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Vitamins and Minerals
PANTOTHENIC ACID AND RIBOFLAVIN
September 24, 2014
Pantothenic acid (from diet)
Coenzyme A
ADP attacheshere
A thiol group(from Cysteine)is added here
Coenzyme A
HMG-CoA
Fatty acidsynthesis
Malonyl-coA
Succinyl-CoA
Citrate
TCA! 95% of ATP!PANTOTHENIC ACID
Cholesterolsynthesis
Heme synthesis
Acetyl-CoA
Heme synthesisstarts withsuccinyl coAand glycine.
(PLP)
SYNTHESIS OF ACETYL-CoA FROM PYRUVATE
TRANSFER OF ACETYL GROUP TO OXALOACETATE,TO MAKE CITRATE (FIRST STEP IN THE TCA)
Plasma concentration is about mg/L, and it’s easily filtered into the glomerular filtrate, and not completely resorbed into the proximal tubule.Trace losses of some of the B-vitamins in the urine are a common event
Since about 200 liters of GF are formed every day, about 200 mg of pantothenic acid leaves the bloodstream into the filtrate. Urinary losses of 2-7 mg/day result, so we need this in our diet. The RDA of 5 mg/day compensates for these losses.The USDA does NOT recommend fortification. Deficiency is very uncommon.
Linus Pauling Institute website: good core resourcehttp://lpi.oregonstate.edu/infocenter/vitamins/pa/
DIETARY RIBOFLAVINIS ALSO MODIFIED WITHA NUCLEIC ACID, TOMAKE THE ACTIVE FORMS.
How many vitamins requirethis kind of modification?
RIBOFLAVIN
This reduction to FADH2 adds two high-energy electrons to
the flavin group, which then donates those electrons to the ETC.
OCCURS IN THE TCA.
FADH2 is a riboflavin-dependentcomponent. The FADH2 produced
also contributes electronsfor ATP synthesis by the E.T.C.
Also has a role here
Riboflavin: role of beta-oxidation of fatty acids
Beta-oxidation of fattyacids provides about 40% of the energy in the typical American diet.
Riboflavin is essentialfor this pathway.
FATTY ACID
TCA
How many vitamins needed,to make Acetyl-CoA froma fatty acid?
C CH3
NADH+H+ NAD+
METHYLENETETRAHYDROFOLATE
METHYTETRAHYDROFOLATE
Riboflavin participates in this key step in thegeneration of active folate
Riboflavin is needed to convert oxidizedglutathione to reduced glutathione, as part
of the enzyme glutathione reductase (GSH-Red).
Levels of GSH-Red in RBC lead to a simple measurement of riboflavin status, as
will be discussed in lecture.
Similar to niacin, riboflavin is part of many biochemical pathways. This summary just
covers a few of its many functions.
What is “Enriched” flour?
According to the FDA, enriched flour must have the following quantities of nutrients per pound, to qualify:
-2.9 milligrams of thiamin
-1.8 milligrams of riboflavin
-24 milligrams of niacin
-0.7 milligrams of folic acid,
-20 milligrams of iron.
-Calcium also may be added at a minimum of 960 milligrams per pound.
A TYPICAL BAKERY LOAF (1 pound) WILL CONTAIN ABOUT 0.25-0.5 POUNDS OF FLOUR. This might contain 0.6 mg of riboflavin,which is 50% of the RDA.
Is there RIBOFLAVIN deficiency in the US?
It’s a common feature in alcoholics, but those individualsoften have MULTIPLE micronutrient deficiencies.
In general, the practice of adding riboflavin to our diet hasprotected MOST people from deficiency; but the caseswhere supplements are needed deserve careful attention.
Thyroid disease, diabetes, and use of some antidepressantsmay put people at risk; for those people, it’s important touse a multivitamin to make sure that deficiency does not occur.
A number of illnesses appear to increase micronutrient deficiency;a good argument (which could be debated) could be made that all people with a clinical disorder of any kind should receivea multi-vitamin supplement.
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