CLASS AND PROPERTIES OF ENZYMES Flashcards
carbohydrase, proteases and lipases are examples of?
HYDROLASE
CLASSIFICATION OF ENZYMES
OXIDOREDUCTASE
TRANSFERASE
HYDROLASE
LYASE
ISOMERASE
LIGASE / SYNTHETASE
breaking of glycosidic bonds in oligo- and polysaccs
CARBOHYDRASE
enzyme that catalyzes an oxidation-reduction reaction
OXIDOREDUCTASE
Lactate dehydrogenase is an example of?
OXIDOREDUCTASE
breaking of peptide linkages in protein
PROTEASES
breaking of ester linkages in TAG
LIPASES
Catalyzed reaction:
lactic acid + NAD = pyruvic acid + NADH + H+
LACTATE DEHYDROGENASE
enzyme that catalyzes the addition of a grp to a double bond
LYASE
increases the number of C-O bonds and/or decreases no. of C-H bonds
ORGANIC OXIDATION
removal of a group to form a double bond in a manner that does not involve hydrolysis or oxidation
LYASE
decreases the number of C-O bonds and/or increases no. of C-H bonds
ORGANIC REDUCTION
dehydratase and hydratase are examples of?
LYASE
enzyme that catalyzes the transfer of functional grp other than hydrogen frm one mol. to another
TRANSFERASE
this effects (?) the removal of components of water from double bond
DEHYDRATASE
transaminases and kinases are examples of?
TRANSFERASE
effects the addition of the components of water to a double bond
HYDRATASE
enzyme that catalyzes a hydrolysis reaction where the addition of H20 mol to a bond causes the bond to break
HYDROLASE
catalyzes the isomerization and converts it into a mol, isomeric with itself
ISOMERASE
these reactions are central to the process of digestion
HYDROLASE
- transfer of an amino group between substrates
- transfer of a phosphate group between substrates
TRANSFERASES
one reactant and one product and where isomerase are operative
ISOMERASE
- hydrolysis of ester linkages in lipids
- hydrolysis of amide linkages in proteins
- hydrolysis of sugar–phosphate ester bonds in nucleic acids
- hydrolysis of glycosidic bonds in carbohydrates
- hydrolysis of phosphate–ester bonds
HYDROLASES
enzyme that catalyzes the bonding together of two mol in one w/ the participation of ATP
LIGASE / SYNTHETASE
- removal of H2O from a substrate
- removal of CO2 from a substrate
- removal of NH3 from a substrate
- addition of H2O to a substrate
LYASES
generally energetically unfavorable and require simultaneous input of energy obtained by hydrolysis reaction where ATP turns into ADP
LIGASE / SYNTHETASE
- conversion of D isomer to L isomer,or vice versa
- transfer of a functional group from one position to another in the same
molecule
ISOMERASES
- formation of new bond between two substrates, with participation of ATP
- formation of new bond bet. a substrate and CO2, with participation of ATP
LIGASES
- oxidases
- reductases
- dehydrogenases
OXIDOREDUCTASES
- Transaminases
- Kinases
TRANSFERASES
TRUE / FALSE:
Enzymes are protein catalysts that increase the velocity of a chemical reaction, and are NOT consumed during the reaction
TRUE
- Lipases
- Proteases
- Nucleases
- Carbohydrases
- phosphatases
HYDROLASES
RNAs with catalytic activity are called _________ and are much less commonly encountered than protein catalysts
ribozymes
- dehydratases
- decarboxylases
- deaminases
- hydratases
LYASES
Enzyme molecules contain a special pocket or cleft
active site
how many percentage are active sites in the entire protein structure?
10 - 20%
Enzyme-catalyzed reactions are highly efficient, proceeding from 103–108 times faster than uncatalyzed reactions
Catalytic efficiency
- oxidation of a substrate
- reduction of a substrate
- introduction of double bond (oxidation) by formal removal of two H atoms from substrate, the H being accepted by a coenzyme
OXIDOREDUCTASES
the reactant in an enzyme-catalysed reaction
substrate
- Racemases
- Mutases
ISOMERASES
contains amino acid side chains that participate in substrate binding and catalysis
active site
- Synthetases
- Carboxylases
LIGASES
The number of molecules of substrate converted to product per enzyme molecule per second
turnover number
region of an enzyme where substrate molecules bind and undergo a chemical reaction
active site
Enzymes are highly specific, interacting with one or a few substrates and catalyzing only one type of chemical reaction
SPECIFICITY
residues that form temporary bonds with the substrate
binding site
residues that catalyse a reaction of that substrate
catalytic site
4 TYPES OF SPECIFICITY
ABSOLUTE
GROUP
LINKAGE
STEREOCHEMICAL
type of specificity where enzyme will catalyze only one reaction
ABSOLUTE
intermediate reaction species that is formed when a substrate binds to the active site of an enzyme
Enzyme–substrate complex
Catalase enzyme catalyzes only
Hydrogen peroxide (H2O2) to H2O and O2
ABSOLUTE
2 types of ESC or Models of enzyme activity
Lock and key model
Induced fit model
type of specificity where the enzyme will act only on molecules that have a specific functional group, such as hydroxyl, amino, or phosphate groups
GROUP
Only substrates with a complementary geometry can be accommodated at such a site
Lock and key model
what type of specificity is Carboxypeptidase?
GROUP
simplest type and a product of enzyme specificity
Lock and key model
the enzyme will act on a particular type of chemical bond, irrespective of the rest of the molecular structure
LINKAGE
allows for small changes in the shape or geometry of the active site of an enzyme to accommodate a substrate
Induced fit model
what type of specificity is Phosphatases?
LINKAGE
induced fit is a result of the enzyme’s flexibility; it adapts to accept the incoming substrate
Induced fit model
coenzyme is permanently associated with the enzyme and returned to its original form
prosthetic group
the enzyme will act on a particular stereoisomer. Chirality is inherent in an enzyme active site because amino acids are chiral compounds
STEREOCHEMICAL
Apoenzyme + nonprotein moiety (cofactor) = ?
holoenzyme
An L-amino acid oxidase will catalyze the oxidation of the L-form of an amino acid but not the D-form of the same amino acid
STEREOCHEMICAL
FACTORS AFFECTING ENZYMATIC ACTIVITY
A. Substrate concentration
B. Temperature
C. pH
D. Enzyme concentration
Enzymes can be divided into two general structural classes
SIMPLE
CONJUGATED
an enzyme composed only of protein (amino acid chains)
SIMPLE ENZYME
an enzyme that has a nonprotein part in addition to a protein part
CONJUGATED ENZYME
refers to the active enzyme with its nonprotein component
holoenzyme
inactive enzyme without its nonprotein moiety or the protein part of the conjugated enzyme
apoenzyme
If the nonprotein moiety is a metal ion such as Zn2+ or Fe2+
COFACTOR
a small organic molecule
COENZYME
Coenzymes that only transiently associate with the enzyme
cosubstrates