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Biochemestry > Metabolism > Flashcards

Metabolism Flashcards

1
Q

Enzyme that converts galactose to galactose-1-phosphate

A

Galactokinase (GALK)

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2
Q

Upon GALK deficiency, which enzyme converts galactose to galactitol

A

Aldose reductase

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3
Q

Most important clinical manifestation (might be the only one) in GALK deficiency

A

Cataracts

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4
Q

Substrate with high osmotic activity that accumulates in the lens leading to cataract formation in patients with GALK deficiency

A

Galactitol

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5
Q

Intermediate substrate that is accumulated in the more serious form of galactosemia due to deficiency of galactose-1-phosphate uridyl transferase (GALT)

A

Galactose-1-phosphate

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6
Q

What are the clinical manifestations of GALT deficiency in the newborn period

A

Vomiting, lethargy, and failure to thrive

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7
Q

Deficient enzyme in Fabry disease

A

alpha-Galactosidase A

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8
Q

Accumulated substrate in Fabry disease

A

Ceramide trihexoside

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9
Q

Mode of inheritance of Fabry disease

A

X-linked recessive

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10
Q

Clinical manifestations of Fabry disease

A
  1. Neuropathy (mainly burning sensation)
  2. Angiokeratomas
  3. Hypohidrosis
  4. Can also develop cataracts!*
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11
Q

Disease that results from deficiency of glucose-6-phosphatase

A

Von Gierke disease

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12
Q

Clinical manifestations of von Gierke disease

A
  1. Hypoglycemia
  2. Lactic acidosis
  3. Hepatomegaly
  4. Hipertriglyceridemia
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13
Q

Deficient enzyme in Tay-Sachs disease

A

Hexosaminidase A

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14
Q

Accumulated substrate in Tay-Sachs disease

A

GM2 ganglioside

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15
Q

Clinical manifestations of Tay-Sachs disease

A
  1. Cherry-red spot on macula*
  2. Neurodegeneration
  3. Macrocephayl
  4. Abnormal startle reflex with acoustic stimuli
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16
Q

Deficient enzyme in Niemann-Pick disease

A

Sphingomyelinase

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17
Q

Accumulated substrate in Niemann-Pick disease

A

Sphingomyelin

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18
Q

Clinical manifestations of Niemann-Pick disease

A
  1. Neurodegeneration
  2. Cherry red spot on macula*
  3. Hepatosplenomegaly* (this is the differentiating symptom with Tay-Sachs disease)
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19
Q

Characteristic type of cells seen in the reticuloendotelial and nervous systems in Niemann-Pick disease

A

Lipid-laden cells (foam cells)

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20
Q

Branched-chain aminoacids

A

Leucine, Isoleucine, and Valine

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21
Q

Deficient enzyme in maple syrup disease

A

Branched-chain ketoacid dehydrogenase

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22
Q

Enzyme deficiency in homocystinuria

A

Cystathionine-B-synthase

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23
Q

Tetrahydrobiopterin works as a cofactor in which reactions

A
  1. Synthesis of serotonin
  2. Synthesis of tyrosine
  3. Synthesis of DOPA
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24
Q

Clinical manifestations of Gaucher disease

A
  1. Hepatosplenomegaly
  2. Osteoporosis - avascular necrosis of the femur*
  3. Pancytopenia/thrombocytopenia
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25
Q

Characteristic cell observed in Gaucher disease

A

Lipid-laden macrophage resembling crumpled tissue paper (Gaucher cell)

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26
Q

Deficient enzyme in Gaucher disease

A

Glucocerebrosidase

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27
Q

Accumulated substrate in Gaucher disease

A

Glucocerebroside

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28
Q

Deficient enzyme in metachromatic leukodystrophy

A

Arylsulfatase A

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29
Q

Clinical manifestations of metachromatic leukodystrophy

A
  • Motor symptoms (ataxia) and dementia

- Polyneuropathy

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30
Q

Accumulated substrate in metachromatic leukodystrophy

A

Cerebroside sulfate

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31
Q

Under anaerobic conditions, which enzyme regenerates NAD+ in order to keep glyceraldehyde-3-phosphate dehydrogenase working (and therefore, glycolysis)

A

Lactate dehydrogenase

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32
Q

Number of ATP produces in aerobic glycolysis per glucose molecule

A

32 net ATPs through the malate-shuttle (heart and liver) and 30 net ATPs through the G3P shuttle (muscle)

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33
Q

Main source of NADPH

A

HMP shunt (pentose phosphate pathway)

