Enzymes as Drug Targets

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Enzymes as Drug Targets

Introduction

Enzymes are regarded as proteins that increase the rates of chemical reactions, or simply catalyze chemical reactions. In reactions involving enzymes, the molecules at the start of the process are known as substrates which are converted to different molecules known as products. Enzymes work like all catalysts by reducing the activation energy, resulting into increased rates of reactions such that products formation is accelerated and and reactions reach the states of equilibrium faster. Most chemical reactions within a biological cell require enzymes to as to occur at sufficient rates for life. Though, enzymes are discriminative in the selecting substrates and only accelerate a few reactions among many options. Enzyme activity in biochemical reactions may be influenced by other molecules referred to as inhibitors which decrease enzyme activity, and activators which increase the activity. Though, enzyme activity can also be influenced by other attributes such as temperature, chemical environment, and concentration of substrate amongst other factors.

Enzymatic Inhibitors

Most drugs and poisons are enzymatic inhibitors, and use of enzymes in disease diagnosis has derived tremendous benefits in biochemistry research and clinical chemistry. Drugs gives the molecules that bind onto enzymes and reducing enzyme activity can kill pathogens or correct metabolic imbalance. The discovery and improvement of drug molecules as enzyme inhibitors has become an important component of pharmacology and biochemical research. The factors that are used in judging medicinal enzymatic inhibitors are its specificity referred to as lack of binding to the other available proteins, and its potency ,which is also, known as its dissociation constant that indicates the concentration required to inhibit the enzyme.

When an inhibitor is bonded, a substrate is stopped from entering the active site or blocks the enzyme from catalysing the reaction; thus the inhibitor binding can either be reversible or irreversible. Irreversible inhibitors react with enzyme transforming it chemically through covalent bond formation. They do this by modifying the main amino acid residues required for the enzyme’s activity. Reversible inhibitors bind via non covalent bond formation, and various types of inhibition. This depends on whether the inhibitors can bind to the real substrate-enzyme complex, to the enzyme, or to both. Enzymes are therefore, very important for many biological processes. Inhibition of the main enzyme is an important means to create drugs that are targeted at certain pathogens or organs. Most drugs bind on the target receptor sites by blocking the physiological function of that protein or imitate its effect. Drugs that cause the protein receptor to respond in a similar manner are known as agonists such as morphine, nicotine, phenylehprine, and isoproterenol. Drugs that interact selectively with receptors and may result into no observed effect are known as antagonist, they just diminish the action of the agonist at the particular receptor site. Examples are beta blockers such as propranolols.

Enzyme Inhibited by Anti-Hypertensive

Antihypertensive refers to reducing or controlling high blood pressure, therefore, an antihypertensive drug blocks the creation of angiotensin II in the kidney, resulting into the relaxation of the arteries. This relaxation encourages the excretion of salt and water through the inhibition of the antigiotensin’s activity of enzyme conversion. This process can also be used in the treatment of congestive heart failure. Some of these drugs include Tenoretic, Chlorothiazide, Catapres, Cardura, Guanabenze, Apresoline, Minipress, Aldomet, Hytrin, Aldactone, amongst many more available in the market.

Angiotensin converting enzymes a target for anti hypertensive drugs, and the rennin antgiotensin systems is very important in the field of cardiovascular diseases. The use of angiotensine converting enzymes inhibitors has attracted a great deal of research in the investigation of possible benefits in different clinical conditions. Most clinicians have recommended these agents in the treatment of heart failure, hypertension, and myocardial infarction. Angiotensin converting enzyme inhibitors forms a group of anti hypentensin drugs that reduce high blood pressure. Conversion of inactive angiotensin I to potent agiotensin II happens faster in the passage all the way through the pulmonary circulation. Bradykinin is hastily inactivated within the circulating blood ultimately disappearing into a single passage throughout the pulmonary circulation. The same as the angiotensin I which vanish in the pulmonary circulation because it has been converted to angiotensin II. Angitensin II passes through the lungs without experiencing any loss. It has been thought for a long time that the inactivation of bradykinin and translation of angiotensin I to angiotensin II within the lungs was caused by a single enzyme.

