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.