Meaning and Characteristics of Enzymes: Enzymes are biological catalyst. They are proteins within their nature and aids in speeding up chemical action without being altered in the process of the reaction.
A catalyst could be a substance that enhances reaction without being consumed within the process.
The history of biochemistry is centered mainly on research and study of enzymes. All enzymes are proteins, and are therefore made of amino acids. However, not all proteins are enzymes. So better put; all enzymes are proteins but not all proteins are enzymes.
Enzymes are specific in action and its specificity is decided by the substrate binding site, the functional groups of the substrate or product, the functional groups of enzyme and also the physical closeness of assorted functional groups.
There are two theories that explains the Enzymes specifically.
Lock and Key Theory Model: during this model, the enzyme- substrate interaction suggests that the enzymes and substrate possess specific complementary geometric shapes that fit exactly into each other. This Lock and Key model theory was first propounded by Emil Fischar in 1894.
Koshland Induced Fit Theory: this model suggests that the site of an enzyme is flexible. The substrate induces a conformational change in coming in touch with the enzymes, in order that there is a particular alignment of susceptible bonds of the substrate with the functional groups of the enzyme’s situation.
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Trivial or common name: Trivial or common name gives no idea of source, function or reaction catalyst by the enzyme. Example: – trypsin, thrombin, pepsin.
Systematic name: Consistent with the International Union of Biochemistry (IUB), an enzyme has two parts. The primary part is the name of the substrates for the enzyme, while the secondary part is that the kind of reaction catalyzed by the enzyme. This part ends with the suffix “ase”. Example: – Lactate dehydrogenase, glucose oxidase, etc.
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Classification of Enzymes
Enzymes are classified into six different groups in line with the reaction being catalyzed. The nomenclature decided by the Enzyme Commission in 1961 (with the newest update which was made in 1992), hence all enzymes are assigned an “EC” (Enzyme Commission) number, and therefore the classification does not take organic compound sequence (homology), protein structure or chemical action under consideration.
The six classes are Oxidoreductases – EC 1, transferases – EC 2, hydrolases – EC 3, lyases – EC 4, isomerases – EC 5 and ligases – EC 6.
OXIDO-REDUCTASES – EC 1: Oxidore-ductases does the work of transferring hydrogen atoms or electrons from one substrate to a different. Oxido-reductases is additionally called oxidases, dehydrogenases or reductases. These are redox reactions, therefore an electron donor or acceptor is additionally required to finish the reaction. Samples of Oxidore-ductases are dehydrogenases, reductases, oxidases, peroxidases, oxygenases, and hydroxylases.
TRANSFERASES – EC 2: Transferases does the work of catalyzing group transfer reactions, in exclusion of oxidoreductases. Oxidoreductases are classifies under EC 1 as they transfer hydrogen or oxygen.
HYDROLASES – EC 3: The work of hydrolases is to catalyze hydrolytic reactions by adding water and then breaking the bond. They include lipases, esterases, nitrilases, peptidases or proteases.
LYASES – EC 4: The work of lyases is to catalyze non- hydrolytic removal of functional groups from substrates, often by creating a covalent bond within the product, or the reverse reaction of adding function groups across a covalent bond. This is often achieved by other means not being hydrolysis. Lyases includes decarboxylases and aldolases within the removal direction, and synthases within the addition direction.
ISOMERASES – EC 5: Isomerases does the work of catalyzing isomerization reactions, including racemization and cistran isomerizations. An example is Triose phosphate isomerase. Isomerases can produce optical, geometric or positional isomers of substrates. They catalyse intra- molecular rearrangements of a compound. E.g isomerases, racemases, epimerases, mutases.
LIGASES – EC 6: The work of ligases is to catalyze the synthesis of varied bonds, and also the breakdown of energy- containing substrates. They link two substrate together, usually with the concurrent hydrolysis of Adenodine Triphosphate (ATP) or similar energy phosphate.
Examples – aminoacyl tRNA synthetase, Ubiquitin ligases, propionyl-CoA carboxylase, etc.
Some enzymes require no chemical groups for activity while others require additional components called co- factor or co- enzyme.
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Characteristics of Enzymes
1. Enzymes are proteineous in nature: The word protein comes from Greek word, “proteios” which suggests primary. The etymology and its meaning portrays what quantity important proteins are for biological systems. Enzymes are mostly made from proteins. Proteins are polymeric in structures and are made of chain of various amino acids linked together. Most enzymes are protein contained. An exception to the current is ribozymes.
According to DM Vasudevan text on Biochemistry, within the year 1930, John Northrop (Nobel prize, 1946) crystallized variety of proteolytic enzymes from epithelial duct and proved that they are all proteins. The proteineous composition of enzymes gives the mandatory three dimensional infrastructure for reaction.
2. Enzymes are specific in action: There are basically six classes of enzymes, and every of the classes does a separate work. as an example, ligases catalyzes the synthesis of varied bonds while lyases catalyzes non-hydrolytic removal of functional groups from substrates, hydrolases hydrolyses ester, ether, peptide or glycosidic bonds by adding water and so breaking the bond.
Transferases catalyzes group transfer reactions. Isomerases catalyzes isomerization reactions, including racemization and cistran isomerization. Oxidore-ductases does the work of transferring hydrogen atoms or electrons from one substrate to a different. These are enzymes performing functions which are peculiar to them.
3. Enzymes are heat labile: Enzymes are heat sensitive. Enzymes tend to figure best at optimal temperature. They are heat labile, meaning that the temperature is kinetically unstable, rapidly cleaved and possible reformed. The term heat labile implies that something tends to loose its potency when subjected to heat.
Therefore enzymes loose their catalytic activity on an increased temperature. The temperature at which an enzyme catalyzes reaction at its highest is understood because the optimum temperature. Enzymes are denatured on warmth.
4. Enzymes are water-soluble: Certain level of water is required by enzymes so as to function efficiently. Water has the power of modifying solvent properties similarly because the soluble nature of the reactants. Water can function a substrate in an exceedingly hydrolysis as an example, and as a product of the enzymatic reaction. Enzymes are by their nature, soluble and desires water to function properly. Water helps enzymes to facilitate speed reaction.
5. Enzymes can be precipitated by protein precipitating reagents (ammonium sulfate or trichloroacetic acid).
6. Enzymes contain 16% weight as nitrogen: Nitrogen could be a vital component of amino acids of which comprises enzymes. Proteins are contained in amino acids, and every one organic compound contains protein. Each organic compound has a minimum of one nitrogen atom. The enzyme chargeable for catalyzing organic process is commonly known as Nitrogenase. Nitrogen aids within the biosynthesis of amino acids and proteins.
7. Enzymes enhance reactions by speeding up such reactions: Enzymes are biological catalysts which hastens the speed of chemical action. Enzymes fastens up chemical process, and this it achieves by lowering the energy of 1 or more specific reactions without being altered within the process.
Also by breaking down large molecules, joining small molecules to create larger ones, and by also modifying large molecules by adding small molecules. Enzymes reduces the energy required in a very chemical process, progressing from one place to the opposite.
Edeh Samuel Chukwuemeka ChMC, is a Law Student and a Certified Mediator/Conciliator in Nigeria. He is also a Developer with knowledge in HTML, CSS, JS, PHP and React Native. Samuel is bent on changing the legal profession by building Web and Mobile Apps that will make legal research a lot easier.