enzymes and cofactors

Question 1

What is name and function of cofactor for Cytochrome P450?

Answer 1

NADPH is oxidized allowing cytochrome P450 to add oxygen to substances to make them more soluble and able to be excreted.

Question 2

Succinate dehydrogenase - cofactor, function, and e- acceptor to regenerate oxidized state?

Answer 2

FAD to FAD(2H), step in fuel metabolism (electron transport chain) from succinate to fumarate, Coenzyme Q regenerates (CoQ)

Question 3

cytochrome P450 - cofactor and function?

Answer 3

NADPH oxidized to NADP+, add oxygen to chemicals to make them more soluble and easier to excrete.

Question 4

HMG CoA reductase - cofactor and function?

Answer 4

NADPH oxidized, the rate limiting step in cholesterol biosynthesis.

Question 5

Lactate dehydrogenase - cofactor and function?

Answer 5

NAD+ gets reduced to NADH, Converts lactate into pyruvate (fuel oxidation)

Question 6

What is vitamin precursor for NADH and NADPH

Answer 6

Niacin

Question 7

Name 2 enzymes NADPH is a cofactor for

Answer 7

HMG CoA reductase (biosynthesis) and alcohol dehydrogenase (detoxification)

Question 8

What does niacin deficiency cause and what are the symptoms.

Answer 8

Pellagra - dermatitis, diarrhea, and dementia

Question 9

What is the cofactor for FMN and FAD and where is it in the diet.

Answer 9

riboflavin - dairy and eggs

Question 10

What could you expect from riboflavin deficiency?

Answer 10

cheilosis, glossitis, keratitis, seborrheic dermatitis, anemia

Question 11

Name 3 functions of ascorbic acid (vitamin C)

Answer 11

It is a redox cofactor for hydroxylase enzymes important in collagen synthesis, neurotransmitter synthesis, and oxygen sensing.
*Also a non-enzymatic anti-oxidant

Question 12

Name enzymes of collagen synthesis and what is the cofactor?

Answer 12

prolyl hydroxylase and lysyl hydroxylase. ascorbic acid.

Question 13

Describe oxygen sensing and ascorbic acid

Answer 13

HIF is hydroxylated in presence of oxygen which then marks it for degradation. If oxygen is not present HIF acts a transcription factor for anaerobic genes.

Question 14

Disease and symptoms associated with Vitamin C deficiency?

Answer 14

Scurvy - connective tissue defects such as gingival lesions, enlargement of costochondral junctions, and petechia.

Question 15

3 actions of Pyruvate dehydrogenase reaction

Answer 15

Decarboxylation: 3 carbon pyruvate  2 carbon acetate + CO2
Reduction of pyruvate and oxidation of NAD+
Transfer 2 carbon acyl group (acetate) to coenzyme A (CoASH)

Question 16

What is the function and cofactor of pyruvate dehydrogenase?

Answer 16

Reduces pyruvate to acetyl CoA with cofactor NAD+. It is the gatekeeper from the glycolysis pathway into the TCA cycle.

Question 17

Steps of pyruvate dehydrogenase?

Answer 17

1. Thiamine pyrophosphate (TTP) carbanion attacks pyruvate carbon releasing CO2.
2. Acetyl group transferred to lipoate (via lysine residue)
3. Another lipoate transfer
4. acetyl group is transferred to CoASH to make acetyl CoA
5. Electrons are transferred - first FADH2 is generated which then reduces NAD+ to NADH + H+.

Question 18

What is significance of SLC19A transporter?

Answer 18

It transports thiamine from diet (meat or beans) which is then used by thiamine pyrophophokinase to create Thiamine pyrophosphate (TTP), important in first step of pyruvate dehydrogenase reaction.

Question 19

Name 3 Thiamine deficiencies and symptoms.

Answer 19

Beriberi - by headache, malaise, peripheral neurpathy and heart failure.

Wernicke encephalopathy is characterized by confusion and mental status changes, abnormal eye movements (e.g. nystagmus), and ataxia.

Karsokoff psychosis is characterized by amnesia and confabulation, and is evident in ~80% of patients with Wernicke encephalopathy.

Thiamine responsive magaloblastic anemia syndrome is due to inherited mutations in the thiamine transporter SLC19A2. The condition is characterized by anemia, progressive deafness, and non-Type 1 diabetes.

Question 20

What is biotin?

Answer 20

It is a cofactor in carboxylase enzymes important in converting inorganic carbons to organic carbons for metabolism. ex. pyruvate carboxylase - End/first step in TCA cycle (pyruvate to oxaloacetate)

Question 21

HMG CoA reductase? cofactor and function

Answer 21

NADPH and is the rate limiting step in cholesterol synthesis

Question 22

What is vitamin precursor of NADH and NADPH

Answer 22

Niacin

Question 23

Disease caused by niacin deficiency? Symptoms?

Answer 23

Pellagra - dermatitis, diarrhea, and dementia

Question 24

Lactate dehydrogenase cofactor and function?

Answer 24

NADH, Oxidizes pyruvate to lactate

Question 25

which cofactor acts as prosthetic group

Answer 25

FMN and FAD

Question 26

What is vitamin precursor for FMN and FAD

Answer 26

riboflavin

Question 27

Succinate dehydrogenase, what is cofactor, function, and electron acceptor?

Answer 27

FAD
Fuel metabolism
Coenzyme Q (CoQ)

Question 28

Riboflavin deficiency causes what?

Answer 28

cheilosis, glossitis, keratitis, dermatitis