Lecture: Enzymology Flashcards by Tristan Buenvenida

Protein part of an enzyme without the cofactor necessary for catalysis

Apoenzyme

How well did you know this?

Not at all

Perfectly

An effector molecule that increases the catalytic activity of an enzyme when it binds to a specific site

Activator

How well did you know this?

Not at all

Perfectly

Substance that diminishes the rate of a chemical reaction

Inhibitor

How well did you know this?

Not at all

Perfectly

Property of a catalyst that is measured by the catalyzed rate of conversion of a specified chemical reaction produced in a specified assay system

Catalytic Activity

How well did you know this?

Not at all

Perfectly

When combined with an inactive protein called an apoenzyme, forms an active compound (complete enzyme) called a holoenzyme

Coenzyme

How well did you know this?

Not at all

Perfectly

A protein molecule that catalyzes chemical reaction without itself being destroyed, altered, consumed

Enzyme

How well did you know this?

Not at all

Perfectly

Group of related enzymes catalyzing the same reaction but having different molecular structures and physical, biochemical, and immunological properties

Isoenzyme

How well did you know this?

Not at all

Perfectly

Amount of enzyme that catalyzes the conversion of one micromole of substrate per minute under the specified conditions of the assay method

International Unit

How well did you know this?

Not at all

Perfectly

A reactant in a catalyzed reaction

Substrate

How well did you know this?

Not at all

Perfectly

Substance produced by the enzyme-catalyzed conversion of a substrate

Product

How well did you know this?

Not at all

Perfectly

Water-free cavity; specific portion of enzyme that binds on the substrate

Active Site

How well did you know this?

Not at all

Perfectly

A cavity other than the active site which may bind with regulatory molecules

Allosteric Site

How well did you know this?

Not at all

Perfectly

When bound tightly to the enzyme, the coenzyme is called

Prosthetic group

How well did you know this?

Not at all

Perfectly

Digestive enzyme originally secreted from the organ of production is called a

Proenzyme
Zymogen

How well did you know this?

Not at all

Perfectly

Apoenzyme and coenzyme forms a complete and active system known

Holoenzyme

How well did you know this?

Not at all

Perfectly

Enzyme have a rigid active site; The shape of the key (substrate) must fit into the lock (enzyme)

Emil Fisher’s / Lock and Key Theory

How well did you know this?

Not at all

Perfectly

Enzyme has a flexible active site; Based on the substrate binding to the active site of the enzyme

Kochland / Induced Fit Theory

How well did you know this?

Not at all

Perfectly

The minimum energy input needed for a reaction to occur and convert the substrates into products

Activation Energy

How well did you know this?

Not at all

Perfectly

A molecular intermediate between the substrate and its product, through which the reaction passes

Transition State

How well did you know this?

Not at all

Perfectly

Enzymes work by _ activation energy

Lowering

How well did you know this?

Not at all

Perfectly

An enzyme combines with only one substrate and catalyzes only one reaction

Absolute Specificity

How well did you know this?

Not at all

Perfectly

Enzymes combine with all the substrates in a chemical group

Group Specificity

How well did you know this?

Not at all

Perfectly

Enzymes reacting with specific chemical bonds

Bond Specificity

How well did you know this?

Not at all

Perfectly

Isoenzymes/isoforms

Stereoisomers

How well did you know this?

Not at all

Perfectly

If the reaction reached the maximum velocity, no reaction will happen.

Michaelis Menten Kinetics

Reaction rate depends only on enzyme concentration

Zero-Order Reaction

Reaction rate is directly proportional to the substrate concentration

First-Order Reaction

The rate of reaction depends on the doubled concentration of one reactant or on the product of concentration of two reactants

Second-Order Reaction

6 Enzyme Nomenclature

Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases

Catalyzes the transfer of electrons from 1 molecule (oxidant) to another molecule (reductant)

Oxidoreductases

Oxidoreductases often requires cofactors such as _

NADPH

Add hydroxyl groups to a substrate

Hydroxylases

Intramolecular oxygen is the hydrogen or electron acceptor

Oxidases

Oxidize a substrate by transferring one or more hydride ion

Dehydrogenase

Reduction of hydrogen peroxide and organic hydroperoxides

Peroxidase

Catalyze reductions

Reductase

Incorporate intramolecular oxygen into organic substrates

Oxygenase

Enzymes that catalyze the movement of a functional group from one molecule to another

Transferases

Enzymes are involved in catalyzing the transfer of phosphate groups in a process called phosphorylation

Kinase

Enzymes that catalyzes the transfer an amine group

Deaminases

Catalyzes hydrolysis (breaking of single bonds through the addition of water)

Hydrolase

Catalyzes lysis reactions that generate a double bond; type of elimination reaction but not hydrolytic or oxidative; often referred to as synthase enzymes

Lyases

Catalyzes addition reaction (substrate is added to a double bond)

Reverse Reaction

Enzymes that catalyzes structural changes within a molecule

Isomerases

Joining enzymes; responsible for catalyzing ligation of 2 molecules with the hydrolysis of a diphosphate bond in ATP or any triphosphate

Ligases

Associated with a unique numerical code designation

Enzyme Commission Numerical Nomenclature

First EC Digit of oxidoreductases

First EC Digit of transferases

First EC Digit of hydrolases

First EC Digit of lyases

First EC Digit of isomerases

First EC Digit of ligases

The temperature at which the enzyme is most active, catalyzing the largest number of reactions per second

Optimum Temperature

Most enzymes in the human body function best at about _

37 degrees Celsius

The rate of denaturation increases as the temperature increases and is usually significant at

40°C to 50°C

Looser, more random structure, and become insoluble

Denatured proteins

The process where the enzyme loses its shape and active site

Denaturation

Low temperature or freezing does not usually destroy enzymes, except:

LD – freezing at -20 degrees C CK – storing at 4 degrees C

Enzymes that work best at acidic conditions

Renin and pepsin

Enzymes that work best at alkaline conditions

Intestinal enzymes

Enzymes that work best at neutral conditions

Amylase

At pH slightly above or below the optimum, enzyme activity _

Reduces

At extreme pH conditions, enzymes are _

Denatured

Physically bind to the active site of an enzyme and compete with the substrate for the active site; reversible

Competitive inhibitors

Binds an enzyme at a place other than the active site and may be reversible in the respect that some naturally present metabolic substances combine reversibly with certain enzymes

Noncompetitive inhibitor

Another kind of inhibition in which the inhibitor binds to the ES complex

Uncompetitive inhibition

Reaction takes place at a certain period; reactions are combined; reaction proceeds for a designated time; reaction is assumed to be linear over the reaction time; the larger the reaction, the more enzyme is present

Fixed-Time (Endpoint Method)

Measured absorbance at a certain period; More advantageous than fixed time – allows monitoring of linearity

Continuous Monitoring (Kinetic Assay)

Amount of enzyme that catalyzes 1 micromole of substrate per minute

International Unit (IU/U)

1 mole of substrate per second

Katal Unit (KU)