PAPER : ENZYMES

CHAPTER I

INTRODUCTION

1.1     Background

Enzymes are biological catalysts responsible for supporting all the chemical reactions within the cells maintain homeostasis. Catalyst  can be any enzyme or enzymes are not compounds of metals. Because of its role in maintaining life processes, inspection and regulation of drugs that affect the action of the enzyme is the key factor in the clinical diagnosis and therapy. Macromolecular components of all enzymes are proteins, except for the class of RNA catalysts, called ribozymes.

Ribonucleic acid molecules are ribozymes that catalyze reactions at phosphodiester bonds in RNA.  Different enzymes catalyzing the metal catalyst. In essence, a living cell  biochemical activity called metabolism, and this process is strongly influenced by the continuance of an enzyme. Cell activity as replacement of damaged cells, the conversion of food into energy sources, expenditure remains of metabolism, reproductive processes and all activities of the body such as mobilization, all require the enzyme to normal processes.

Most enzymatic reactions are reversible  enzyme protein that serves to accelerate the reaction by lowering the activation energy and does not alter the reaction equilibrium. The enzyme is highly specific, it is also found in all tissues and body  fluids. Nearly all life processes depend on the enzyme activity.

1.2 Objectives of Writing
a. Describe the classification of enzymes
b. Explain the mechanism of action of the enzyme itself
c. Knowing the arrangement as well as inhibitors of enzyme activity
d. Knowing the factors that affect the catalytic activity of enzymes

1.3  Formulation of Problem
a. What factors are affecting the catalytic activity of enzymes?
b. Why the enzyme is needed by the body?
c. How does the mechanism of action of the enzyme?
d. How the enzyme nomenclature classification rules?

1.4 Benefits of Writing
The benefits of writing this paper is:
a. Can provide information on enzymes in general and specifically.
b. As a learning reference for the readers.

CHAPTER II

DISCUSSION

2.1 History of discovery of Enzymes

In 1800, it has been known that gastric secretion can digest meat and saliva could convert starch into sugar. Then, in the next few years, Louis Pasteur concluded that fermentation of sugar into alcohol by yeast that produces "fermen". Furthermore fermen was named as the enzymes in the yeast when it is considered inseparable from living cells.

In 1897, Eduard Buchner succeeded in extracting the active form of the yeast cell, a series of enzymes that catalyze the fermentation of sugar into alcohol. This proves that the enzyme outside the living cell is able to catalyze the substrate. Then in 1926, James Sumner was first isolated in crystalline form of the enzyme, the enzyme urease, sinceurease crystals a protein molecule, then Sumner concluded that all enzymes are proteins. 

Subsequently in 1930, John Northrop and colleagues crystallized Pepsin and trypsin which are both also a protein molecule. The concept of "enzymes are proteins" continues to survive today, although it is known that some enzymes require combination with a prosthetic group (non protein) for catalytic activity, and now also have found a molecule that has catalytic ability as enzymes, but not a protein molecule, namely RNA molecules.

2.2 Definition of Enzymes

The enzyme is a protein that serves as biocatalysator. Most enzymes are proteins where there is little ribonukleoprotein found and some of these groups is dominant catalytic activity of RNA rather than protein. The enzyme catalyzes a chemical reaction that takes place in the cell body. Catalyst is defined as the acceleration of chemical reactions by some of the compounds where the compounds are not chemically changed permanently.

Bound enzyme catalyzed while the reactants, and returned to normal after the product is formed. For example: catalase which catalyze the decomposition of hydrogen peroxide into water and oxygen, the reaction is as follows:

2H₂O₂ → 2H₂O + O₂

One molecule of catalase can break 40 million molecules of hydrogen peroxide per second.