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34
Q

Rate limiting enzyme in the oxidative phase of the pentose phosphate shunt

A

Glucose-6-P dehydrogenase

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35
Q

Necessary molecule to keep glutathione reduced

A

NADPH (coming from the pentose phosphate pathway)

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36
Q

Histological difference between PK deficiency and G6PD

A

There are no Heinz bodies in PK defiency

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37
Q

In abscence of fructokinase, what enzyme is in charge of phosphorylating fructose to fructose-6-P

A

Hexokinase

*Normally, fructokinase phosphorylates fructose to fructose-1-P

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38
Q

Enzyme deficient in essential fructosuria

A

Fructokinase

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39
Q

Enzyme deficient in fructose intolerance

A

Aldolase B

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40
Q

Clinical manifestations of fructose intolerance

A
  • Lethargy, vomiting
  • Liver damage, hyperbilirubinemia, jaundice
  • Hypoglycemia
  • Hyperuricemia
  • Renal proximal tubule defect (Fanconi)
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41
Q

Metabolic pathways that are inhibited in fructose intolerance due to low phosphate

A

Glycogenolysis and gluconeogenesis

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42
Q

Diagnosis of fructose intolerance

A

Symptoms + reducing sugars in urine

*Urine dipstick will be negative because it only Works for glucose

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43
Q

Aldolase B metabolizes fructose-1-P to what 2 intermediates

A

Dihydroxyacetone-P (DHAP) and glyceraldehyde

*Both can be transformed into G3P and be used in glycolysis, glycogenesis, gluconeogenesis

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44
Q

Pyruvate dehydrogenase cofactor that is inhibited by arsenic

A

Lipoic acid

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45
Q

Pyruvate dehydrogenase cofactors

A
  1. Thiamine
  2. Lipoic acid
  3. CoA
  4. FAD
  5. NAD+

*Tender Loving Care For Nancy

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46
Q

Accumulated substrates in pyruvate dehydrogenase deficiency

A

Pyruvate gets shunted to lactate (via LDH) and alanine (via ALT)

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47
Q

Mode of inheritance of pyruvate dehydrogenase deficiency

A

X-linked

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48
Q

Clinical manifestations of pyruvate dehydrogenase deficiency

A
  • Neurologic defects (microcephaly and mental retardation)
  • Lactic acidosis
  • Increased serum alanine starting in infancy
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49
Q

Treatment for pyruvate dehydrogenase deficiency

A

*Increase intake of ketogenic nutrients (high fat, high lysine and leucine)

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50
Q

Reaction catalyzed by pyruvate dehydrogenase

A

Pyruvate + NAD + CoA = acetyl-CoA + CO2 + NADH

*Links glycolysis to TCA cycle

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51
Q

Enzyme deficient in Von Gierke’s disease

A

Glucose-6-phosphatase

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52
Q

Signs and symptoms of Von Gierke’s disease

A
  • Severe fasting hypoglycemia
  • Hepatomegaly (accumulation of glycogen in the liver)
  • Lactic acidosis
  • Hyperlipidemia
  • Hyperuricemia
  • Characteristic DOLL-LIKE FACIES (with short stature, protruding abdomen, and emaciated extremities)
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53
Q

Treatment for Von Gierke’s disease

A

Frequent oral glucose/cornstarch and avoidance of fructose and galactose

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54
Q

Deficient enzyme in Pompe’s disease

A

Acid maltase (lysosomal acid a-1,4-glucosidase with a-1,6-glucosidase activity)

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55
Q

Signs and symptoms of Pompe’s disease

A
  • Cardiomegaly and cardiac failure
  • Hepatomegaly
  • Exercise intolerance

PomPe trashes the PumP (1,4) - heart, liver, and muscle

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56
Q

Histologic finding in Pompe’s disease

A

Glycogen-like material in inclusion bodies

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57
Q

Deficient enzyme in Cori’s disease

A

Glycogen debranching enzyme (a-1,6-glucosidase)

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58
Q

Signs and symptoms of Cori’s disease

A
  • Accumulation of excessive amounts of glycogen with altered structure (DEXTRIN-LIKE in cytosol)
  • Hyperglycemia
  • Hyperlipidemia
  • Failure to thrive
  • Myopathy and cardiomyopathy

Abscence of hepatomegaly can be used to distinguish between this disease and Von Gierke’s

