Enzyme (Quiz 1) Flashcards
are proteins that are catalysts of biochemical
reactions.
* Typically has a globular shape
* Complex 3-D structure
Enzyme
____ they are Biological Catalysts
- Increase the rate of reaction by ____ of activation.
- Catalyze nearly ____ the chemical reactions taking place in the cells of the body.
- Have unique three-dimensional shapes that fit the shapes of ____.
- Enzyme
- lowering the energy of activation
- all
- reactants
net energy released from splitting of lactose
activation energy without enzyme
when chemical rxn’s activation energy decreased, net energy released
activation energy with enzyme
in 1833 the first clear recognition of enzyme was made by these two people
Payen and Persoz
an alcohol precipitate of malt extract contained in a thermolabile substance that converted strach into sugar.
diastase
Common name: alpha-amylase (a-amylase)
he was the first to crystallize enzyme
J.B. Sumner (1924-1930)
there are more than ____ biochemically important enzyme catalyzed reactions
2500
they are characterized by specificity for substrates
enzyme
they modulates an enzymes activity
effectors
enumerate the different types of effectors
Activators, inhibitors, both, or depending on conditions
its size could vary from small single unit to large multiple units
enzyme
- Found in animal and plant cells
- Needed to speed up the breakdown of HYDROGEN PEROXIDE
- Breaks it down to OXYGEN and WATER
catalase
- Found in saliva and in the pancreas
- Break down enzyme
- Breaks STARCH down to MALTOSE
amylase
Synthesis enzyme (builds up)
* Builds Glucose-1-Phosphate molecules into Starch
* The formation of starch is tested using iodine solution
Potato Phosphorylase
reaction of enzyme without substrate
no reaction
enzyme + substrate
Reaction?
rxn: water + oxygen (bubbles)
liver homogenation
catalase enzyme
– high efficiency, 10³ to 10¹⁷ faster than the corresponding uncatalyzed reactions.
Catalytic Efficiency
high specificity, interacting with one or a few specific substrates and catalyzing only one type of chemical reaction.
specificity
what are the mild reaction conditions?
- 37°C,
- physiological pH,
- ambient atmospheric pressure.
part of the enzyme where the reactants bind, and where the biochemical reaction occurs
active site
- Amino acid side chains interact, metal ions,
- Various types of polar, non-polar, ionic interactions
enzyme active site
- The ____ is a region within an enzyme that fits the shape of molecules called _____
active site
substrate
- ____contains amino acid ____ that align and bind the ____.
- and it Releases products when the _____ is complete
- active site
- R group
- substrate
- reaction is complete
the substrate fit like a key in a lock, the active site is like a lock.
lock and key model
they are small nonprotein molecules (cofactors and prosthetic group)
subunits
apoenzyme + nonprotein part
holoenzyme
what are the two chemical composition of enzyme
(1) Single Protein
(2) Conjugated Protein
what are the two types of cofactor
coenzyme and prosthetic group
the protein portion, inactive part of holoenzyme
apoenzyme
it is the nonprotein portion, activator part of holoenzyme
cofactor
they are loosely bound to enzyme (non-covalently bound)
coenzyme
they are very tightly or even covalently bound to enzyme (covalently bound)
prosthetic group
forms of active enzyme with only protein
simple enzyme
forms of active enzymes that is formed by..
- protein and metal ion
- protein and organic molecule (coenzyme)
Enzyme + cofactor
An additional non-protein molecule that is needed by some enzymes to help the reaction
cofactors
are tightly bound cofactors
prosthetic groups
- Cofactors that are bound and released easily are called ____
- Many vitamins are ___
coenzymes
- Many active enzymes require a __ as cofactors
- Zn2+ cofactor for ___, stabilizes the ___ during the _____ of a peptide bond.
- Metal Ions
- carboxypeptidase
- carbonyl oxygen
- hydrolysis
- ___ catalyze the same reaction in different tissues in the body.
- ________ , which converts lactate to ___, (LDH) consists of ____ .
- isoenzymes
- lactate dehydrogenase
- pyruvate
- five (5) isoenzymes
Classification of Enzyme
- IUPAC
- EC
- Four integer EC number and a name
- Common name: usually the principal specific reactant + ___ (suffix)
- Does not follow any rule (in naming)
o ___
o ___
- -ase
- pepsin
- rhodanese
Naming Enzyme
- The name of an enzyme identifies the ____ substance, usually ends with -ase (sucrase from sucrose)
- The name also describes the ____ of the enzyme (oxidases)
- Sometimes common names are used, particularly for the ____ enzymes such as pepsin and trypsin
- Some names describe both the ___ and the ___. (alcohol dehydrogenase oxides ethanol)
- reacting substance
- function of the enzyme
- digestion enzymes
- substrate and function
- catalyze oxidation-reduction reactions
- used to convert L-Lactate (1 C bonded to O2) to Pyruvate (2 C bonded to O2) through Lactate dehydrogenase
oxidoreductases (dehydrogenases)
- catalyze group-transfer reaction, transfer groups of atoms
- transferred amino group through alanine transaminase
transferases
- catalyze hydrolysis
- used to convert pyrophosphate to phosphate (mechanism: water did chemistry to break a bond )
hydrolases
- addition/removal of a group to a double bonds without hydrolysis or oxidation
lyases
- catalyze structural change within a single molecule
- rearrangement of atoms
isomerases
___ catalyze ligation or ____ of two substrates, use ____ to combine molecules
- ligases
- joining
- ATP (Adenosine triphosphate)
Enzymes are classified according to the type of reaction they catalyze
classification of enzyme
Naming enzyme examples
- _____ catalyzes the hydrolysis of sucrose
- _____ catalyze oxidation reaction
- sucrase
- oxidases
He initiated the use of -ase in naming enzyme
Duclaux (1898)