2.3 Enzyme Characteristic

The properties of the enzyme can be described as follows:

a.      A protein

The enzyme is a protein that is a compound composed of amino acid sequence that is bound to one another by peptide bonds, please note that the properties owned by a protein, of course, also owned by the enzyme.

b.      Is biokatalisator

Enzyme known as a catalyst for working as a catalyst in the lives of living things. The catalyst in question here is the ability of enzymes to help speed up chemical reactions without being reacted or affected by these chemicals.

c.       Specific enzymes work

The enzyme is highly specific, both types of reactions and substrates in the sense that each enzyme only works for one compound (substrate) only.

d.      Have the ability to set

The enzyme reacts with the substrate did not participate or products. Activity can be controlled according to the needs of the organism itself. Several enzymes are synthesized in an inactive form, and will be activated by appropriate conditions and time (allosteric enzyme), an inactive precursor called zymogen.

e.       Using bond nonkovalen

The power of connecting with the enzyme substrate generally use bonding nonkovalen like hydrogen bonding, ionic interactions, and hydrophobic interactions. Enzyme substrate interactions are weak interactions, especially when the atom looks more than 1A from the other. So that the binding of the enzyme with substrate requires both molecules to the surface adjacent to the contact width. This configuration requires that complement each other between the substrate with the enzyme, and this explains the specificity of most enzymes.

f.        Speed ​​up chemical reactions by lowering the activation energy is the  initial energy required to initiate a chemical reaction

Enzymes speed up reactions inside the cell by allowing the reaction to occur effectively at a lower temperature than the body (37 ° C). Enzymes work the activation energy required for reactions that occur.

g.      It work very fast

In a chemical reaction, enzymes are generally required very little, but their influence on the reaction rate is very large (fast), and can be used repeatedly.

h.      Can work in a reversible

In a chemical reaction, enzymes generally work in one direction, although some are able to work in two directions. For example, the reaction is a lipase that helps direct the formation of fat.

i.      May be assisted by the cofactor

The enzyme is able to work with the help of nonprotein material called cofactors.

2.4 Types of Enzymes and the Role

1.         Ptyalin Enzymes

Ptyalin enzyme found in saliva, produced by the salivary glands.Ptialin enzyme functions to convert starch (starch) into glucose.

2.         Amylase Enzymes

Amylase enzyme produced by the salivary gland (parotid) glands in the mouth and pancreas. The action of the enzyme amylase: starch is often known as starch or starch. Starch is a carbohydrate or saccharide which has a molecular complex. The enzyme amylase breaks starch molecules is a saccharide with a simpler molecule that is maltose.

3.         Maltase Enzymes

Maltase enzymes contained in the duodenum, serves to break the molecule of maltose into glucose molecules. Glucose is a simple saccharides (monosaccharide). Glucose molecules are small and lighter than on maltose, so that blood can be taken to transport glucose to the cells that need.

4.         The enzyme pepsin

The enzyme pepsin is produced by glands in the stomach of pepsinogen. Furthermore pepsinogen reacts with stomach acid into pepsin. The workings of the enzyme pepsin: enzyme pepsin break down complex protein molecules into simpler molecules that peptone. Peptone molecules need to be broken down again in order to be transported by the blood.

5.         The enzyme trypsin

Trypsin enzyme produced by the pancreas gland and channeled into the duodenum (duodenum). The workings of the enzyme trypsin: amino acid has a much simpler molecule when compared to peptone molecules. This amino acid molecules are transported blood and carried to every cell in need. The next cell will re-assemble amino acids amino acids to form proteins to the various needs of the cell.

6.         The enzyme rennin

The enzyme renin is produced by glands in the stomach wall.Function of the enzyme renin to precipitate the casein from milk.Casein is a milk protein, often called cheese. After the casein is precipitated from the milk of substances in breast milk can be digested.

7.         Hydrochloric acid (HCl)

Hydrochloric acid (HCl) commonly known as stomach acid, produced by glands in the stomach wall. Hydrochloric acid used to kill certain microorganisms that enter the food together. Production of hydrochloric acid which is unstable and tends to excess, can cause inflammation of the stomach is often called the disease "mag".

