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VIT METABOLISM
(10/10) (Vit Bs (B6 - Pyridoxine (PLP)
Group of 3…
VIT METABOLISM
(10/10)
Vitamins
- 1912 - Casimir Funk: B1 in rice bran "Vit" (vital amines)
- Organic compounds req'd as a nutrient in tiny amts
- Can't be synthesised in sufficient quantities, must be from diet
~ Vit D? - ; vit D yoself, from cho
- diff superheroes 2g
- consumed in smol amts
Diverse biological functions:
- Hm-like functions as regulators of mineral metabolism (vit D)
- Regulators of cell/T growth/differentiation (A)
- Antioxidants (E & C)
- Enz cofactors - tightly bound to enz as a part of prosthetic gr
- Coenzs
Coenz & Enz Cofactors :pencil2:
- diverse gr, funcs
~ coe: e- donor/acceptor, allow Rs to occur
~ enz cof: act in a structural mechanism
- eg incomplete enz A.site, req enz cof for R -
v specific
-
Deal w
Oxidative Stress
Reactive Oxygen species (ROS) cause damage
- Pros & sugars (glycation)
- DNA (mutations)
- Membranes (lipid peroxidation)
- O2 from mta -> free radicals be more e-
Vit Classification
Lipid-soluble - A, D, E, K
- hydrophobic compounds, absorbed efficiently w lipids
- Transport in blood in LPs / attached to specific binding pros
~ processed in same way as lipid metabolism
~ bound to stuff, need bile to be absorbed in GIT
- More likely to amass in body - x easily rid of
- & lead to toxicity = hypervitaminosis
- can go weeks, months w/o A
- stored heaps, so x affected if suddenly lac
Water-soluble - 8 Bs, C
- hydrophilic compounds dissolved easily in water
~ liver can get rid?
- X readily stored, excreted from body
- Consistent daily intake is important -
deficiency problems
- Many types synthesised by bacteria
- x ; vit Bs in cells, must be from diet
Vit Bs:
- 1 - Thiamin
- 2 - Riboflavin
- 3 - Niacin
- 5 - Pantothenic Acid
- 6 - Pyridoxine, Pyridoxamine
- 7 - Biotin
- 9 - Folic Acid
- 12 - Cobalamin
B1 - Thiamin
- Active coenz - thiamin pyrophosphate, TPP
~ catalyse oxidative decarboxylation of 𝛂-ketoacids
~ pyruvate DH in CHO metabolim
~ a-KG DH -> TCAc
- Role: CHO & AA metm, DNA/RNA/ntra synthesis
- Deficiency = problems w é, ntra production - problems w "roles"
- Beriberi: x enough ntras
~ CNS problems -> memory loss (amnesia), confusion (delirium), ataxia (gait coordination)
~ Peripheral neuropathy -> weak musc, wasting
~ Wernicke-Korsakoff syndrome -> alc-induced dementia (same symptoms)
- No toxicity symptoms - VERY water soluble
:pencil2: - x all cells in bod sensitive to lack of vits to others
- metabolic cells: liver, musc, br
- musc weak: x activated by motor system
- alc inhibit absorption of vit Bs
- Dementia: x enough é frm CNS
- no toxic: can consume many B1s
-
(pic) Vit -> Coenz
- a) Vits: Pro, carb, fat metabolism
- b) é 4 body functions
Vit Bs
B2 - Riboflavin
- Coenz flavin mononucleotide (FMN) &
flavin adenine dinucleotid (FAD)
- Both: act as prosthetic grs of many redox enzs
~ coenzs in proton transfer - FMNH2 & FADH2
~ Succinate DH - TCAc
~ Succinyl CoA-DH - b-oxi of FA
~ NADH-DH - mitochondrial respiratory chain
- Deficiency: rare - bc errwhere
~ Problems w proliferation in high cell turnover Ts
- inflamed lining of mouth, tongue
