Enzymes: characteristics and industrial uses

• Enzymes are biological polymers, mostly proteins, that catalyze biochemical reactions and are crucial for metabolic processes within cells.
• The initial stage of metabolic processes depends on the enzymes present.
• Enzymes react with a substrate to produce products and are found in all tissues and fluids of the body.

Enzyme Characteristics

• Enzymes are highly specialized proteins, with the exception of RNA molecules called ribozymes.
• They are heat-labile and water-soluble.
• Enzymes can be precipitated using protein-precipitating reagents like ammonium sulphate and TCA.
• Enzymes are measured by their activity, not their concentration.
• Factors affecting enzyme activity include temperature, pH, and the concentration of both the enzyme and the substrate.
• Enzymes are very specific in function.

Industrial Uses of Enzymes

• Rennin is used to coagulate milk to make cheese.
• Amylase and protease are used for baking.
• Invertase, derived from yeast and lactose, is used in the food industry.
• Cellulase and amylases are used to remove waxes, oils, and starch coatings from fabrics and improve the product's appearance.
• Lipases are used in fruit juices to break down cell walls and increase yields.

Kinases, Phosphorylases, and Phosphatases

• Kinases, phosphorylases, and phosphatases have different functions.
• Kinases (Transferase E.C.2) transfer a phosphate group from an organic compound, typically ATP, to a substrate and catalyze phosphorylation.
• Phosphorylases (Transferase E.C.2) transfer a phosphate group from an inorganic compound to a substrate and catalyze phosphorylation.
• Phosphatases (Hydrolase E.C.3) remove a phosphate group by hydrolyzing a substrate and catalyze dephosphorylation.

Types of Enzymes

• Simple enzymes consist only of a protein component (e.g., pepsin).
• Conjugated enzymes (holoenzymes) are composed of a protein part (apoenzyme) and a non-protein part (cofactor).
• The apoenzyme is the inactive form of the enzyme that becomes active upon binding a cofactor.
• The cofactor is the non-protein part that acts as an activator.

Holoenzymes

• Holoenzymes equal apoenzyme plus prosthetic group.

Enzymes Simplified

• Enzymes split into simple and conjugated

Protein Components

• Protein parts (apoenzymes) are tightly bound to the enzyme, through covalent or non-covalent bonds.

Non-Protein Components

• Non-protein parts (cofactors) can be either metal ions or small organic molecules and are loosely bound metals (metals-activated enzymes) or of a prosthetic group

Prosthetic Group

• Prosthetic groups include organic co-enzymes (related to vitamins), such as NAD, FAD, NADP, pyridoxal phosphate, heme group, biotin, and folic acid.
• Prosthetic groups include inorganic tightly-bound metals (metaloenzymes), such as cobalt, manganese, copper, magnesium, iron, and nickel ions.

Holoenzymes, Coenzymes, Apoenzymes, Metalloenzymes, and Isoenzymes

• Separation of enzyme components can be achieved by electrophoresis.
• A holoenzyme consists of an apoenzyme (protein part) and one or several cofactors and represents the catalytically active form of the enzyme.
• An example is the multi-subunit complex of DNA polymerase.
• An apoenzyme consists of the protein part of an enzyme and is an incomplete enzyme less complex than the holoenzyme, representing the inactive form of the enzyme.
• An example is the catalytic components of DNA polymerase enzyme.
• Metal-activated holoenzymes have loosely bound metals on their prosthetic inorganic group.
• Metalloenzymes have tightly bound metals as their prosthetic group.
• Isoenzymes are enzymes with the same function but different structures and can be distinguished by electrophoresis

Catalyst vs Enzyme

• Catalysts are substances that increase or decrease the rate of chemical reactions but remain unchanged, whereas enzymes are proteins that increase the rate of chemical reactions by converting substrates into products.
• Catalysts have a low molecular weight, whereas enzymes have a high molecular weight and are globular proteins.
• Catalysts have two types: positive and negative, whereas enzymes have two types: activation and inhibitory enzymes.
• Catalysts consist of simple inorganic molecules, whereas enzymes consist of complex proteins.
• Catalysts include inorganic catalysts, whereas enzymes include organic catalysts or biocatalysts.

Enzyme Reactions

• Enzyme reactions are typically faster compared to catalyst reactions
• Enzymes are highly specific and produce large amounts of good residues compared to catalyst specificity which are not specific therefore end up producing residues with errors.
• Mild conditions, physiological pH & temp (Thermolabile) conditions required for Enzyme reactions whereas High temp, pressure (Thermostable) is needed for catalyst reactions
• C-C bonds and C-H bonds needed for Enzyme reactions whereas Absent in catalyst reactions
• Amylase and lipase examples of enzymes, and vanadium oxide for catalysts.
• Enzymes lower it, and catalyst lower energy requirements.