8.         Bile
Bile is produced by the liver and stored in the gallbladder. Contain bile pigments bilirubin and biliverdin which causes the rest of the digestive yellowish dirt. Rombakan bile from red blood cells (erithrosit) are old or have been damaged and is used to form new red blood cells. Function of bile is to break the fat molecules into granules finer so as to form an emulsion. The fat emulsion was tangible this will further digested into molecules that simple anymore.

9.         Lipase enzyme

Lipase enzyme produced by the pancreas gland and then passed into the duodenum (duodenum). Lipase enzyme is also produced by the stomach, but the amount is very small. The workings of the lipase enzyme: Lipid (such as fats and oils) are compounds with large molecular complexes. Lipid molecules can not be transported by the lymph fluid, so it needs to be broken down first into smaller molecules. Lipase enzymes break down lipid molecules into fatty acids and glycerol molecules which have a simpler and smaller.Fatty acids and glycerol are not soluble in water, the transport carried by the lymphatic fluid (lymph).

2.5  Classification of Enzymes

A.    Naming Enzymes

Traditionally, enzymes are named simply by people who find it. Naming system continues to change with the development of science, and the system of naming enzymes as well as the more complex and comprehensive classification.

Subsequent development of an enzyme's name usually comes from:

Ø  Substrate or the chemical reaction catalyzed by the addition of end-ase.

For example, lactase, alcohol dehydrogenase and DNA polymerase.

Ø  Based on the type of chemical bonding substrate is digested by enzymes, plus the suffix-ase.

For example, if the digest is sulfate, then the given name of the sulfatase, whereas when it is called a substrate peptide peptidase.

Ø  Based on the type of reaction, for example, transferase, oxidase, dehydrogenase, and others.

B. Classification of Enzymes

No.	Classification	Type of reaction	Biochemical properties. .	Reaction picture	examples of Enzymes
1.	Oksido reductase	Reaction of oxidation and reduction	Catalyses the reduction / oxidation, H or O atom transfer or electron from one substrate to another.	AH+B → A+ BH (reduced) AB+C → AO (oxidized)	Dehydrogenase, oxidase
2.	Transferase	Removal of functional groups	Works by moving the functional groups between donor and acceptor molecules. Kinasesare specialized transferases that regulate metabolism by transferring phosphate groups from ATP to other molecules.	AB+C → A+ BC	transaminases. kinase
3.	Hydrolase	Hydrolysis reaction	Works by adding water to remove the ties and hydrolyse.	AB+H2O → AOH+BH	Lipase, amylase,peptidase
4.	Lyase	The addition of the double bond or vice versa	Works by adding water, ammonia, or carbon dioxide, forming a double bond or the release of these elements to produce a double bond.	RCOCOOH → RCOH+ CO2
5.	Isomerase	Isomerization reaction	Worked for several types of isomerization reactions: L to D isomer, the reaction mutateon (replacement of functional groups) and others.	AB → BA	isomerase, mutase
6.	Ligase	Formation of new bonds CO, CS, CN or CC with ATP.	Working to catalyze the merger of two chemical groups (or binding)by using energy from ATP.	X+Y+ATP → XY + ADP = Pi	synthetase

2.6  Mechanism of Enzyme

A.    Competitive Inhibitor

Inhibit the enzyme by occupying the active enzyme. These inhibitors compete with substrate to bind to the active enzyme. Inhibition is reversible (can return to again) and can be eliminated by increasing the substrate concentration.

Competitive inhibitors such as malonate and oksalosuksinat, which competes with thesubstrate to bind to the enzyme succinate dehydrogenase, an enzyme which works on oseli substrate succinate.

B.     Noncompetitive Inhibitor

These inhibitors are usually in the form of a chemical compound that is similar to thesubstrate and bonded to the side in addition to the active enzyme. This bond causes theenzyme changes shape so that the active enzyme to the substrate is no longer appropriate. For example penicillin antibiotics inhibiting bacterial cell wall constituentenzymes. This inhibitor is reversible but can not be eliminated by adding the substrate concentration.