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59
Q

Deficient enzyme in Andersen’s disease

A

Branching enzyme

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60
Q

Signs and symptoms of Andersen’s disease

A
  • Muscle weakness (infantile hypotonia)
  • Exercise intolerance
  • Dilated cardiomyopathy and heart failure
  • Progressive liver failure and cirrhosis
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61
Q

Treatment for Andersen’s disease

A

Liver transplantation

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62
Q

Deficient enzyme in McArdle’s disease

A

Muscle glycogen phosphorylase (myophosphorylase)

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63
Q

Signs and symptoms of McArdle’s disease

A
  • Painful muscle cramps
  • Myoglobinuria with strenous excercise
  • Exercise intolerance

These patients have a SECOND WIND PHENOMENON during exercise due to increased muscular blood flow

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64
Q

Deficient enzyme in Hers disease

A

Hepatic glycogen phosphorylase

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65
Q

Signs and symptoms of Hers disease

A
  • Mild hypoglycemia
  • Hyperlipidemia
  • Hyperketosis
  • Hepatomegaly
  • Growth retardation in early childhood
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66
Q

Autosomal recessive glycogen storage diseases

A

“Very Poor Carbohydrate Metabolism”

Types 1 (Von Gierke), 2 (Pompe), 3 (Cori), 5 (McArdle)

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67
Q

Gluconeogenesis irreversible enzymes

A

“Pathway Produces Fresh Glucose”

  • Pyruvate carboxylase
  • PEP carboxykinase
  • Fructose-1,6-bisphosphatase
  • Glucose-6-phosphatase
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68
Q

Gluconeogenesis enzyme that transforms pyruvate into oxaloacetate (Malate shuttle through mitochondria)

A

Pyruvate carboxylase

*Activated by Acetyl-CoA, requires biotin and ATP

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69
Q

Gluconeogenesis enzyme that transforms oxaloacetate into PEP

A

PEP carboxykinase

*Requires GTP

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70
Q

Allosteric regulators of fructose-1,6-biphosphatase

A

(+) Citrate
(-) AMP, fructose-2,6-bisphosphate (because if this molecule increases, PFK-1 activity is initiated, and therefore the opposite reaction takes place for glycolysis)

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71
Q

Cell organelle in which G6P is contained

A

Endoplasmic reticulum

72
Q

Name the 3 substrates for gluconeogenesis

A
  • G3P (from adiposte tissue)
  • Lactate (from anaerobic glycolysis)
  • Gluconeogenic aminoacids (from muscle protein)
73
Q

Name the 2 major functions of the HMP shunt

A
  • Provide NADPH

* Provide Ribose-5-P

74
Q

Enzyme that catalyzes the oxidative (irreversible) reaction in the HMP shunt

A

Glucose-6-dehydrogenase

*Glucose-6-P to ribulose-5-P, 1 CO2 and 2 NADPH

75
Q

HMP shunt phase that results in the formation of ribose-5-P

A

Nonoxidative phase (reversible)

76
Q

Mode of inheritance of G6PD deficiency

A

X-linked recessive

77
Q

Why are there Heinz bodies in G6PD deficiency

A

Because hemoglobin denatures and precipitates, due to the presence of reactive oxygen species

78
Q

Signs and symptoms of G6PD deficiency

A

Episodic hemolysis characterized by anemia, hemoglobinuria, jaundice

79
Q

Characteristic cells observed in G6PD deficiency

A

Bite cells

*Result from phagocytic removal of Heinz bodies by splenic macrophages - “Bite into some Heinz ketchup”

80
Q

Hemolysis is precipitated in G6PD deficiency by…

A

Oxidizing agents

  • Fava beans
  • Primaquine
  • Anti-TB drugs
  • Dapsone
  • Infections (most common cause)
81
Q

G6PD deficiency provides increased resistance to what type of infection

82
Q

G6PD deficiency increases susceptibility to what type of infections

A

Catalase + infections

*Differentiate from CGD with NBT test (will be negative in the case of G6PD deficiency)

83
Q

End product of alcohol metabolism

84
Q

Enzyme that converts alcohol into acetaldehyide

A

Alcohol dehydrogenase

85
Q

Drug that inhibits alcohol dehydrogenase

A

Fomepizole

86
Q

Clinical uses of Fomepizole

A

Overdoses of methanol and ethylene glycol

87
Q

Enzyme that converts acetaldehyde into acetate

A

Acetaldehyde dehydrogenase

88
Q

Drug that inhibits acetaldehyde dehydrogenase

A

Disulfiram

89
Q

Clinical uses of Disulfiram

A

Discourage drinking

90
Q

Metabolic reactions that are favored in alcoholism due to increased NADH/NAD+ ratio

