Bayo-came-stray

Question 1

accelerate chemical reactions by decreasing the energy of activation of the reaction.

Answer 1

Enzymes

Question 2

is the amount of energy required to produce a transition state and bring about a reaction

Answer 2

Energy of activation (Ea)

Question 3

Classes of Enzymes

Answer 3

Oxidoreductases

Transferases

Transferases

Hydrolases

Lyases

Isomerases

Question 4

Enzymes that catalyze OXIDATIONS and REDUCTIONS

Answer 4

Oxidoreductases

Question 5

Enzymes that catalyze TRANSFER of moieties such as glycosyl, methyl, or phosphoryl groups

Answer 5

Transferases

Question 6

Hydrolases

Answer 6

Hydrolases Enzymes that catalyze HYDROLYTIC CLEAVAGE of C-C, C-O, C-N and other covalent bonds

Question 7

Enzymes that catalyze CLEAVAGE of C-C, C-O, C-N and other covalent bonds by atom elimination, generating double bonds

Answer 7

Lyases

Question 8

Enzymes that catalyze GEOMETRIC or STRUCTURAL CHANGES within a molecule

Answer 8

Isomerases

Question 9

Enzymes that catalyze joining together (Ligation) of 2 molecules in reactions coupled to the hydrolysis of ATP

Answer 9

Ligases

Question 10

As substrate binds, enzyme undergoes a conformational change that repositions amino acids in the active site and increases interactions with the substrate – Active site assumes shapes that are complementary to that of the substrate only after the substrate is bound

Answer 10

Flexible Model

Question 11

the velocity approached at a saturating concentration of the substrate

Answer 11

Vmax

Question 12

is the concentration of the substrate required to produce 1/2 Vmax

Answer 12

Km

Question 13

Relates initial velocity to substrate concentration [S] and maximum velocity

Answer 13

Michaelis Menten Equation

vi = Vmax [ S]
Km + [S]

Question 14

Derived from the reciprocal of the Michaelis Menten equation

Answer 14

Lineweaver Burk Equation

Question 15

Effects of Inhibitors on Km and Vmax

Km increases and Vmax constant

Answer 15

Competitive Inhibition

To overcome: increase concentration of substrate

Question 16

Effects of Inhibitors on Km and Vmax

Km constant and Vmax decreases

Answer 16

To overcome: reversible or irreversible depending on whether the inhibitor binds temporarily or indefinitely.

Question 17

interferes with the active site of an enzyme so substrate cannot bind

Answer 17

Competitive inhibitor

Question 18

• changes shape of the enzyme so it cannot bind to substrate

Answer 18

Non-Competitive inhibitor

Question 19

Contain “active sites”
May act as the second substrate
Recover original state at the end of the reaction •
Mostly derived from vitamins (deficiencies may result to impaired metabolism)

Answer 19

COENZYMES
Non protein organic portion of enzyme
Heat stable, low MW
Help enzymes accelerate reactions • Accept and transfer functional group

Question 20

Coenzymes that participate in transfer of H+ and electrons

Answer 20

1. NAD/NADP 2. FAD/FMN 3. Ubiquinone or Coenzyme Q 4. Tetrahydrobiopterin

Question 21

Coenzymes that participate in transfer of groups other than H+ and electrons

Answer 21

1. Transfer of acyl groups and active aldehydes, TPP, Lipoic acid, Coenzyme A
2. Amino group transfer Pyridoxal Phosphate
3. Activation and transfer of CO2- Biocytin
4. Transfer of one carbon compounds- Tetrahydrofolate
5. Transfer of Alkyl groups – Cobamide (B12) coenzyme

Question 22

Composed of a nucleotide (AMP) and a pseudonucleotide, nicotinamide
• Derived from Nicotinic Acid or Niacin
• Active site is found at C4 of the pyridine ring
• NAD is utilized by specific enzymes • Lactate dehydrogenase • Malate dehydrogenase
• NADP is involved in: Lipid and nucleic acid synthesis
• Reductive biosynthesis
• Glucose-6-PO4 dehydrogenase

Answer 22

Nicotinamide Adenine Dinucleotide

Question 23

Composed of an isoalloxazine ring
• Contains ribitol, instead of ribose
• Derived from Vitamin B2 or Riboflavin

Answer 23

Flavin Mononucleotide Flavin Adenine Dinucleotide FAD/FMN

Question 24

Ubiquinone (Coenzyme Q)
• Ubiquitous, lipid soluble coenzyme Of the electron transport chain
• Benzoquinone with side chains of Repeating isoprenoid units
• Involved in the reaction catalyzed by (Complex I) of the ETC

Answer 24

Ubiquinone (Coenzyme Q)

Question 25

• Synthesized from Biopterin. Involved in hydroxylation reactions catalyzed by: 1-Phenylalanine Hydroxylase 2- Tryptophan Hydroxylase

Answer 25

Tetrahydrobiopterin

Question 26

Derived from vitamin B1 (thiamine) • Consists of a substituted pyridine linked to thiazole ring with a terminal phosphate • Requires Mg ++ for activity • Inactivated by thiaminase found in raw fish

Answer 26

THIAMINE PYROPHOSPHATE

Question 27

3 Enzyme catalyzed reactions that require TPP

Answer 27

1. Non-oxidative Decarboxylation of Pyruvic Acid – Pyruvic acid decarboxylase 2. Transketolation – transketolase 3. Oxidative Decarboxylation of Pyruvic Acid- dehydrogenase

