Topic 3. Enzymes Flashcards
most enzyme shape
globular
enzymes end in the suffix?
‘ase’
applications in biotechnology (4)
- added in animal feed to improve digestion
- clarifying wine
- theraputic drugs
- enzyme inhibitor drugs or poisons
fermentation is caused by
yeast secretion not necessarily living yeast cells.
The variety of reactions that enzymes catalyse can be divided into just six (6) main classes
- Oxidoreductases
- Transferase
- Hydrolases
- Lyases
- Isomerase
- Ligases
these enzymes catalyse oxidation/reduction reactions and this might involve addition/removal of hydrogen atoms, and hence these enzymes are also called dehydrogenases, oxidases, oxygenases, peroxidases, etc. (e.g. lactate dehydrogenase)
Oxidoreductases
These enzymes catalyse transfer of functional groups between donor and acceptor molecules (e.g. alanine aminotransferase and aspartate aminotransferase).
transferase
These enzymes catalyse reactions that involve addition of water (e.g. phenylalanine hydroxylase).
Hydrolases
These enzymes catalyse reactions that involve creation of bonds and can be done by adding water, carbon dioxide, ammonia, etc. (e.g. pyruvate decarboxylase).
Lyases
These enzymes catalyses isomerisation (shifts from one isomer to another) e.g. L and D isomers. Mutases shift chemical groups in isomerisation. (e.g. mutarotase).
Isomerase
Catalyses reactions in which two chemical groups are joined. They are also called synthetases. (e.g. glutamine synthetase).
Ligases
Amylases
Breaks down starch into maltose and glucose which can then be fermented by yeast, used in the brewing industry / beer production. Cleaves a1-4 bond.
Pectinases
Breaks down pectin, an insoluble carbohydrate found in fruits, thus they can be used to clarify fruit juice and wine.
Invertase
Converts (hydrolyses) the sugar sucrose into x1 glucose and x1 fructose molecule. used in the production of confectionary
Proteases
Breaks down proteins, used to tenderise meat, used in meat processing
Lipases
Breaks down lipids (fats and oils), used for foam stabilisation in a variety of food production processes.
Site on an enzyme where the substrate binds to?
Active site
Because enzymes increase the rate of a chemical reaction, the rate of an enzyme-catalysed reaction is normally referred to as its
Enzyme activity
Specific Activity of an enzyme.
expresses enzyme activity with respect to total protein.
Examples of enzymes used in agriculture biotechnology (4)
Chymosin - making cheese
Phosphotases - phosphorus cycle in the soil and plant growth. They hydrolyse phosphates and make phosphorus in the soil available to plants.
Pectin lyase enzyme - breaks down pectin, preventing hazy wine.
Polygalaturonase - tomato carbohydrate breakdown enzyme (naturally occurring)
Xylanase and it’s use in agriculture
Used in poultry (egg) production by ways of adding this enzyme to the feed, increasing the guts ability to digest nutrients in the feed. Increases availability of starch, protein, P and Ca. Chicken and pigs Don’t have a rumen, unable to digest cellulose etc.
Enzyme which Releases phosphorus in animal feed production from phytate?
Phytases
Phytase, how it works;
60-80% of the mineral P in plant feed for poultry is locked up as phytate. Phytase is an enzyme which breaks down the phytate into a usable P form. Not needed for animals with rumens as bacteria in the rumen emit enough Phytase which efficiently breaks down phytate naturally. This saves P fert prices.
Chymosin how it works
Casein contains phenylalanine and methionine amino acids joined together by peptide bonds. Chymosin specifically digests the peptide bonds between the two amino acids. This results in para-caesein chains which are hydrophilic and form a clot with ca2+ ions in the milk.
Michael is constant (Km)
Km is defined as [S] which yields 1/2 the maximum velocity of a reaction. You can determine this constant by running experiments for a different set of [S] and plot the Product formed per unit of time.