A
  1. Pyruvate to lactate (lactic acidosis)
  2. Oxaloacetate to malate (prevents gluconeogénesis and causes fasting hypoglycemia)
  3. DHAP to G3P (combines with FA to make triglycerides, leading to hepatosteatosis)
91
Q

Reversible enzyme that catalyzes the formation of lactate from pyruvate

A

Lactate dehydrogenase

92
Q

Deficient proteins in abetalipoproteinemia (and hypo-)

A

ApoB48 and B100

93
Q

Consequences of absent apoB48 and B100

A
  • Chylomicrons cannot be released into lymphatics
  • VLDL cannot be released from hepatocytes intro the bloodstream
  • Low serum TG and Ch
  • Accumulation of fat in enterocytes and hepatocytes
  • Malabsorption of vitamins A and E
94
Q

Signs and symptoms of hypolipidemias

A
  • Steatorrhea
  • Cerebellar ataxia
  • Pigmentary degeneration of the retina
  • Acanthocytes
  • Loss of night vision
95
Q

Allosteric regulators of hormone sensitive lipase

A

(-) insulin

(+) epinephrine and cortisol

96
Q

Pathogenesis of medium-chain acyl-CoA dehydrogenase deficiency (MCAD)

A

Decreased ability to break down fatty acids into acetyl-CoA

97
Q

Accumulated substrate in MCAD

A

Fatty acyl carnitines in the blood (8 to 10 carbons) AND dicarboxylic acids

98
Q

Important serologic characteristic of MCAD

A

Hypoketotic hypoglycemia and hyperammonemia

*Decreased beta oxidation in fasting increases reliance on proteolysis to supply glucose and ATP - aminoacid degradation produces ammonia that is converted to urea (this requires ATP) - with low ATP levels, activity of urea cycle decreases and ammonia builds up

99
Q

Infants or children with MCAD can be predisposed to…

A

Sudden death

100
Q

MCAD treatment

A
  • Avoid fasting
  • Increase intake of carbohydrates
  • IV glucose
101
Q

Deficient enzyme in Krabbe disease

A

Galactocerebrosidase

102
Q

Accumulated substrate in Krabbe disease

A

Galactocerebroside

103
Q

Signs and symptoms of Krabbe disease

A
  • Developmental delays in childhood
  • Peripheral neuropathy
  • Optic atrophy
  • Globoid cells
104
Q

Only X-linked recessive lisosomal storage disease

A

Fabry disease

105
Q

First enzyme of the urea cycle

A

Carbamoyl phosphate synthetase 1

*Substrate: HCO3 (CO2) + NH3 + 2ATP

106
Q

Main allosteric activator of Carbamoyl phosphate synthetase 1

A

N-acetylglutamate

*Therefore, a defect in N-acetylglutamate synthase also results in hyperammonemia

107
Q

Reaction catalyzed by ornithine transcarbamylase

A

Carbamoyl phosphate + ornithine = citrulline

108
Q

Enzyme that breaks down arginine to form urea and ornithine

109
Q

Metabolic pathway inhibited by hyperammonemia (and why)

A

An increase in NH3 leads to a depletion in alpha-ketoglutarate, inhibiting the TCA cycle

110
Q

Signs and symptoms of hyperammonemia

A
  • Tremor (asterixis)
  • Slurring of speech
  • Somnolence
  • Vomiting
  • Cerebral edema (and seizures)
  • Blurring of vision
111
Q

Pharmacologic management of hyperammonemia

A
  1. Lactulose (acidify the GI tract and trap NH4 for excretion)
  2. Antibiotics (i.e. Rifaximin, to decrease colonic ammoniagenic bacteria)
  3. Benzoate, phenylacetate, or phenylbutyrate to react with glycine or glutamine, forming products that are renally excreted
112
Q

Only urea cycle enzyme deficiency that is X-linked recessive

A

Ornithine transcarbamylase deficiency

*Most common urea cycle enzyme deficiency

113
Q

Laboratory findings in ornithine transcarbamylase deficiency

A
  • High NH4 and glutamine
  • Low BUN
  • Orotic acid in blood and urine (crystals in diaper!)
114
Q

