enzymes and cofactors Flashcards
(28 cards)
What is name and function of cofactor for Cytochrome P450?
NADPH is oxidized allowing cytochrome P450 to add oxygen to substances to make them more soluble and able to be excreted.
Succinate dehydrogenase - cofactor, function, and e- acceptor to regenerate oxidized state?
FAD to FAD(2H), step in fuel metabolism (electron transport chain) from succinate to fumarate, Coenzyme Q regenerates (CoQ)
cytochrome P450 - cofactor and function?
NADPH oxidized to NADP+, add oxygen to chemicals to make them more soluble and easier to excrete.
HMG CoA reductase - cofactor and function?
NADPH oxidized, the rate limiting step in cholesterol biosynthesis.
Lactate dehydrogenase - cofactor and function?
NAD+ gets reduced to NADH, Converts lactate into pyruvate (fuel oxidation)
What is vitamin precursor for NADH and NADPH
Niacin
Name 2 enzymes NADPH is a cofactor for
HMG CoA reductase (biosynthesis) and alcohol dehydrogenase (detoxification)
What does niacin deficiency cause and what are the symptoms.
Pellagra - dermatitis, diarrhea, and dementia
What is the cofactor for FMN and FAD and where is it in the diet.
riboflavin - dairy and eggs
What could you expect from riboflavin deficiency?
cheilosis, glossitis, keratitis, seborrheic dermatitis, anemia
Name 3 functions of ascorbic acid (vitamin C)
It is a redox cofactor for hydroxylase enzymes important in collagen synthesis, neurotransmitter synthesis, and oxygen sensing.
*Also a non-enzymatic anti-oxidant
Name enzymes of collagen synthesis and what is the cofactor?
prolyl hydroxylase and lysyl hydroxylase. ascorbic acid.
Describe oxygen sensing and ascorbic acid
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.
Disease and symptoms associated with Vitamin C deficiency?
Scurvy - connective tissue defects such as gingival lesions, enlargement of costochondral junctions, and petechia.
3 actions of Pyruvate dehydrogenase reaction
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)
What is the function and cofactor of pyruvate dehydrogenase?
Reduces pyruvate to acetyl CoA with cofactor NAD+. It is the gatekeeper from the glycolysis pathway into the TCA cycle.
Steps of pyruvate dehydrogenase?
- Thiamine pyrophosphate (TTP) carbanion attacks pyruvate carbon releasing CO2.
- Acetyl group transferred to lipoate (via lysine residue)
- Another lipoate transfer
- acetyl group is transferred to CoASH to make acetyl CoA
- Electrons are transferred - first FADH2 is generated which then reduces NAD+ to NADH + H+.
What is significance of SLC19A transporter?
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.
Name 3 Thiamine deficiencies and symptoms.
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.
What is biotin?
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)
HMG CoA reductase? cofactor and function
NADPH and is the rate limiting step in cholesterol synthesis
What is vitamin precursor of NADH and NADPH
Niacin
Disease caused by niacin deficiency? Symptoms?
Pellagra - dermatitis, diarrhea, and dementia
Lactate dehydrogenase cofactor and function?
NADH, Oxidizes pyruvate to lactate
