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Are catalytic proteins that increase the biological reactions
Enzymes
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Consists only of a polypeptide chain
Simple enzymes
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Protein portion is inactive without a cofactor
Conjugated proteins
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3 parts of an active enzyme
- 1.) Apoenzyme- protein portion of the enzyme, inactive
- 2.) holoenzyme- product of Apo+ Cofactor (active protein)
- 3.) Cofactors/coenzymes- inorganic metal ions derived from B vitamins
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Thiamine (B1)
Thiaminepyrophosphate- coenzyme for decarboxylation reactions
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Riboflavin (B2)
coenzymes of Flavinadeninedinucleotide and Flavinmononucleotide
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Niacin (B3)
coenzyme of Nicotinamide adenine dinucleotide & Nicotinamide adenine dinucleotide phosphate
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Pyridoxine (B6)
Pyridoxal phosphate- coenzyme for aa and lipid metabolism
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Folic acid (B9)
Tetrahydrofolate- coenzyme for aa and nucleic acid metabolism
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Cobalamin (B12)
cobamide-coenzyme for carboxylation reactions
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Pantothenic Acid (B5)
Coenzyme A
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Vit. C (ascorbic acid)
coenzyme; antioxidant
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Catalyzes an oxidation reaction
Oxidase
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Dehydrogenase
removes hydrogen atoms
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Sucrase
hydrolyzes glycosidic bond in sucrose
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Hydrolyzes ester bonds in lipids
Lipase
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Known enzymes with "in"
- Papain- found in papaya
- Rennin- found in milk
- Pepsin and trypsin- catalyze hydrolysis of proteins
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Oxidoreductase
- Oxidation (Oxidases)
- Remove hydrogen (Dehydrogenases)
- Add hydrogen (Reductases)
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Transferases
- Transfer of amino groups (Transaminases)
- Transfer of phosphate (Kinases)
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Hydrolases
- -Hydrolyze peptide bonds (peptidases)
- - Hydrolyze ester bonds in triglycerides (Lipases)
- - Split glycosidic bonds in amylose (Amylase)
- - Hydrolyze phosphate groups (Phosphatase)
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Lyases
- -Remove CO2 (Decarboxylases)
- - Rrmove H2O (Dehydrases)
- - Remove NH3 (Deaminases)
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Isomerases
- -convert cis to trans; ketose to aldose (Isomerases)
- - convert D- to L-isomer (Epimerases)
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Ligases
- -combine two molecules (synthetases)
- - add CO2 to a substrate (carboxylases)
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What is Enzyme-substrate complex?
- - All enzymes are globular proteins
- -Each has a unique 3d shape that recognizes and binds susbtrate
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Explain the enzyme-substrate complex process
- Step 1: Mu bind and substrate sa enzyme
- Step 2: Ma form na ang enzyme-substrate
- Transition state: Maconvert ang substrate into product
- Step 3: Mahimong enzyme-product
- Step 4: Mag buwag ang enzyme ug product
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Lock and key model
Pair ang enzyme ug substrate (murag yabi ug kandado)
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Induced Fit
after mu bind ang substrate sa enzyme, mag adjust ang shape sa enzyme for the substrate
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Is the ability of an enzyme to bind only one, or a very few substrates and thus catalyze only a single reaction
Enzyme specificity
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An enzyme catalyzes the reaction of only one substrate; IF the aa attached mistakenly, it'll produce a nonfunctional protein
Absolute specificity
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An enzyme that catalyzes processes involving similar molecules containing the most functional group has group specificity
Group Specificity
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Catalyzes the formation or breakage of bonds, ex. Lipase (ester bonds)
Linkage specificity
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An enzyme that can distinguish one enantiomer from the other
Stereochemical specificity
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Factors affecting Enzyme
- 1.)Temperature- are rapidly destroyed if the temp. rises above 37 degrees celsius
- 2.)pH- Enzyme functions efficiently at pH 7
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Enzyme Concentration
As the enzyme concentration is increased, the reaction rate increases, since more substrate molecules can undergo reaction
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Regulation of Enzyme
Enzyme activity is often regulated by the cell to conserve energy
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Active sites that can be altered by binding of small molecules
Allosteric enzymes
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2 types of allosterism
- Negative allosterism- converts the active site to inactive configuration
- Positive allosterism- converts the active site to active configuration
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To avoid waste of energy the cell uses _____ in which the product can shut off the entire pathway for its own synthesis
Feedback Inhibition
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Proenzymes
- another means of regulating enzyme activity involves the production of inactive form of enzymes.
- 1.) Pepsin- if only there is food (active)
- 2.) Pepsinogen-if walay food (inactive)
- gikan cells of the stomach
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Another mechanism the cell can use to turn an enzyme on or off
Protein Modification
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Glycogen Cycle Explained
- Basta nagkaon: Glycogen Phosphorylase- Off
- Glycogen Synthase- On
- Basta wala nagkaon: Glycogen Phosphorylase-On
- Glycogen Synthase-Off
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Chemicals can bind to enzymes and either eliminate or drastically reduce their catalytic abilities.
Inhibition of Enzyme Activity
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Irreversible Inhibitors
- - Involves binding of the inhibitor to one of the R groups of an amino acid in the active site.
- - It blocks the active site binding so that the enzyme substrate-complex cannot form
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Reversible, Competetive Inhibitors
- This inhibition is competitive because the inhibitor abd the substrate compete for binding to the enzyme active site
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Reversible, non competitive
- Dili mu bind sa active site, pero i change niya ang shape sa active site. And because of that dili ka bind ang substrate
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Methanol poisoning and PABA explained
If naa methanol poisoning pa imnon ug ethanol, if daghan ang ethanol wala chance ang methanol na mu bind sa active site. Same situation sa PABA if the sulfa drug is present and mas daghan, mas mu bind ang sulfa sa enzymes in which dili dayun ka synthesize ug folic acid, and that mamatay ang bacteria.
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Uses of Enzyme in medicine Explain.
Enzymes are useful in blood testing, In blood serum analysis. It provides a lot of information about a patient's medical condition. Ex., when an organ is damaged it releases enzymes into the bloodstream which is detected by blood tests
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Enzymes, Nerve Agent & Poisoning
Acetylcholinosterase, which catalyzes the hydrolysis of the acetylcholine that serves as the chemical messenger. If acetylcholine remains at the neuromuscular junction it will continue to stimulate the muscle contraction. the AchE will destroy Ach
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