Accumulated substrate in ornithine transcarbamylase deficiency

A

Carbamoyl phosphate

*Converted to orotic acid, as part of the pyrimidine synthesis pathway

115
Q

Mode of inheritance of carbamoyl phosphate synthetase 1 deficiency

A

Autosomal recessive

116
Q

Laboratory findings in carbamoyl phosphate synthetase 1 deficiency

A
  • High NH4 and glutamine

* Low BUN

117
Q

Deficient enzyme in classic PKU

A

Phenylalanine hydroxylase

118
Q

Cofactor needed by phenylalanine hydroxylases that, if deficient, can lead to malignant PKU

A

Tetrahydrobiopterin (BH4)

119
Q

Signs and symptoms of PKU

A
  • Mental retardation
  • Musty odor
  • Microcephaly
  • Seizures
  • Eczema
120
Q

PKU treatment

A
  • Decrease phenylalanine and increase tyrosine in diet
  • BH4 supplementation (if deficient)
  • Avoid ASPARTAME
121
Q

Aminoacid that becomes essential in PKU

122
Q

Laboratory findings in maple syrup disease

A

Increased alpha-ketoacids in the blood, especially those of leucine

*Leucine is neurotoxic

123
Q

Signs and symptoms of maple syrup disease

A
  • Urine has a caramel color and a sweet odor (maple syrup)
  • Mental retardation
  • Abnormal muscle tone
  • Ketosis
  • Coma and death
  • Vomiting and por feeding
124
Q

Maple syrup disease treatment

A
  • Restriction of isoleucine, leucine, and valine

* Thiamine supplementation

125
Q

Characteristic laboratory finding in malignant PKU

A

Hyperphenylalaninenemia with increased PROLACTIN

*As tyrosine hydroxylase also needs BH4, there are low levels of dopamine too, leading to decreased inhibition of dopamine!

126
Q

Dopamine beta-hydroxylase cofactors

A

Vitamin C and Cu2+

127
Q

Rate-limiting enzyme in heme synthesis

A

Aminolevulinate synthase

128
Q

Vitamin deficiencies that result in high homocysteine levels in the bloodstream

A
  • B12 (homocysteine methyltransferase cofactor)
  • B9 (used by the enzyme homocysteine methyltransferase to regenerate methionine from homocysteine)
  • B6 (used by cystathionine synthase to metabolize homocysteine)
129
Q

Functional difference between a kinase and a phosphorylase

A

A kinase phosphorylates using a phosphate group from a high-energy molecule (usually ATP), while a phosphorylase does not use ATP

130
Q

Functional difference between a synthase and a synthetase

A

A synthase uses an energy source, while the synthetase doesn’t

131
Q

Location of hexokinase

A

Most tissues, except liver and pancreatic beta cells

132
Q

Location of glucokinase

A

Liver and pancreatic beta cells

133
Q

Hexokinase kinetics

A
  • Low Km (high affinity)
  • Low Vmax (reduced capacity)
  • Not induced by insulin
  • Inhibited by glucose-6-phosphate
134
Q

Glucokinase kinetics

A
  • High Km (low affinity)
  • High Vmax (high capacity)
  • Induced by insulin
  • No negative feedback by glucose-6-phosphate, inhibited by fructose-6-phosphate
135
Q

Number of ATPs produced in the cytoplasms during glycolysis

136
Q

Rate-limiting enzyme of glycolysis

137
Q

Signs and symptoms of arsenic poisoning

A
  • Vomiting
  • Rice-wáter stools
  • Garlic breath
  • QT prolongation
138
Q

Electron transport chain (ETC) complex that uses NADH

139
Q

Complex 1 poisons

A

Rotenone and high dose barbiturates

140
Q

Electron transport chain (ETC) complex that uses FADH

A

Complex 2 (succinate dehydrogenase)

141
Q

Electron transport chain (ETC) complexes that serve as proton pumps

A

1, 3 and 4

142
Q

Mitochondrial location were protons accumulate to drive ATP synthesis

A

Intermembrane space

143
Q

Mechanisms of action of uncoupling agents of the electron transport chain (ETC)

A

Increase permeability of the inner mitochondrial membrane, causing a decrease in proton gradient and increase in oxygen consumption

*Net result is ATP synthesis stop and production of HEAT (because electron transport continues)

144
Q

Examples of uncoupling agents of the electron transport chain (ETC)

A
  • 2,4-Dinitrophenol (illicit use for weight loss)
  • Aspirin (overdose)
  • Thermogenin (brown fat)
  • Alcohol
145
Q