Picture: Work enzyme like a lock-key child B. Competitive and

noncompetitive inhibitor

C.    Irreversible Inhibitors

These inhibitors bind to the active enzyme is strong that can not be separated. The enzyme becomes inactive and can not return to normal (irreversible). For example, diisopropilfluorofosfat which inhibit the action of acetylcholine-esterase. Molecules are always moving and colliding with each other. If a molecule is an enzyme substrate molecules striking the right it will be attached to the enzyme. Points of attachment of the substrate on the enzyme molecule called active side.

There are two theories that explain the workings of enzymes, namely:

1.        Key theories and padlock

This theory was proposed by Emil Fischer in 1894. According to this theory, the enzyme is very specific work. Enzyme and substrate have the same geometric shapes complement each other just so they can attach. Here is a picture display of the workings of a key enzyme in theory and padlock:

Emil Fischer proposed that both enzymes and substrates have to meet each other geometric shapes. This is often referred to as a model of "Lock and Padlock". When this model explains enzyme specificity, it fails to explain the transition state stabilization is achieved by enzymes. This model has proven inaccurate and induction accuracy of the model is now the most widely accepted.

2.        Accuracy of the induction theory

In 1958, Daniel Koshland proposed modifications to the model and a padlock key, because the enzyme has a flexible structure, the active site is continuously changing its shape according to the interaction between enzyme and substrate. As a result, the substrate does not bind to the active site is rigid. Orientation of the side chains of amino acid changes with the substrate and allow the enzyme to perform catalytic functions. In some cases, such as glycosidase, the substrate molecule also changes slightly as it enters the active site. Active footprint will continue to change its shape to be fully bound substrate in which the final form and content of the enzyme determined.

The main function of the enzyme in the reaction is as follows:

·      Lowering the activation energy by creating an environment in which stabilized the transition state (for example, changing the shape of the substrate into the transition state conformation when it is bound to the enzyme).

·      Reduce energy transition state without changing the shape of the substrate to create an environment that has the opposite charge distribution in the transition state.

·      Provide an alternative reaction path. For example while reacting with the substrate to form enzyme-substrate complexes between.

·      Reducing the reaction entropy change leads to the substrate with the proper orientation to react. Interestingly, this entropy effect involves destabilization of the ground state and the relatively small contribution to the catalyst.

2.7  Factors Affecting Enzyme Activity

Enzyme activity is influenced by several factors, among others:

a.    Temperature

Any increase in temperature of 10 º C, the enzyme reaction rate is doubled. This applies within reasonable temperature limits. The temperature rise associated with increasing kinetic energy of the substrate and enzyme molecules. At higher temperatures, increasing the speed of the substrate molecule. So, when collided with an enzyme, a substrate molecule energy is reduced. This facilitates the substrate molecule bound to the enzyme active side. Increase in extreme temperatures can cause the enzyme constituent atoms vibrate so that the hydrogen bond is lost and the denatured enzyme. Denaturation is the destruction of three-dimensional form of the enzyme and causes the enzyme regardless of the substrate. That is, led to decreased enzyme activity, denaturation is irreversible (irreversible). Each enzyme has an optimum temperature, most of the human enzyme has an optimum temperature of 37 º C. Most of the plant enzyme has an optimum temperature of 25 º C.

b.   pH (acidity)

Enzymes are very sensitive to changes in the degree of acidity and alkalinity (pH) environment. The enzyme can be switched off when in a strong acid or strong base. In general, intracellular enzymes to work effectively in the range of pH 7.0. If the pH is raised or lowered outside the optimum pH, the enzyme activity will decline rapidly. However, there is an enzyme that has a very acidic pH optimum, such as pepsin, and slightly alkaline, such as amylase. Pepsin has an optimum pH of about 2 (highly acidic). Meanwhile, amylase has a pH optimum of about 7.5 (slightly alkaline).

c.    Inhibitors

Action of the enzyme can be blocked by other substances. Substances that can inhibit the action of the enzyme called inhibitors. These substances have a structure such as an enzyme that can fit into the substrate, or anyone has a structure such as an enzyme substrate so that any entry into the block.

d.   Activator

In addition to inhibitors, activators are also affecting the action of the enzyme. Activators are molecules that facilitate binding to the enzyme substrate. For example, chloride ions play a role in the salivary amylase activity.

