L8 Enzymes Flashcards by Saikaew Jurawanichkul

Enzymes work on biological molecules in 3 ways:

Anabolism
Catabolism
Rearrange atoms/ molecules (enantiomers and chiral formations

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Enzymes catalyze biological reactions in 2 ways:

Specificity and reaction rate

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Catalysts work to lower the ______ _____ of chemical reactions, thus accelerating the ______ _______

activation energy; reaction rate

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What is a substrate?

A molecule that will be worked on by an enzyme (starch is the substrate of amylase enzymes)

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Drugs and herbs fool the specificity of enzymes by causing ____ ______ of the active site

competitive inhibition

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Enzymes are made of _____ and incorporate _____ (coenzymes, vitamins, porphyrins, mineral ions) and _____

proteins; cofactors; rRNA

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(T/F) Enzymes are usually globular in shape

true son

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Tertiary structures of enzymes include at least one _____ ____ where molecules fit and are transformed

active site

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Some enzymes do not use ATP because they:

Rearrange molecules in orientation, instead of breaking and fusing bonds

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Enzyme activity is affected by external factors (6)

Presence/ absence of substrates
pH change or other ionic factors
Temp change
Availability of nutrients: ATP, cofactors, coenzymes, ions
Functionality of enzyme
Competitive inhibition of active site (drugs, herbs, etc)

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“-ase” indicates:

enzyme

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Enzymes that remove molecules or atoms from substrates

Oxidoreductases

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Enzyme that transfers functional groups from one molecule to another, such as moving a phosphate group

Transferases

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Enzyme that adds water to substreates

Hydrolases

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Enzymes that work with double bonds

Lyases

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Enzymes that change the isomeric status of a molecule

Isomerases

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Enzymes that join or release carbon bonds and requires ATP

Ligases

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What kind of pathway?

Substrate enters active site of enzyme
Enzyme changes shape as substrate binds
Catalysis
Products leave active site of enzyme

Catabolic

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A common way that drugs or other molecules stop enzymatic fx is called:

Competitive inhibition

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Orderly chain of events facilitated by different enzymes:

enzyme cascade

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Many enzymes are dependent for proper function on non-protein molecules called ________

cofactors

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An enzyme that does not have its coenzymes present and is NOT functional

apoenzyme

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An enzyme that has coenzymes present and is fully functioning:

holoenzyme

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Cofactor is a non-________ molecule that has either a tight or loose affinity to an enzyme and is required for _______ reaction

protein; enzymatic

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What are the two type of cofactors

1. Prosthetic | 2. Coenzymes

What are the 3 most common types of prosthetic groups?

Porphyrins, vitamins, metallic ions

What groups are often the limiting factors in nutrition and energy generation that can slow the overall metabolism?

Prosthetic groups (esp. porphyrins, vitamins, metallic ions)

Deficiency in vitamins and minerals slow the overall mineral metabolism in organism because:

Cellular enzymes revert back to apoenzyme status

Pyruvate dehydrogenase is an example of a:

vitamin prosthetic group

Pyruvate dehydrogenase is a _-domain enzyme used to eventually make _ _ _ from _ _

6; acetyl coenzyme A; pyruvic acid

Pyruvate dehydrogenase is made of:

1. Vitamin B1 (Cofactor thiamine pyrophosphate [TPP]) 2. Magnesium ion 3. Potassium ions

Coenzymes are called ________ b/c they act to donate a part of themselves like a substrate to a reaction happening in an active site

cosubstrates

These cofactors are rapidly consumed, renewed, and reused

Coenzymes

2 coenzymes used repeatedly in production of ATP in mitochondrion

1. NAD/NADH or nicotinamide adenine dinucleotide | 2. Acetyl coenzyme A (ACA)

_ vitamins play a vital role in energy production and can be a limiting factor in nutrition

B vitamins

NAD has one component:

Niacin- Vitamin B3

Acetyl coenzyme A has one component:

Pantothenic acid- Vitamin B5

Other important coenzymes are: (5)

ATP, lipoamine, FAD/FADH, Ubiquinone (coenzyme Q10, S-adenyl methionine (Sam-e)

