L-carnitine – Flashcards

Unlock all answers in this set

Unlock answers
question
L-carnitine is a ___ ___ amino acid
answer
zwitterionic quaternary amino acid
question
the human body contains about __- __ g
answer
20-25
question
98% of the body's L-carnitine is found where?
answer
skeletal and heart muscle
question
what are the most significant dietary sources of L-carnitine?
answer
red meat and diary products
question
the average non-vegetarian American diet provides about __ to __mg/day
answer
100- 300
question
what contains little or no L-carnitine
answer
vegetables, cereals, and fruits
question
what should vegetarians make sure their diet is adequate in, to maintain normal carnitine biosynthesis?
answer
lysine, methionine, and micronutrients
question
where is L-carnitine absorbed?
answer
in the intestine using sodium dependent transport
question
what is the sodium dependent transport called used by L-carnitine
answer
organic cation transport number 2 (OCTN2)
question
Absorption of L-carnitine appears to be saturated at about a __ gram does
answer
2
question
humans can synthesize L-carnitine from the dietary amino acid __- __
answer
L-lysine
question
syntheisis of L-carnitine begins with the ___ of __- __ by __- ___ (__) to form ___
answer
methylation, L-lysine, S-adenosylmethionine, SAMe, trimethyllysine
question
the biosynthesis is accomplished by a sequence of 5 enzymes which require 5 cofactors: 1. __ 2. __ __ 3. __ 4. __ __- __ 5. ___
answer
SAMe, vitamin C, iron, vitamin B-6, niacin
question
the L-carnitine found in skeletal and cardiac muscle is transported there from the liver and kidenys because of what enzyme?
answer
gamma-butyrobetaine hydroxylase
question
the last enzymatic step in L-carnintine synthesis and is only found in liver and kidney cells
answer
gamma-butyrobetaine hydroxylase
question
carnitine is transported into skeletal muscle ___ a considerable concentration gradient via __ __ __
answer
against, sodium dependent OCTN2
question
Elimination of L-carnitine occurs primarily through the ___
answer
kidneys
question
just like amino acids, 95% of filtered L-carnitine is reabsorbed by the __ __
answer
renal tubules
question
biochemical function of L-carnitine: 1. __ __- __ __ __ __ 2. modulation of __- __ __/ __ __ __
answer
mitochondrial long-chain fatty acid transport, acetyl-coenzyme A/coenzyme A ratio
question
what is L-carnitine's primary function?
answer
involves the transformation of free long chain fatty acids into long chain acylcarnitine for subsequent transport into the mitochondrial matrix for beta-oxidation
question
L-carnitine protects cells against what? and how?
answer
toxic accumulation of acetyl-CoA compounds by acting as a reservoir for excess acetyl residues which may be generated by high rates of Beta-oxidation
question
catalyzes the rate-limiting step in transfer of long-chain fatty acids into the mitochondria
answer
Carnitine palmitoyltransferse I (CPT I)
question
what inhibits CPT I?
answer
malonyl-CoA during fatty acid synthesis
question
can ergogenic or weight loss effct chronic or acute L-carnitine supplementation?
answer
no
question
L-carnitine deficiency can be acquired as a result of what?
answer
inborn errors of metabolism
question
what can a L-carnitine deficiency result in?
answer
cardiomyopathy, congestive heart failure, encephalopthy, heptomegaly, impaired growth and development in infants and neuormuscular disorders
question
what are some pathological manifestations of chronic L-carnitine deficiency ?
answer
accumulation of lipids within skeletal muscle, cardiac muscle and liver
question
appears to decrease L-carnitine synthesis
answer
Choline supplementation
question
can decrease L-carnitine plasma concentrations
answer
anticonvulsant medications
question
what supplementation with the racemic mixture should be avoided and why?
answer
D, L-carnitine, D-carnitine is not biologically active and acts as a competitive inhibitor for L-carnitine intestinal absorption
question
deleterious and potentially toxic impurity as it leads to a functionally relevant depletion of L-carnitine in skeletal and cardiac muscle
answer
D-carnitine
question
Fatty acid accumulation can cause defects in insulin signaling and result in insulin resistance: L-carnitine facilitates the transport of __ __ into the __ for oxidation and this could reduce the lipid overload and improve __ __
answer
fatty acids, mitochondria, insulin sensitivity
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New