Enzyme Inhibited by Anti-Inflammatory Drug

Most non steroid anti inflammatory drugs such as sulphasalazine, sulindac, indomethacin, ibufren, mefenamic acid, salicylic acid, and piroxicam. This group of drugs is generally referred to as NSAIDs, they are competitive inhibitors of avian liver phosphoribosylaminoimidalecarboxamide form transferase and bovine liver dihdrofolate reductase. However, aspirin and the antipyretic analgesic drugs acetaminophen and antipyrine are found to be weak inhibitors of these enzymes.

NSAIDs comprise an essential group of drugs constituting great therapeutic applications have been used in medication for a long period of time. They are mainly used in the management of rheumatoid arthritis and osteoarthritis. NSAIDs inhibit cyclo oxygenase enzymes in their management of chronic inflammatory conditions. Most of NSAID inhibits COX 1 and 2 enzymes, with the ones developed in recent times exhibiting greater inhibition of COX 2. Great efforts have been made towards the discovery of the ultimate drug that will treat inflammatory conditions and still continue to pose a challenge. They have adverse cardiovascular side effects. The challenges in developing of classical NSAIDs to selective COX 2 inhibitors pertaining to their mechanism of action, structural basis, and the recent discoveries

The peroxidise activities of the mitochondria in gastric mucosa is also inhibited by various NSAIDs. The inhibition can be withdrawn by adding the amount of concentration of iodide instead of water. It is found that indomethacin has no significant influence on submaxillary gland peroxidise activity. Therefore, NSAIDs inhibits gastric peroxidise efficiently if the acid pH is 5.2 instead of the natural pH. Other studies show that bathochronic movement of of the Soret band of the enzyme having indomethacin indicates its interaction near the heme part of the enzyme.

NSAIDs are an essential class of compounds or molecules that for rapid discovery of selective COX 2 inhibitors will be connected to the rational design approach.

Enzyme inhibited by anti-HIV drug

Anti HIV drugs have been found to inhibit retrovirus that is associated with prostate cancer and chronic fatigue syndrome. The xenotropic murine leukemia virus (XMRV) and other related viruses causes prostate cancer and chronic syndrome fatigue, which are diseases that are treatable and are already approved for HIV treatment.

Raltegarvir is the most potent drug against XMRV, and it is approved for only people with HIV infection, since it inhibits the integrase enzyme. This inhibition process prevents the virus from invading the DNA’s cells. Anti retroviral drugs are meant for the treatment of retroviruses infections, so the drugs have to be taken in a combination of four to three drugs in a therapy known as Highly Active Antiretropviral Therapy (HAART). Most clinicians offer antiretroviral therapy to those who have been diagnosed with AIDS, since the complexity involved in selecting the regimen. This comes about because of the severity of side effects, and the important role that patients must be treated with, and to prevent viral resistance.

Antiretroviral drugs always work in a combination, so clinicians can apply a mathematical model which measures the extend of the HIV infection into the immune system cells is inhibited by antiretroviral therapy. Most anti HIV drugs inhibit replication of human immunodeficiencuy virus, and such drugs could suppress HIV to make copies of it. The occurrences of HIV infections and deaths from AIDS continue due to increases in the amount of manifestations such as AIDS defining malignancies. The widespread occurrence is due to the viral resistance from earlier successful medicines, and to reverse the trend, other forms of therapy need to be developed. These could be anti cancer drugs that are applied in the treatment of HIV, and the development of antiretroviral medicines that could target the infected cells instead of the viral proteins.

Conclusion

Drug development process id s long and tedious, and sometimes may take more than ten years. The current available therapies for various illnesses where the drugs show inhibition of certain enzymes need more research and development. Although, many of the activation of the enzymes can be exploited therapeutically. It is a fact that the inhibition brought about by drugs could ne reversible or non reversible, so suppression of the gene factor is important. The suppression of genes may involve many steps such as protein synthesis, or the inhibition of nucleic acid biosynthesis, but are found to be very toxic, given that the drugs could not be selective in the sense of parasite or host.

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