Vitamins II

Vitamins II

1. Vitamin K

   • K1
     • plants
       • long, saturdated side chain
   • K2
     • fish
       • polyprenyl side chain
   • menadione
     • synthetic
       • water soluble
         • activated in liver
           • prenylation
   • enzymatic cofactor
     • carboxylation
       • glutamate residues
         • requires O2
     • substrates
       • prothrombiin
         • needs Ca, post-trans mod
           • active thrombin
         • anticoagulant drugs
           • dicumarol, warfarin
           • inhibit reductase
             • cannot convert oxidized K back to K
       • osteoalcin
         • binds Ca
         • regulates mineralization
   • nutrition
     • sources
       • leafy veggies, grains, liver
     • deficiency
       • increased coagulation time
       • impaired clotting, bruising
       • hemorrhagic disease of newborn
       • impaired fetal develoment of bony tissue
     • excess
       • infant
         • hemolytic anemia, jaundice

2. Vitamin A

   • forms
     • active form
       • all-trans-retinol
     • provitamin
       • B-carotene
         • antioxidant
           • cleave --> retinal
             • retinal reductasse --> retiol
             • only in intestinal mucosa
           • excess
             • not as teratogenic
           • inhibit lipid peroxidation
   • roles
     • visual cycle
       • 11-cis retinal
         • pigments
         • rhodopsin
           • photosensitive, 7 pass transmembrane
             • retinal rods
             • 11-cis-retinal bound to opsin
               • retinal is fat soluble
                 • to liver in chylomicrons
                   • stored in stellate cells
                     • retinyl esters
         • light converts to all-trans-retinal
           • signaling - cGMP phosphodiesterase, transducin
             • close Na channel, hyperpolarization
               • signals by optic nerve to brain
     • hormonal reg gene expression
       • all-trans retinoic acid
         • activates RAR and RXR
       • 9-cis retinoic acid
         • activates only RXR
           • heterdimerizes w/
             • receptors
               • vitt D
               • thyroid hormone
               • PPAR
             • transcription factors
       • RAR, RXR
         • bind response elements
           • promoter region
         • active
           • homo or heterodimers
       • > 500 genes
     • glycoprotein synthesis
   • deficiency
     • night-blindness
     • permanent ocular degeneration/blindness
       • lose vitreal fluid
         • extrude lens
       • lack of retinoic acid
     • lose hormonal activity
       • respiratory/urinary infection
   • excess
     • liver disease
     • teratogenicity
     • bone defects

3. Vtamin D

   • cholecalciferol
     • rxn of UV light w/ 7-dehydrocholesterol
   • active form
     • hydroxylations --> calcitriol
     • circulating form
       • 25-hydroxxycholecalciferol
   • roles
     • Ca absorption in gut
       • adequate serum [Ca] an [PO4-]
     • bone growth/remodeling
     • modulates
       • neuromuscular and immune function
         • reduce inflammation
       • gene expression
         • cell proliferation, differentiation, apoptosis
   • sources
     • sunshine, food, fortified foods
   • deficiency
     • rickets
     • osteomalacia
   • excess
     • hypercalcemia
       • metastatic calcifications
       • bone demineralization
       • renal stones

4. Vitamin E

   • vitamers
     • 8 compounds
     • tocopherols
       • saturated phytyl tail
     • tocotrienols
       • trienols
       • unsaturated phytyl tail
   • active form
     • a-tocopherol
       • phenolic ring most is effective
         • donates H+
           • terminates free radicals
   • sources
     • veggie oils, fatty tissues of animals
   • antioxidant
     • free radical scavenger
       • protects PUFA in membrane
     • terminates free radical lipid peroxidation
     • prevent heart disease?
       • limit oxidation of LDL-cholesterol
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   • deficiency
     • fragility/destruction
       • erythrocytes
     • nerve degeneration
       • hands/feet