ATP splits off a high energy-bonded phosphate in the _____ sites of enzymes to propel the reaction

active

Genes coding for enzymes are either ______ or ______ by gene expression factors

induced or inhibited

If the product produced by an enzyme reaches a plateau concentration, this turns off the enzyme. This is called ___ ___ ___ or __ __

Negative feedback loop | Allosteric inhibition

Enzymes can be modified by addition or subtraction of ________ groups to make the enzyme active or not (e.g. phosphorylation of enzymes will turn on breakdown of glycogen)

functional

(T/F) pH can activate/ deactivate enzyme

true

A pre-active enzyme is called a ____ or ____

zymogen or proenzyme

____ ____ is the enzyme that reduces glutathione disulfide (GSSG) to the sulfhydryl form (reduced glutathione or GSH)

glutathione reductase (GSR)

What is the most important cellular antioxidant

reduced glutathione (GSH)

For every molecule of oxidized glutathione (GSSG), __ molecules of NADPH are required to reduce GSSG to GSH

For every ____ and 2 ____ you gain 2 reduced _____molecules that can act as antioxidants scavenging reactive oxygen species (ROS) in the cell

GSSH and NADPH; GSH

In RBC, a lack of _____ and ______ will allow oxidants to damage and lyse cells, leading to anemia

NADPH and GSH

Reactive forms of oxygen, such as ______ leak from mitochondrial respiration enzymes and wreak havoc in cells

superoxide

Superoxides are:

oxygen with extra electron 02 -1

This can cause mutations in DNA or attack enzymes that make essential molecules:

superoxides

Combats superoxides:

superoxide dismutase (SOD) an enzyme that detoxifies superoxide

SOD (superoxide dismutase) ____ superoxide

dismutes (reaction where 2 equal but opposite reactions occur on two separate molecules)

SOD takes 2 molecules of superoxide, strips the extra ____ off of one, and places it on the other

electron

The first oxygen forms normal ____ and the other ends up with an extra electron. The one with extra electron picks up a ___ ____ to form hydrogen peroxide (H202)

oxygen; dihydrogen oxide (water)

Hydrogen peroxide is a toxic compound and must be ____ by an enzyme to be detoxified

catalyzed

What is the fastest enzyme discovered?

Catalase (converts hydrogen peroxide to water and 02)

SOD (superoxide dismutase) mutation is connected with __ ___ __ or __ __

amyotrophic lateral sclerosis (ALS) | Lou Gehrig's disease

A degenerative disorder that leads to selective death of motor neurons in the brain/ spinal chord leading to paralysis; occurs later in life; tenth of cases are hereditary

Amyotrophic lateral sclerosis (ALS) or Lou Gehrig's disease

A group of hemoprotein enzymes (proteins containing an iron porphyrin ring)

Cytochrome P450

2 fx of cytochrome P450

1. Oxygenate substrates | 2. Pass electrons in aerobic respiraton

Cytochromes catalyze a plethora of substrates, and so are:

nonspecific

Cytochrome P450 are found in all mitochondria, as a part of the ___ __ ___ of __ __

electron transport chain | oxidative phosphorylation

Cytochrome P450 can also be found in the lumen of __ __ in cells, performing ___ functions

endoplasmic reticulum | detoxification

Cytchromes are ____-associated proteins located either in the inner membrane (___) of mitochondria or in the ___ ___ of cells

membrane cristae ER

Cytochromes metabolize _____ of endogenous and exogenous compounds

thousands

Cytochrome P450 enzymes are present in all tissues of the body and play impt roles in: (4)

1. Hormone synthesis/ breakdown 2. Cholesterol synthesis 3. Vitamin D synthesis 4. Detox function of LV

The liver detoxifies or metabolizes drugs, toxic compounds, all foods, and metabolic products such as ____ (breakdown product of hemoglobin)

bilirubin

Many drug side effects are due to overuse or inhibition of cytochrome detoxification potential in LV ___

hepatocytes

__________ are the major enzymes involved in drug metabolism

Cytochromes

A lot of drugs can affect cytochromes by ___ or ____

induction or inhibition

Reduced dosage of medications from too rapid metabolism is called:

induction

Slow breakdown of drugs, causing overdose

Inhibition