Electron transport chain (ETC) complex inhibited by Antimycin A

146
Q

Electron transport chain (ETC) complex inhibited by CO and cyanide

147
Q

Electron transport chain (ETC) complex inhibited by oligomycin

A

Complex 5 (ATP synthase)

148
Q

Classis galactosemia predisposes neonates to sepsis due to which bacteria

149
Q

Enzyme that converts sorbitol to glucose

A

Sorbitol dehydrogenase

150
Q

Sites deficient in sorbitol dehydrogenase and are therefore in danger of osmotic damage in case of sorbitol accumulation

A
  • Lens
  • Retina
  • Kidney
  • Schwann cells
151
Q

Dairy products that lactose intolerant patients can eat

A
  • Unpasteurized yogurt (contains lactobacillus)

* Cheese (contains very small amounts of lactose)

152
Q

Name the 10 essential aminoacids

A

“These Ten Valuable Aminoacids Have Long Preserved Life In Men”

Threonine, Tryptophan, Valine, Arginine, Histidine, Leucine, Phenylalanine, Lysine, Isoleucine, Methionine

153
Q

Out of the essential aminoacids, which are glucogenic

A

“I met his valentine, she is so sweet”

  • Methionine
  • Histidine
  • Valine
154
Q

Out of the essential aminoacids, which are ketogenic

A
  • Leucine

* Lysine

155
Q

Acidic aminoacids (negatively charged at body pH)

A
  • Aspartic acid

* Glutamic acid

156
Q

Basic aminoacids (no charge at body pH)

A

“His lies are basic”

  • Histidine
  • Lysine
  • Arginine
157
Q

Aminoacids that are required during periods of growth

A

Arginine and lysine

158
Q

Most common enzyme deficiency leading to malignant PKU

A

Dehydrobiopterin reductase deficiency

159
Q

Pathogenesis of cystinuria

A

Hereditary defect of renal PCT and intestinal aminoacid transporter that prevents reabsorption of cystine, ornithine, lysine, and arginine (COLA)

160
Q

Cystinuria treatment

A
  • Urinary alkalinization (eg, potassium citrate, acetazolamide)
  • Chelating agents (eg, penicillamine)
161
Q

Laboratory test used to diagnose cystinuria

A

Urinary cyanide-nitroprusside test

162
Q

How long does it take until glycogen stores are depleted and gluconeogénesis is required

A

12-18 hours

163
Q

Functional difference between lipoprotein lipase (LPL) and hormonse-sensitive lipase

A

LPL degrades TG circulating in chylomicrons and VLDLs (found on vascular endotelial surface), while hormone-sensitive lipase degrades TG stored in adipocytes

164
Q

Molecule in charge of mediating the transfer of colesterol esters from HDL to other lipoprotein particles

A

Cholesterol ester transfer protein (CETP)

165
Q

Function of apolipoprotein E

A

Mediates remntant uptake (everything except LDL)

*Present in almost every lipoprotein (except LDL)

166
Q

Function of apolipoprotein A-1

A

Activates lecithin colesterol acyltransferase (LCAT)

*Present in HDL and chylomicrons

167
Q

Function of apolipoprotein C-2

A

Lipoprotein lipase cofactor that catalyzes cleavage

*Must be present in chylomicrons and VLDL, also present in HDL

168
Q

Function of apolipoprotein B-48

A

Mediates chylomicron secretion into lymphatics

169
Q

Function of apolipoprotein B-100

A

Binds to LDL receptor

170
Q

Defective gene in abetalipoproteinemia

A

Microsomal triglyceride transfer protein (MTP) gene

171
Q

Substrates used by cystathionine synthase to produce cystathionine

A

Homocysteine and serine

172
Q

Substrate used to synthesize cholesterol

A

Acetyl-CoA

173
Q

Rate-limiting enzyme of colesterol synthesis

A

HMG-CoA reductase

*Located in the smooth endoplasmic reticulum (SER)

174
Q

Activators of HMG-CoA reductase

A

Insulin and thyroid hormones

175
Q

Inhibitors of HMG-CoA reductase

A

Statins, glucagon, and glucocorticoids

*Also negatively regulated by cholesterol

176
Q

Metabolic intermediate of colesterol synthesis that is also used for

  1. Synthesis of CoQ
  2. Synthesis of dolichol PPi for N-linked glycosylation of proteins
  3. Prenylation of proteins (eg, p21ras protein)
A

Farnesyl PPi

177
Q

Hydrophilic vitamin that is pharmacologicaly used to inhibit hormonse-sensitive lipase

Biochemestry (7 decks)

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