Water Soluble Vitamins Flashcards
Thiamine characteristics?
Active form: thiamine pyrophosphate (TPP)
TPP is involved in alpha-keto acids
What are the two types of thiamine transporter?
THTR 2 (low or normal concentrations, active transport)
THTR 1 (high concentration, passive)
Alcohol affects only the THTR 2 carrier mediated transport
Thiamine deficiency leads to…
Wet beri-beri (edema and CV problems)
Dry beri-beri (neurological problems)
Wernicke-Korsakoff syndrome: CNS lesions, associated with alcoholism
Riboflavin (Vitamin B2)
Is readily destroyed by sunlight
Active forms are FMN (can be reduced to FMNH2) and FAD (can be reduced to FADH2)
Riboflavin deficiency
Stomatitis (inflammation of mouth)
Cheilosis (painful cracking of corners of mouth)
Glossitis (inflammation of tongue)
Niacin
Active forms: NAD+, NADP+; serve as coenzymes in RedOx reactions
Tryptophan can make NAD, de novo
ADP ribose can help convert NAD to nicotinamide
How does niacin help lower LDL and increase HDL?
Decrease in LDL is due to noncompetitive inhibition by niacin on a liver enzyme involved in triglyceride synthesis
This decreased synthesis results in intracellular apo B degradation and decreased secretion of VLDL particles
Niacin deficiency characteristics
Pellagra: dermatitis, dementia, diarrhea (3 D’s); also caused by insufficient tryptophan
Hartnup’s dx: affects amino acid transport; an increased need for niacin may lead to its deficiency
Biotin
The enzyme biotinidase removes bound biotin from protein (a good thing!)
Deficiency of biotinidase results in increased fatty acid production; also, body becomes biotin deficient
Biotin deficiency
Caused by defects in reutilization (not diet); see biotinidase
Absence of holocarboxylase synthase enzyme causes multiple carboxylase deficiency
Panthothenic acid
Is a component of coenzyme A (CoA)
Folic acid
Consists of pteridine attached to PABA and a glutamic acid
Monoglutaminated folic acid is taken up by the reduced folate carrier (RFC) in the intestine
Formation of tetrahydrofolic acid (THF) is inhibited by…
Methotrexate, a treatment option which inhibits the dihydrofolate reductase
Also, anything affecting vit B12 production will also affect folate production
Megaloblastic anemia
Is caused by diminished synthesis of purines and thymidine, leading to the inability of cells to both divide and make DNA
Macrocytic RBCs are seen (no cell division, so the cells keep growing)
Transulfuration pathway needs vit B6
Spina Bifida
Is caused by a C -> T substitution (valine for alanine)
May account for neural tube defect