2.8  Coenzyme

Coenzyme is a organic compound non-weight proteins and small molecules that may help the enzyme to work. Coenzymes are sometimes referred to as kosubstrate. This molecule is a substrate for the enzyme and do not form a permanent part of the structure of the enzyme.
Coenzyme derived from the prosthetic group, the non-protein components and strongly bound to the enzyme, such as iron-sulfur clusters, flavins or haem. Examples of the prosthetic group of enzymes that have a kind of cofactor that is widely non-protein molecules that are usually organic molecules or metal ions required by the enzyme for its activity. Presented in the following table the names of enzymes that require cofactors:

2.9  Allosteric Enzyme and Its Control

Glycolysis to glucose to pyruvic acid reshuffle undertaken by a group of enzymes (enzyme systems) that work together in a sequential circuit or system. Within this system, the first enzyme reaction product becomes the substrate for the enzyme and the enzyme product is an enzyme substrate for the next and so on until the resulting pyruvic acid. Multienzyme system can have up to 15 or more enzymes that work on a specific sequence.

In every system there is at least one pacemaker enzyme that determines the overall speed of the reaction sequence, since this enzyme catalyzes the slowest stage or stages of the pacesetter. Enzyme boosters such as this not only has a catalytic function, but also capable of increasing or decreasing the catalytic activity in response to certain cues. Catalytic activity of enzymes that is regulated through different types of molecular signals known as regulatory enzyme (enzyme regulator) is divided into an allosteric enzyme (regulator rather than covalent) and the covalent regulatory enzymes.

In some systems of multienzyme, the first enzyme or enzyme regulators (regulatory enzymes) are generally inhibited specifically by the multienzyme system end products.Therefore, the whole system works enzyme reaction rate is slowed until the concentration of the final product according to the needs of the cell. Type of inhibition is called inhibition of return. The classic example of allosteric inhibition of return is a bacterial enzyme system that catalyzes the conversion of L-threonine to L-isoleucine through the five stages of the enzyme reaction. The first enzyme is threonine dehydratase is inhibited by isoleucine, the end product of a series of five enzymes work.Although isoleucine is a highly specific inhibitor, but not isoleucine substrates bind to the enzyme threonine dehydratase, but specific binding to the other side is called the regulator. Binding of isoleucine on the regulatory enzyme threonine dehydratase nonkovalen this is so it can be addressed immediately.

Allosteric enzyme is an enzyme regulating the catalytic activity caused by increased nonkovalen of certain metabolites on the other side (control side) of the catalytic enzyme. Allosteric term comes from the Greek, namely: "allo" meaning other and "stereos" which means the room or the side. So the allosteric enzyme is an enzyme that has a side other than the catalytic side.

There are three main differences from siffat allosteric properties of the enzyme compared with the properties of the enzyme rather than regulators (enzymes in general), namely:

1.      Allosteric enzyme has both catalytic and one or more of the regulatory or allosteric binding for metabolite regulator called modulator (regulator) or effector.

2.      Allosteric enzyme molecules are generally larger and more complex with the enzyme molecule than usual. Most allosteric enzymes have two or more polypeptide chains.

3.      Allosteric enzymes usually exhibit significant deviations from classical behavior of Michaelis-Menten. Allosteric enzyme showed saturation. With excess substrate. But if the initial velocity is mapped to an allosteric enzyme substrate concentration, there was sigmoid-shaped saturation curve and not a hyperbolic substrate saturation curves in the normal enzyme.

2.10          Genetic Control of Enzyme

The presence of the enzyme by the presence or absence of a substrate divided into:

1.      Constitutive enzyme: an enzyme which is always present in the cell and is constantly produced by cells. For example, the enzymes for the glycolysis reaction path and the Krebs cycle.

