced by the body itself and thereby have to be sourced from outside the body are called essential substances (M. A. 1976). Non-essential substances are those chemicals that are readily available in the body and are usually produced by the body itself. In life, plants, animal or microorganisms’ life, the most important substances are enzymes. Enzymes are chemical substances that are protein in nature that is used to control chemical reactions and processes in organisms. Life on earth would be impossible if there were no enzymes. Enzymes are however delicate substances. Concurrently, this is because enzymes are proteins in nature and as such, they possess the following characteristics:
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Damaged by heat
Enzymes are profoundly affected by extreme temperatures, just like all other proteins. There is an optimal temperature at which enzymes work best (M. A. 1976). The optimal temperature varies with the type of organism involved in the chemical reaction. In human beings, for example, the body temperatures are fixed at a certain range, at which the enzymes work well. When enzymes are subjected to too much heat or extreme temperatures, they are denatured. To be denatured means that their protein structures will be disoriented or simply destroyed. The afterward substance is, therefore, useless and cannot function in any way. Once destroyed by heat, proteins cannot be reversed. It is a permanent destruction.
On the other hand, when proteins are subjected to very low temperatures, they are deactivated. Low temperatures always slow down the enzymatic activities but extremely low temperatures will completely stop their activities, a state called deactivation. This state is, however, reversible (M. A. 1976). Deactivated enzymes can resume their normal activities once the optimal conditions are gradually re-provided.
Affected by the ph. of their medium
The potential of hydrogen in any provided medium will affect the activities of enzymes. Proteins are made up of certain chemicals and elements that are destroyed by the acidity or the alkalinity of substance.
Can be inhibited
Some substances inhibit the activities of enzymes in the body. These substances are called enzyme inhibitors. They prevent the enzymes from doing their usual work in controlling chemical reactions in the body. They inhibit through several ways. The most common way by which enzyme inhibitors inconvenience the proteins in their activities is through attaching themselves to the active sites of the substrates. They will thereby occupy all the sites and leave none for the enzymes. The inhibitors are most of the times inert or non-reactive. They just occupy the sites on the substrate and stay there until it’s too late or unless an alternative is provided.
Work with co-factors
Certain substances are similar to enzymes but are not enzymes. These substances help the enzymes work effectively and conveniently (M. A. 1976). The substances are proteins too. They work in close association with the enzymes.
There are different types of enzymes but they all have a similar function- slow down the chemical activities or speeds them up. Enzymes can be essential or non-essential. Enzyme tryptophan synthase is an example of the essential enzymes (Del, M. C. January 01, 2001). It is only found in Eubacteria, Protista, Fungi, archaebacteria and Plantae kingdoms. This essay talks about the sources and synthesis of the enzyme tryptophan synthase, its functions, and significance in medicine.
The evolution of enzyme tryptophan synthase
Proteins are the building structures or building blocks for the human and animal bodies. Proteins have many functions in not only the animal kingdom but also the Plantae kingdom. All micro and microorganisms need proteins for growth and development. Proteins are constituent components of many organs and substances in our bodies. They make up the important chemicals that we need in our bodies to avoid certain medical conditions or get rid of them completely. Most illnesses in animals, humans included is as a result of lack or insufficiency of certain proteins in the body (Catalá, 2015). Unless the protein substances are provided, the condition can be fatal, leading to complete failure of the body system. Some of the diseases that are associated with tryptophan are fructose malabsorption, lactose maldigestion, tuberculosis, poor growth and development of the body, depression, migraines and even anemia (Catalá, 2015). Tryptophan is used to make the drugs that are used on patients whose illness is associated with its deficiency.
Proteins are not easy to make. They are complex structures that have numerous specific functions and roles to play in our body systems. The proteins are also located in different organs in the body depending on their functions. Various substances facilitate the production of proteins in the body. Some of these factors form bases of protein formation while others initiate the whole processes of protein synthesis. One such important substance is the tryptophan.
Enzyme Tryptophan is believed to have emerged as a result of the combination of two basic genes, the TrpB1 and the TrpA. These genes came from the duplication of the trpB2 gene into trpB2i which entered the top operon. The other gene duplicate remained outside the operon as trpB2o where it acted as a salvage protein for indole. The TrpB2i gene evolved intoTrpB1 and formed permanent complexes with trpA. As such, it resulted in bidirectional activation thus formation of a bifunctional enzyme tryptophan synthase. Tryptophan is an important factor in medicine as it has many important uses. Tryptophan is the basis of life in all organisms.
