M&n Week 1: Purine And Pyrimidine Metabolism

Front 1

How are the ribonucleosides of A, G, C, and U named?

Back 1

Adenosine
Guanosine
Cytidine
Uridine

Front 2

What kind of linkage attaches the first phosphate group to the 5'-OH of the pentose sugar?

Back 2

Ester linkage

Front 3

List the compounds that contribute to the purine ring.

Back 3

1. Glutamine
2. Glycine
3. Aspartate
4. CO2
5. N10-formyl tetrahydrofolate

Front 4

The purine ring is constructed by a series of reactions that add atoms to what preformed structure?

Back 4

Ribose 5-phosphate

Front 5

What is the "activated pentose" that participates in the synthesis and salvage of purines and pyrimidines?

Back 5

PRPP

Front 6

Synthesis of Ribose 5-PO4 ---> PRPP is performed by what enzyme?

Back 6

PRPP synthetase

Front 7

How is PRPP synthase activated and inactivated?

Back 7

Activated by inorganic phosphate
Inactivated by purine nucleotides (end-product inhibition)

Front 8

Which enzyme synthesizes 5-phosphoribosylamine?

Back 8

Amidophosphoribosyl transferase

*Committed step in purine synthesis

Front 9

What compounds inhibit amidophosphoriribosyl transferase?

Back 9

AMP, GMP, and IMP
(end products of pathway)

Front 10

What compound is referred to as the "parent" purine nucleotide?

Back 10

IMP (inosine monophosphate)

Front 11

How many steps are involved in the conversion of IMP to AMP or GMP?

Back 11

2 steps

Front 12

The synthesis of AMP from IMP requires what energy source?

Which energy source is required for the synthesis of GMP?

Back 12

AMP requires GTP
GMP requires ATP

Front 13

What type of enzymes convert NMPs to NDPs and NDPs to NTPs?

What is the difference in specificity of these two types of enzymes?

Back 13

1. Nucleoside monophosphate kinases (ex: adenylate kinase)
*BASE SPECIFICE

2. Nucleoside diphosphate kinases
*BROAD SPECIFICITY

Front 14

Name two enzymes involved in the salvage pathway.

Back 14

1. ADPRT
2. HGPRT

Front 15

Which enzyme is deficient in Lesch Nyhan syndrome?

Back 15

HGPRT

Front 16

Which enzyme catalyzes the following reaction?

AMP + ATP <--> 2 ADP

Back 16

Adenylate kinase

(A nucleoside monophosphate kinase)

*Base specific

Front 17

Which enzyme catalyzes the following reaction?

GDP + ATP <--> GTP + ADP

Back 17

Nucleoside diphosphate kinase

*Broad specificity

Front 18

What is the function of ribonucleotide reductase?

What coenzyme is used for this reaction?

Back 18

Converts NDPs to deoxy-NDPs

*Thioredoxin

Front 19

What enzyme regenerates the reduced form of Thioredoxin?

Back 19

Thioredoxin reductase

Front 20

Which enzyme is responsible for maintaining a balanced supply of the deoxy-ribonucleotides required for DNA synthesis?

Back 20

Ribonucleotide reductase

Front 21

Which compound allosterically inhibits ribonucleotide reductase?

Back 21

dATP
(prevents DNA synthesis)

Front 22

How is gout definitively diagnosed?

Back 22

Aspiration of synovial fluid must reveal:
1. Needle-shaped crystals
2. Negative birefringence
3. Yellow crystals when parallel to light, blue when perpendicular

Front 23

Describe the characteristics of pseudogout crystals.

Back 23

1. Rhomboid shaped
2. Positive birefringence
3. Blue when parallel to light, yellow when perpendicular

Front 24

Which two metabolic disease are seemingly unrelated to purine metabolism, yet result in hyperuricemia that can cause gout?

Back 24

1. Von Gierke's disease (Type I glycogen storage disorder)
2. Hereditary Fructose Intolerance

Front 25

How are acute attacks of gout treated?

Back 25

Anti-inflammatory agents.
1. Colchicine
2. Predisone
3. Indomethacin

Front 26

Describe how Colchicine functions as an anti-inflammatory agent?

Back 26

Colchicine depolymerizes microtubules, thus decreasing the movement of neutrophils into the affected area

(Has no affect on uric acid levels)

Front 27

Which drugs treat gout by increasing excretion of uric acid?

Back 27

Uricosuric agents:
1. Probenecid
2. Sulfinpyrazone

Front 28

What type of drug is used to treat patients with gout who are "underexcreters?"

Back 28

Uricosuric agents:
1. Probenecid
2. Sulfinpyrazone

Front 29

What type of drug is used to treat patients with gout who are "overproducers?"

Back 29

Inhibitors of uric acid synthesis:
1. Allopurinol
2. Febuxostat

Front 30

How does allopurinol reduce the production of uric acid?

Back 30

It inhibits xanthine oxidase

Front 31

Which cells have the highest activity of adenosine deaminase?

Back 31

Lymphocytes

Front 32

Which compound provides the ribose-phosphate group for purine and pyrimidine synthesis?

Back 32

PRPP

Front 33

How is amidophosphoriribosyl transferase activated?

Back 33

By PRPP
(PRPP is both a substrate and an activator)

Front 34

List 5 enzymes involved in purine catabolism.

Back 34

1. Pancreatic nucleases (ribo and deoxynucleases)
2. Adenosine deaminase (ADA)
3. Purine 5'-nucleotidases
4. Purine nucleoside phosphorylase (PNP)
5. Xanthine oxidase

Front 35

What is the result of Hypoxanthine + PRPP? Which enzyme performs this reaction?

Back 35

IMP is formed

*HGPRT

Front 36

What is the result of Guanine + PRPP? Which enzyme performs this reaction?

Back 36

GMP is formed

*HGPRT

Front 37

What is the result of allopurinol + PRPP? Which enzyme performs this reaction?

Back 37

ALMP

*HGPRT

Front 38

What is the result of adenine + PRPP? Which enzyme performs this reaction?

Back 38

AMP

*APRT

Front 39

Which two enzymes does allopurinol inhibit?

Back 39

1. Xanthine oxidase
2. Amidotransferase