RIBO-flavor Flashcards
What makes up Riboflavin
Isoalloxazine + Ribityl side chain
What is the active form of Riboflavin?
The cofactors:
- FMN
-FAD
What is required for the conversion of Riboflavin to FMN? FAD?
FMN requires Zn & ATP
FAD requires Mg & ATP (you get PP)
What regulates the conversion of FMN and FAD
Thyroid hormone
What is the main element FMN & FAD carry ?
2 H-atoms
What is the metabolic roles of B2
Energy production (TCA,ETC,B-ox)
Regulation of redox statis
Detoxification (FMOs)
Conversion of vitamins (B6 and Folate)
Syn of Niacin from typtophan
Where would you find B2 in TCA cycle
PDH (E3)
a-ketoglutarate to succinyl-coa
Succinate to fumarate (succinate dehydrogenase)
Describe the role of B2 in ETC
Complex 2 (succinate to fumarate)
Complex 1 (NADH to NAD)
Which step in B-ox requires B2
Acyl-CoA to trans-2 Enoyl-CoA
Describe B2 absorption into the enterocyte
Enters as a FMN/FAD protein
Gastric acid + Intestinal proteases convert to FMN/FAD
FMN-phosphatase + PAD-pyrophosphatase convert to Riboflavin
[Low] RFT1&2
[high] >12 it can diffuse
How is B2 metabolically trapped
When converted to FMN via RFK then to FAD via FADS
- Some FMN and all FAD is trapped
What forms of B2 are able to travel in the plasma
FMN and riboflavin
Where is the highest concentration of B2 found
little storage, highest in the liver
(1/3 FAD)
What would reflect dietary intake of riboflavin?
Urinary excretion
little is stored, rapidly excreted two hours after ingestion
limited accuracy
which form of riboflavin is most found in food?
2/3 as FAD
Out of the products listed which would give me 1/3 of the RDA for B2: green leafy veg, enriched flour, meat, dairy and eggs?
Dairy and eggs
Bioavailability is related to digestibility of food
Why might a vegetarian have better riboflavin status than a meat-based diet?
Riboflavin can be syn by bacteria in the large intestine and syn increases in veg diets
RDA? UL?
RDA: 1mg
UL: none set
What is the FAD effect?
A serum concentration test of glutathione reductase - if an increase in FAD when added would show deficiency
A:<20
M:20-40
D:>40
Ariboflavinosis
Deficiency: stunted growth, lack of energy, cheilosis & glossitis, angular stomatitis, skin lesions, corneal vascularization
Why is it hard to diagnose Ariboflavinosis
similar deficiencies as B6 (pyridoxine) because active form requires FMN
With which other nutrients would you see a B2 deficiency?
Iron - conversion of Fe3-Fe2
Folate - conversion of oxidized folate
Which populations are at risk for folate deficiency?
Low intake (Elderly/China/Wherever lacks dairy&meat)
Pregnancy
Disease states: (thyroid, diabetes, hyperbilirubinemia)