Tryptophan is an amino acid that is used in the proteins biosynthesis. Proteins would not form in the absence of tryptophan (Del, M. C. January 01, 2001). Tryptophan contains an alpha amino group that exists in the protonated form, an alpha carboxylic acid group that exists in the deprotonated form and indole, a side chain which is classified as a non-polar, aromatic amino acid. All the three components of tryptophan are important in the biosynthesis of proteins. Among the important uses of tryptophan is the use as an anti-migraine drug and as a precursor to the two neurotransmitters (Catalá, 2015): serotonin and the melatonin. Tryptophan is used in the synthesis of niacin via kynurenine and quinilonic acids which act as the key biosynthetic intermediates. One of the most important plant hormone, auxin, is also synthesized from tryptophan.
Tryptophan is not naturally available. It must be manufactured by the plants and other organisms, except the animals. The enzyme tryptophan synthase plays a major role in the manufacturing of tryptophan.
The chemical action of enzyme tryptophan synthase
Enzyme tryptophan synthase primarily catalyzes the two final processes in the tryptophan biosynthesis. The enzyme is found typically as a α2β2 tetramer. The alpha subunit of the enzyme tryptophan synthase catalyzes indole-3-glycerol phosphate to form the indole and glyceraldehyde-3-phosphate, which is a reversible reaction.
The beta subunit speeds up the condensation of serine and indole forming tryptophan in a reaction that depends on pyridoxal phosphate (PLP). The alpha tryptophan synthase active sites are connected to the beta tryptophan subunit active sites by a hydrophobic channel that is contained within the enzyme. The hydrophobic channel is 25 angstroms long to facilitate the diffusion of the indole formed at the alpha subunits of the enzyme tryptophan synthase active sites to beta tryptophan active sites by the process of substrate channeling. Ii is worth noting that all the active sites of the enzyme tryptophan synthase are allosteric ally coupled.
The biosynthesis of tryptophan
As it was mentioned before, tryptophan is not found in animals and therefore it is synthesized by plants and microorganisms from shikimic acid when the phosphoribosylphrophosphate (PRPP) condenses with the anthranilate (Catalá, 2015). This process generates the pyrophosphate as a by-product.
During the process of tryptophan biosynthesis, the ribose moiety ring opens up and thereby is subject to the reductive decarboxylation which produces indole-3-glycerinephosphate. The indole-3-glycerinephosphate is in turn transformed to indole. In the last step of tryptophan biosynthesis, the enzyme tryptophan synthase catalyzes the indole and serine, an amino acid, to form tryptophan.
Tryptophan can also be produced industrially biosynthetically based on the fermentation of serine and indole (Del, M. C. January 01, 2001). In the fermentation process, a wild-type or sometimes a genetically modified bacteria like B.amyloliquefaciens, E. coli, B.subtilis or C. glutamicum .
The availability and the amount of the enzyme tryptophan synthase and the tryptophan protein are controlled and regulated by the repressor protein. In high amino acid, the repressor protein binds to the trp operon thus preventing transcription of the downstream DNA. When the levels of tryptophan are high, tryptophan biosynthesis is prevented through the negative feedback loop. When the protein level is low, transcription resumes in the trp operon. The trp operon is genetically organized to permit rapid and tightly regulated responses to cells’ internal and external changes in the tryptophan levels.
Life is important on earth. Many factors contribute to life. We should embrace all the factors that facilitate or enhance life. Our bodies as humans are equally important too. We should provide all the required conditions for our bodies to function well and achieve the normal basal metabolic rate. We should provide the essential chemical substances to our bodies in the required amounts for a better health. Enzymes are paramount in our cellular physiology. It is the cellular physiology of our bodies that lead to production of useful and integral units of life such as proteins. Enzymes that facilitate protein synthesis in our bodies thus growth and development like the enzyme tryptophan synthase should be given a profound priority in our diets.
References
Schomburg, D., Schomburg, I., & Chang, A. (2001). Springer handbook of enzymes . Berlin: Springer.
The enzymes: 2 . (1960). New York: Acad. Pr.
Tribe, M. A. (1976). Protein synthesis . Cambridge: Cambridge Univ. Press.
Liljas, A. (2004). Structural aspects of protein synthesis . Singapore: World Scientific Pub. Co.
Shaw, K., Turner, J., & Del, M. C. (January 01, 2001). Tryptophan and 5-hydroxytryptophan for depression. The Cochrane Database of Systematic Reviews, 3.)
In Catalá, A. (2015). Indoleamines: Sources, role in biological processes and health effects . New York: Acad. Pr.
