B12 & Folic Acid

Question 1

S-Adenosyl-Methionine

Answer 1

methyl group donor

Used in Synthesis:

• epinephrine
• creatine
• PhC

after donating methyl group
SAM > homocysteine

Question 2

B12 Deficiency

Answer 2

accumulaiton of homocysteine

• damages blood vessels, risk of thrombosis
• fibrosis and calcification of atherosclerotic plaques

trapping of THF in methyl-THF form

• decrease formation of other THF derivative
• impairs NT, DNA, RNA synthesis

accumulation of abnormal (odd-chain) FA’s
-neurological effects

methylmalony aciduria

megoblastic anemia
tingling sensation in hands and feet, inablity to walk
psychiatric disturbances
urinary incontinence

pernicious anemia (lack of Intrinsic Factor)
vegan diet
gastric resection
chronic pancreatitis 
malnutrition 

takes years to develop

Question 3

Folate deficiency

Answer 3

megablastic anemia

accumulaiton of homocysteine

• damages blood vessels, risk of thrombosis
• fibrosis and calcification of atherosclerotic plaques

FluGlu accumulation (histidine metabolisis product in absence of folate)

deficiency important in pregnancy and conception
-neural tube defects (i.e. spina bifida)

alcohol blocks reabsorption of monoglutamate in jejunum

Question 4

Hyperhomocysteinemia

Answer 4

deficiency of cystathionine synthase

Vitamin deficiencies

• Folate/ B12 (needed for homocystein N-methyltransferase; methionine synthase)
• Vitamin B6 (needed for cystathionine synthase and cysthionine lyase)

lens dislocation (after age 3)
osteoporosis
mental retardation
lipid deposits