2.      Adaptive inductive enzymes or enzyme: an enzyme which is produced when the existing substrate. This enzyme synthesis through enzyme induction. Substrates that stimulate (induce) to produced an enzyme called inducers. Commonly known example is the lac operon, the inducer is the sugar lactose and their indusible enzyme (the induction) is a β-galactosidase.

Enzyme activity can be controlled via two control mechanisms, namely:

a.       Through the coupling of catalytic mechanism itself is by changing the concentration of substrate or reactant, or by changing the concentration of enzyme or prosthetic groups.

b.      Through coupling with other processes, by way of regulation by ligands (molecules that can be bound to the enzyme molecule). How there are three kinds:

Ø  Activation of precursors; first precursor or metabolite of a regulatory ligand.

Ø  Control of energy-related, such as regulator ligand adenylate (ATP, ADP and AMP).

Ø  Barriers reverse flow,regulator ligand is the end product of metabolic trajectory.

2.11          Source of Enzymes

Various enzymes are used commercially comes from a network of plants, animals, and of selected microorganisms. Enzymes that are traditionally derived from plants include protease (papain, fisin, and bromelain), amylase, lipoksigenase, and certain special enzymes. From animal tissues, the enzyme that is primarily of pancreatic trypsin, lipase and enzymes for the manufacture of butter. From animal tissues, the enzyme that is primarily of pancreatic trypsin, lipase, and enzyme for the manufacture of butter. Of both plant and animal sources may arise many problems, namely: for enzymes derived from plants, other issues timbulantara seasonal variations, the low concentration and high processing costs. While the results obtained from the side of the meat industry, the enzyme may be a limited supply and no competition with other uses. Now it is clear that many of these traditional sources of enzymes are not eligible to meet the needs of the present enzyme. Therefore, the increased resources of the enzyme while the enzyme-producing microbes that are known or producing other new enzymes.

Program selection of enzyme production is very complicated, and in certain types of cultivation are used will determine the method of strain selection. It has been shown that certain strains will only produce a high concentration of enzyme on the surface or solid media, whereas the other strains respond to other cultivation techniques immersed (submerged), so selection techniques must comply with the final commercial production.

2.12          Enzyme Deficiency

A variety of metabolic disorders known to be caused by a deficiency or malfunction of an enzyme. Examples are:

·         Albino (albinism) is often caused by a deficiency of the enzyme tyrosinase, an enzyme which is essential for producing pigment cell.

·          congenital deficiency causes the disease penilketonuria phenylalanine (PKU) which if untreated will cause mental retardation in children.

·         pyruvate kinase enzyme deficiency in red blood cells (erythrocytes) will result in low energy (ATP) generated in the anaerobic oxidation, so the cells are not able to maintain the integrity of the membrane, resulting in a simple cell lysis (rupture).

·         The impact is hemolytic anemia, where there is rupture of the membranes of red blood cells.

CHAPTER III

CLOSING

3.1 Conclusion

Ø  The enzyme is a protein that serves as biokatalisator, compound increase the speed of chemical reactions in a living body.

Ø  The enzymes are classified based on the procedure name.

Ø  Mechanism of action of the enzyme can be explained through the theory and the theory padlock provisions induction.Enzyme inhibitors or inhibitors work temporarily or permanently divided into two enzyme inhibitor is a competitive inhibitor and a noncompetitive inhibitor.

Ø   Factors that influence the action of the enzyme is the temperature, pH (acidity), and inhibitor.

3.2 Advice

Ø  Hopefully this paper is useful for the readers.

Ø   If this paper is not yet included in its entirety, is expected to criticisms and suggestions.

Ø  It is not aware of the foods we eat contain a variety of enzymes are invisible to the eye, for it to overcome the enzyme can be done by enzyme supplementation or diet or pattern of applying the right foods such as reducing the consumption of fatty foods.

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Poedjiadi, Anna. 1994. Dasar-dasar Biokimia. Jakarta. Universitas Indonesia.

Saryono. 2011. Biokimia Enzim. Yogyakarta. Nuha Medika

Soendoro. 1989. Prinsip-prinsip Biokimia.Jakarta. Erlangga.