- dry, scaling skin - keratitis, dermatitis,
Fe-deficiency anaemia
- No toxicity
:pencil2: - FAD: e- carrier (FADH)
- high proliferative: use high é to turnover*
B3 - Niacin
- forms: nicotinic acid & nicotinamide
- NAD a NADP -> coenzs in CHO, aa, lipid metm (TCAc)
- Biosynth: liver can slowly synth B3 from Tryptophan (ess aa)
~ can synth lil amt in gut - x enough to keep alive
~ need also from diet
- Deficiency: affects T w high é requiremts / cell turnover
~ Pellagra: srs deficiency of B3
~ "the 4 D's": diarrhoea, dermatitis, dementia, death
~ v rare now -> alcoholics, strict vegetarians, v poor nutrition (corn: low Trp)
- No toxicity
B5 - Pantothenic Acid
- A-CoA: consists of pantoic acid & b-alanine
- Co-A ess for:
~ TCAc - ; ketoacids eg pyruvate
~ FA metm
~ Form Sterols (cho & 7-dehydrocholesterol)
~ ; Ach
- Deficiency: v rare in hs
~ "Pantothen" = "everywhere" Greek
~ General metabolic deficiencies
~ leads to paresthesia - pins & needles
~ disorders of synthesis of Ach - neurological symptoms
- No toxicity - even a 2000x the RDI
Vit Bs
B6 - Pyridoxine (PLP)
- Group of 3 related compounds
- Precursor of active coenz Pyridoxal Phosphate - PLP
~ coenz in AA synth & gluconeogenesis
- Ess 4:
~ RBC metm, Hb 🐝
~ & Ntra biosynth
- Deficiency: anywhere need lotsa procs, exchange of sugars
~ Anaemia
~ Neurological/CNS problems (ntras) - seizures, confusion, depression
~ Inflam GIT (stomatitis, glossitis) & skin (dermatitis)
- Toxicity - >200mg/day
B7 - Biotin
- Prosthetic gr of several ATP-dpdt Carboxylase enzs
(Pyruvate & A-CoA Carboxylase)
- Coenz 4 FA synth, gluconeogenesis, CHO & fat & pro metm
- Deficiency: rare - problems in high proliferative cells
~ Inflame GIT, sk
~ if consume raw eggs - contain avidin, binds Biotin
~ ;ed by gut bacteria
- No toxicity
B9 - Folic Acid
- Folic from "foliage" - in green leaves
- Ingested Folate (Pteroylgulatmic acid)
must be de-glutamated, then hydrated -> tetrahydrofolate (THF -> active metabolite)
- THF: coenz of many Trasnferases
~ Ess in pu, py (DNA, RNA) synth
- Deficiency: v rare - high turnover / RNA synth
~ RBCs -> anaemia (macrocytic = immature RBCs)
~ Nervous sys -> depression, confusion, delirium
~ in pregnancy: can ; birth defects
- eg neural tube defects - spina bifida
x enough proliferation -> CNS problems
:pencil2: delirium: restless, illusions, incoherence
B12 - Cobalamin
- Catalyse Rs of 2 enzs:
~ Methionine Synthase - DNA synth
~ Methylmalonyl-CoA Mutase
(MMCoA -> Succinyl CoA): é metm
- Ess 4 é metm, pu + py synthesis
~ same as B9
~ RBC maturation, cell growth, NS maturation
- Deficiency: high turnover / RNA synth
~ RBCs -> (same as B9)
~ NS -> fatigue, amnesia, depression, delirium
~ Common: >40% vegetarians, 80% vegans
~ Rec-mediated uptake w intrinsic factor
:pencil2: v similar to B9
- D, RNA, ntras synth
- Deficiency common bc absoroption in gut is complex,
~ lots problems
~ too much stomach acid
- Cells that ; stomach acid 4 absorption of B12
Outcomes:
- Know fat & water soluble vits & und how this influences their metabolism
- Describe metabolic pathways of specific vits (highlighted)
- Know funcs of specific vits
- Outline biological effects over under/over supply of different vits