Question 28

>Derived from Pantothenic acid | >Participates in acyl group transfer

Answer 28

Coenzyme Composed of: § AMP linked to a pyrophosphate § Pantoic Acid + b-Alanine § Thioethanolamine Involved in reactions catalyzed by: § Fatty Acyl CoASH synthase § Pyruvate dehydrogenase Complex

Question 29

Derived from Biotin • Consists of: – Imidazole ring fused with tetrahydrothiophene – Valeric Acid • Synthesis is inhibited by Avidin, a protein in raw egg white Pyruvate • Associated with Carboxylation reactions or transfer of Carboxyl groups 1. Acetyl CoA Carboxylase 2.Pyruvate Carboxylase

Answer 29

Biocytin

Question 30

Involved in Amino Acid Reactions: ü Transamination- ü Decarboxylation- ü Racemization-

Answer 30

Transamination- Alanine transaminase Decarboxylation- Amino Acid decarboxylase Racemization- Amino Acid racemase

Question 31

Involved in one-Carbon group transfer except CO2 | Synthesis is inhibited by folate antagonists e.g. methotrexate, sulfonamides

Answer 31

Tetrahydrofolic acid

Question 32

Derived from Folic Acid • Consists of: – Substituted Pteridine – P-Amino benzoic Acid (PABA) – Glutamic Acid

Answer 32

Tetrahydrofolic acid

Question 33

1.Derived from Vitamin B12 or Cyanocobalamin 2.Consists of a tetrapyrrole ring with a central Cobalt atom

Answer 33

Cobamide Coenzyme

Question 34

Two coenzyme forms:

Answer 34

* Deoxyadenosylcobalamin (Isomerization) | * Methylcobalamin (Methyl Transferase Reaction)

Question 35

PEROXISOMES / PIPECOLATE OXIDASE

Answer 35

ZELLWEGER DISEASE

Question 36

GLUCOSE-6-PHOSPHATASE

Answer 36

VON GIERKE'S - GSD TYPE I

Question 37

LYSOSOMAL ACID MALTASE

Answer 37

POMPE'S - GSD TYPE II

Question 38

α-1,6-GLUCOSIDASE

Answer 38

CORI'S - GSD TYPE III

Question 39

CANAVAN DISEASE

Answer 39

ASPARTOACYLASE

Question 40

MUSCLE PHOSPHORYLASE

Answer 40

McArdle’s - GSD TYPE V

Question 41

TARUI’S DISEASE

Answer 41

PHOSPHOFRUCTOKINASE

Question 42

> At physiological pH (~7), >Doubly-charged species –

Answer 42

zwitterion

Question 43

At physiological pH (~7), | Can act either as acid or base –

Answer 43

AMPHOTERIC

Question 44

Major Pathway for Glucose Metabolism

Answer 44

Glycolysis Embden Meyerhoff Parnas Pathway)

Question 45

Occurs in cells with mitochondria With adequate supply of oxygen 2 molecules of NADH are formed when pyruvate is produced

Answer 45

AEROBIC GLYCOLYSIS

Question 46

Tissues without mitochondri With adequate supply of oxygen mitochondria Without oxygen NADH is reconverted to NAD + when lactate is the end product

Answer 46

ANAEROBIC GLYCOLYS

Question 47

Functions of Glycolysis

Answer 47

Tissues that depend on glycolysis as their major mechanism for ATP production: – RBC, cornea, lens, regions of the retina= they lack mitochondria – Kidney medulla, testis, leukocytes and white muscle fibers= few mitochondria - almost totally dependent on glycolysis

Question 48

WHICH OF THE FOLLOWING REACTIONS IS INHIBITED BY ITS PRODUCT? WHAT IS THE ENZYME?

Answer 48

A. GLUCOSE 6-PHOSPHATE → FRUCTOSE 6-PHOSPHATE B. GLUCOSE → GLUCOSE 6-PHOSPHATE C. FRUCTOSE 6-PHOSPHATE → FRUCTOSE 1,6-BISPHOSPHATE

Question 49

• ↓glucagon, ↑ insulin = ↑ fructose 2,6 bisphosphate = ↑ glycolysis

Answer 49

Well fed state

Question 50

↑ glucagon, ↓ insulin = ↓ fructose 2,6 bisphosphate = ↓ glycolysis

Answer 50

Starvation

Question 51

MOA: competing with inorganic phosphate as substrate for G3P dehydrogenase → complex that spontaneously hydrolyzes to form 3-phosphoglycerate • Bypassing of the synthesis and dephosphorylation of 1,3 BPG: cell deprived of energy

Answer 51

ARSENIC POISONING

Question 52

dependent on the presence if Mg or Mn) • Redistributes the energy within the 2-phosphoglycerate molecule • Phosphoenolpyruvate (PEP): contains high energy enol phosphate • Reversible • Inhibited by Fluoride

Answer 52

Enzyme: Enolase

Question 53

Potent inhibitor of ENOLASE

Answer 53

FLUORIDE

Question 54

Inhibits those enzymes which require LIPOIC ACID as coenzyme like pyruvate dehydrogenase, alpha ketoglutarate dehydrogenase

Answer 54

ARSENIC POISONING

Question 55

• 2nd most common cause of enzymatic related hemoyltic anemia • Restricted to erythrocytes, producing mild to severe hemolytic anemia Severity : depends on the degree of enzyme deficiency and on the extent to which individual’s compensate by synthesizing 2, 3 BPG • Mutant enzyme with abnormal properties

Answer 55

PYRUVATE KINASE DEFICIENCY