15 Enzymes To Know

Front 1

G6PDH

Reactant and product

Back 1

Reactant: Glucose-6-P

Product: 6-phosphogluconate

Front 2

G6PDH

cofactor

Back 2

NADP

(rxn: NADP ---> NADPH)

Front 3

G6PDH

part of what pathway?

Back 3

Hexose monophosphate shunt

Front 4

G6PDH

induced by

Back 4

insulin

Front 5

G6PDH

activated by

Back 5

NADP (decrease in NADPH/NADP ratio)

Front 6

G6PDH deficiency

inheritence

Back 6

XLR

Front 7

G6PDH

major function

Back 7

Generate NADPH for anabolic purposes (EG: FA synthesis), antimicrobial killing and protection of cells from reactive oxygen species

Front 8

Describe the role of NADPH in protecting against ROS (particularly in RBCs)

Back 8

NADPH reduces oxidized Glutathionine (G-S-S-G) back to its reduced form (2 GSH). GSH allows the enzyme Glutathionine peroxidase to breakdown H202

Front 9

G6PDH deficiency

3 key features

Back 9

-immunodeficiency (in severe disease)

- Heinz bodies

-hemolytic anemia

Front 10

G6PDH deficiency

stressors that can acute hemolytic anemia

Back 10

-ifn

-drugs (sulfas, chloroquine)

-fava beans

Front 11

G6PDH deficiency

Why can this condition lead to immunodeficiency?

Back 11

NAPDH oxidase generates bactericidal superoxide. NADPH deficiency inhibits this function.

Front 12

CGD/NADPH deficiency

How can the diagnosis be confirmed

Back 12

a NEGATIVE nitroblue tetrazolium test

Front 13

HMG CoA reductase

location

Back 13

ER

Front 14

HMG CoA reductase

activated by?

Back 14

insulin

Front 15

HMG CoA reductase


enzyme ACTIVITY is inhibited by

Back 15

-glucagon

-statins

Front 16

HMG CoA reductase
reaction

Back 16

HMG-CoA is converted to mevalonate

Front 17

HMG CoA reductase

cholesterol effect on the enzyme

Back 17

Increased hepatic cholesterol represses expression and enhances degradation

Front 18

HMG CoA reductase

How does inhibition by statin drugs decrease cholesterol levels?

Back 18

Inhibition by statins both decreases de novo synthesis and enhances hepatic clearence of serum cholesterol by increased LDLR expression

Front 19

HMG CoA reductase

statins are _________ inhibitors

Back 19

competitive

Front 20

DHFR

reaction it catalyzes

Back 20

Folate---->DHF--->THF

Front 21

DHFR

eukaryotic inhibitior

Back 21

methotrexate

Front 22

DHFR

prokaryotic inhibitors (2)

Back 22

-Trimethoprim

-pyrimethamine

Front 23

DHFR

Most important downstream consequence of inhibition?

Back 23

A block of DHFR function ultimately prevent synthesis of thymidylate (thymidylate synthase is folate dependent)

Front 24

how can ornithine transcarbamylase deficiency be distinguished from orotic aciduria

Back 24

OTCD has hyperammonia and low BUN

Orotic aciduria has a normal BUN

Front 25

Orotic Aciduria

enzymatic causes

Back 25

- orotic acid phosphoribosyltransferase deficiency

OR

- OMP decarboxylase deficiency

Front 26

UDP-Glucuronyl transferase

key reaction

Back 26

Bilirubin + glucoronide ----> bilirubin-diglucoronide

Front 27

UDP-Glucuronyl transferase

significance in neonates

Back 27

UDP-Glucuronyl transferase is the last enzyme expressed in infants. Thus, neonates have increased susceptibility to jaundice and kernicterus

Front 28

Dubin-Johnson syndrome

characterized by

Back 28

black pigment in the liver due to impaired excretion of direct bilirubin

Front 29

Crigler-Najjar syndrome

define

Back 29

a severe UDP-Glucuronyl transferase deficiency

Front 30

Gilbert Syndrome

define

Back 30

a benign UDP-Glucuronyl transferase deficiency

Front 31

gamma-glutamyl carboxylase

rxn:

Back 31

glu -----> gamma gultamic acid

Front 32

gamma-glutamyl carboxylase

function and substrate of this rxn:

Back 32

gamma carboxylation of factors II, VII, IX, X and Protein C&S generates Ca binding sites.

Front 33

gamma-glutamyl carboxylase

dependent on?

Back 33

vit K

Front 34

gamma-glutamyl carboxylase

inhibited by

Back 34

warfarin and dicoumarol

Front 35

Warfarin

does this drug inhibit in vitro clotting?

Back 35

NO, warfarin's effect (vit K reductase inhibition) prvents in vivo clotting by blocking clotting factor synthesis but has no effect on existant factors.

