Enzymes Flashcards
are complex biological molecules,
primarily or entirely protein, that behave as
biological catalysts.
Enzymes
Some enzymes consist entirely of proteins, whereas others have nonprotein portions known
Cofactors
This may be a metal ion, such as magnesium, or an organic substance.
Cofactor
This may be a metal ion, such as magnesium, or an organic substance.
Cofactor
An organic cofactor is called a
Coenzyme
An enzyme lacking its cofactor is an
Apoenzyme
The combination of an apoenzyme and its cofactor is a
Holoenzyme
This contains an apoenzyme and a metal ion cofactor
Metalloenzyme
A tightly bound coenzyme is a
Prosthetic group
The enzyme in an inactive form is called
Proenzyme or zymogen
One of the enzymes present in the
stomach that’s responsible for the digestion of
proteins.
Trypsin
the molecule upon which an enzyme
acts
Substrate
is foundational to enzyme kinetics, describing the rate of enzyme reactions as a function of substrate concentration
Michaelis-Menten model
The isomerization of molecules
Isomerases
The joining of two molecules
Ligases or synthetases
Additions to a double bond, or the formation of a double bond
Lyases
catalyze a simultaneous oxidation and a reduction
Oxidoreductases
is to catalyze the transfer of a group from one molecule to another
Tranferase
The term that transfers an amino group
Aminotransferase
The term that transfers a phosphoryl group
Photranferase
catalyze the cleavage of a bond through the insertion of a water molecule
Hydrolases
catalyzes the hydro- lysis of a monophosphate ester
Phosphatase
catalyzes the hydrolysis of a peptide bond
Peptidase
catalyze the removal of a group
Lyases
enzymes catalyze the conversion of one isomer to another
Isomerase
catalyzes the racemization of enantiomers
Racemase
catalyzes the change of one epimer to another
Epimerase
enzymes catalyze reactions leading to the joining of two molecules in which a covalent bond forms between the molecules
Ligases
catalyzes the formation of a C-C bond
Pyruvate carboxylase
Catalyzes the formation of a C-S bond
Acetyl-CoA synthetase
is an experiment to determine an enzyme’s catalytic activity
Enzyme assays
In this, you simply measure the amount of reaction in a fixed amount of time
Fixed-time assay
In this, you monitor the progress of a reaction continuously
Kinetic assay
is where all the enzyme molecules are part of an enzyme-substrate complex
Saturation point
Michaelis-Menten equation
V= Vmax [S] / [S] + KM
the chemists that were able to propose a model that explains the kinetics of many different enzymes
Leonor Michaelis and Maud Menten
also known as a double-reciprocal plot
Lineweaver-Burk plot
The basis of Lineweaver-Burk plot comes from the manipulation of the Michaelis-Menten equation to the form
l/v = Km/Vmax x l/[S] + l/Vmax
It is the most widely used graphical technique for the determination of KM and Vmax
Lineweaver-Burk plot
are substances that decrease an enzyme’s activity
Inhibitors
Type of inhibitors that enters the active site of an enzyme and, thus, prevents the substrate from entering
Competitive inhibitors
Type of inhibitors that don’t enter the active site but instead bind to some other region of the enzyme
Noncompetitive inhibitors
Some enzymes have multiple forms known as
Isozymes or isoenzymes
Used as a digestive aid for precooked food
Amylase
Converts starch to dextrose
Amyloglucosidase
Prevents the crystallization of lactose in ice cream
Lactase
Used in the production of fructose from cornstarch
Glucose isomerase
Used in the conversion of sawdust to sugar and the production of liquid coffee concentrates
Cellulase and hemicellulase
Removes glucose from egg solids
Glucose oxidase
Stabilizes sugars in soft-centered candy
Invertase
Clarifies wine and fruit juice
Pectinase
Removes H2O2 used in the “cold pasteurization” of milk
Catalase
Added to detergents for removal of protein stains
Alcalase
Tenderizes meat
Bromelain
Produces flavor in cheese
Lipase
Whitens bread
Lipoxygenase
Tenderizes meat and stabilizes beer
Papain
Used as a digestive aid for precooked food under proteases
Pepsin
Used in cheese making
Rennin
In this form of regulation, an inactive form of an enzyme — a proenzyme or a zymogen — undergoes irreversible conver- sion to the active form, often through the hydrolysis of one or more peptide bonds.
Proteolytic activation