Coenzymes

• Classified according to their structural physiological features and functional (catalytic) properties
• Vitamins act as coenzymes (some)

Vitamin Coenzymes

• B1 (thiamin, thiamine pyrophosphate TPP)
• B2 (riboflavin)
• B3(niacin)
• B5 (panthothenic acid)
• B6(pyridoxine)
• B7 (biotin)
• B9 (folate (folic acid)
• B12 (cyano cobalamin)
• lupoic Coenzymes
• Quinone Coenzyme(wbiquinone

Non-Vitamin Coenzymes

• Nucleotide co-enzymes (UDP glucose, other nucleotide dervatives of Carbohydrates, alcohols, etc)
• monosaccharide phosphates (glucose 1,6-bisphate, 2,3-phospho- glycerate)
• Metalloporphyrin coenzymes (Hemes, chlorophyls)
• peptide coenzyme (glutathione)

Enzyme Notes

• Structure of B12 is similar to hemoglobin or Chlorophyll
• Turnover is defined as the number of molecules of substrate changed by one mole of enzyme per minute
• Substrates are substances upon which an enzyme acts and which is activated by the enzyme

Enzyme Locations

• Enzymes split into two types - intracellular and extracellular
• The enzymes that act inside the cell and work inside the cell are intracellular. Examples: DNA polymerase and catalase.
• The enzyme made by the cell but work in the outside of the cell are extracellular and are secreted by cells & work outside cell Examples: Digestive enzymes (pepsin, amylase) and Coagulation enzymes
• Endo enzymes referred to as intracellular and Exo enzymes are extracellular.
• Intracellular are more difficult to isolate, and extracellular are easier to isolate
• Intracellular account for the majority of enzymes and Extracellular account for the minority of enzymes,
• Intracellular enzymes undergo intracellular digestion whereas Extracellular enzymes undergo extracellular digestion
• intracellular enzymes breakdown Large polymers into smaller chain of monomers whereas Extracellular enzymes act on the end of the polymer to breakdown its Monomers one at a time

Zymogens

• Zymogens are inactive form of enzyme also known as proenzyme
• Zymogen activation mostly by Proteolytic activation
• They are activated by shipping the bonds between two or more amino acids as well as by enzymes changes its 3d confirmation & active site is freed
• Activation examples include fibrinogen converting to thrombin and eventually to fibrin

Zymogens and Enzymes

• Zymogens activated by environment e.g.: PH. change examples include pepsinogen becoming pepsin)
• Zymogens are activated by auto activation such as pepsthogen becoming pepsin
• Several types of enzyme activation include zymogen, metals, allosteric, and covalent

Enzyme Activation

1. Activation of zymogen
2. Activated by metals and increases affinity to substrate
3. allosteric activation by substances bind to allosteric site causing activation
4. Covalent activation causes chemical group is added or removed

Enzyme Classification and Nomenclature

• Allows identification of enzymes by the reaction they catalyse
• Relies on a numerical system to class enzymes in groups according to the type
• Systematic naming describes the chemical reaction involved and trivial names

Enzyme Naming

1. give no indication of the function of the enzyme with trivial names
2. A number of generic words indicating reaction types may be used in recommended names not in systematic names such as the substrate and the type of reaction

Substrate-Depending

• Substrate depending on the names of the substrates of the chemical reaction
• Example reactions include L-lactate+NAD+ resulting in oxidoreductase

Chemical Nature-Depending

• The name depends on the nature of the chemical reaction with and -ase ending
• Example hydrolase for hydrolysis

Enzyme Organization

1. OxidoReductases
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases or synthetases

Enzymes Listed

The enzyme Oxidoreductase catalyzes the oxidation reaction where the electrons tend to travel from one form of a molecule to the other.

• The Transferases enzymes assist in the transportation of a functional group among acceptors and donor molecules.
• Hydrolases are hydrolytic enzymes, which catalyze the hydrolysis reaction by adding water to cleave the bond and hydrolyze it.
• Lyases add water, carbon dioxide or ammonia across double bonds or eliminate these to create double bonds.
• Isomerases catalyze the structural shifts present in a molecule, thus causing the change in the shape of the molecule.
• Ligases are known to charge the catalysis of a ligation process.