Front 36

gamma-glutamyl carboxylase

this reaction catalyzes what type of modification

Back 36

cotranslational modification of clotting factors

Front 37

Homocysteine methyltranferase

rxn:

Back 37

homocysteine ---> methionine

Front 38

Homocysteine methyltranferase

cofactors:

Back 38

-N5-methyl THF

-methylcobalamin (B12)

Front 39

mild homocysteinuria is associated with deficiencies is what vitamins

Back 39

folate
B12
B6 (cystathionine synthase rxn)

Front 40

mild homocysteinuria

symptoms

Back 40

-DVT
-stroke
-atherosclerosis

Front 41

how can B12 deficiency be distinguished from folate deficiency?

Back 41

B12 deficiency is associated with methylmalonic aciduria

Front 42

name the 3 "ABC" carboxylases

Back 42

(ATP, Biotin, Co2)

-propionyl-CoA carboxylase
-acetyl-CoA carboxylase
-pyruvate carboxylase

Front 43

Methylmalonyl-CoA mutase

rxn:

Back 43

Methylmalonyl-CoA ---> succinyl-CoA

Front 44

Methylmalonyl-CoA mutase

cofactor:

Back 44

adeonsylcobalamin (B12)

Front 45

Methylmalonyl-CoA mutase

deficiency results in:

Back 45

Methylmalonylic aciduria and peripheral neuropathy

Front 46

Lesch-Nyhan Syndrome

inheritence:

Back 46

XLR

Front 47

Lesch-Nyhan Syndrome

genetic cause:

Back 47

HGPRT deficiency

Front 48

Lesch-Nyhan Syndrome

symptoms:

Back 48

-spastic cerebral palsy
-self-mutilation
-hyperuricemia
-early death

Front 49

6-Mercaptopurine is activated by

Back 49

HGPRT

Front 50

Lesch-Nyhan Syndrome

pathophysiology

Back 50

Loss of the salvage pathways results in shunting of Hypoxanthine and guanine to the excretion pathway.

Furthermore, loss of feedback inhibition of PRPP admidotransferase results in additional purine synthesis.

Thus, HGPRT deficiency leads to crippling excesses of urate

Front 51

HGRPT

rxn:

Back 51

hypoxanthine/guanine -----> IMP/GMP

Front 52

Branched-chain Ketoacid DH

cofactors:

Back 52

TPP
Lipoic acid
CoA
FAD
NAD

Front 53

Branched-chain Ketoacid DH

critical in the metabolism of

Back 53

Valine
Leucine
Isoleucine

Front 54

Branched-chain Ketoacid DH

associated disease:

Back 54

maple serup urine disease

Front 55

maple serup urine disease

symptoms:

Back 55

-urine has a maple odor
-mental retardation
-abnormal muscle tone
-ketosis
-coma,death

Front 56

name the substances that enter the propionyl-CoA pathway

Back 56

(VOMIT)

Valine
Odd chain FA
Methionine
Isoleucine
Threonine

Front 57

Pyruvate DH

cofactors

Back 57

TPP
Lipoic Acid
CoA
FAD
NAD

Front 58

Pyruvate DH

rxn:

Back 58

pyruvate------> acetyl CoA

Front 59

Pyruvate DH

deficient in what population (consequence)

Back 59

alcoholics due to thiamine deficiency (results in lactic acidosis)

Front 60

Pyruvate DH

inhibited by

Back 60

acetyl-CoA

Front 61

PKU

genetic causes

Back 61

phenylalanine hyxdroxylase deficiency

OR

tetrahydrobiopterin deficiency

Front 62

Aspartame is contraindicated in what condition

Back 62

PKU

Front 63

PKU

untreated symptoms

Back 63

-pale skin and white hair

-mental retardation

-loss of motor control

-musty, mousy odor

Front 64

PKU

-pathophysiology

Back 64

elevated phenylalanine has a neurotoxic effect

Front 65

Phenylalanine hydroxylase

rxn

Back 65

phe ---> tyrosine

Front 66

MCAD

function

Back 66

oxidation of medium chain FA

Front 67

MCAD deficiency

symptoms

Back 67

-fasting hypoglycemia
- NO KETONES
-C8-10 acyl carnitines in blood
-DICARBOXYLIC ACIDEMIA

Front 68

Dicarboxylic acidemia is pathognomonic for

Back 68

MCAD deficiency

Front 69

Topoisomerase II

inhibited by what drug class in prokaryotes

Back 69

-quinolones

Front 70

Topoisomerase II
function

Back 70

relieves positive supercoiling during DNA replication by introducing negative supercoils

Front 71

Topoisomerase II

target for what drugs in eukaryotes

Back 71

etoposide
teniposide

Front 72

Excision endonuclease

function

Back 72

removal of intrastrand thymine dimers

Front 73

Xerderma pigmentosum

defective gene

Back 73

excision endonuclease

Front 74

Xerderma pigmentosum

symptoms

Back 74

extreme UV sensitivity
excessive freckling
multiple skin cancers
corneal ulcerations