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Metabolism > Metal metabolism > Flashcards

Metal metabolism Flashcards

1
Q

loop of geomicrobiology

A
  • geosphere minerals undergo bacterial leaching of metal ions
    = biosphere proteins
  • biosphere proteins undergo bacterial deposition of metal ions
    = geosphere minerals
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2
Q

what metal is debatably essential

A

chromium

  • difficult to demonstrate deficiencies because of ethics.
  • haven’t found a reason that it is essential
  • however it is present, suggesting that it might be
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3
Q

essential metals of focus

A

Mn
Fe
Cu
Zn

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4
Q

how much Zn is present in a 70kg human body

A

2-3g

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5
Q

how much Cu is present in a 70kg human body

A

100mg

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6
Q

how much Fe is present in a 70kg human body

A

3-5g

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7
Q

how much Mn is present in a 70kg human body

A

12-20mg

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8
Q

functions of metals in proteins

A
  • catalytics; 50% enzymes require metals
  • structural; tertiary, quaternary, quinary
  • regulatory
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9
Q

what is quinary structure of proteins

A

different types of proteins coming together

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10
Q

What are the different ligands of metal in proteins

A

N: Hist
O: Glu, Asp
S: Cys

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11
Q

what does N ligand stand for

A

Hist

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12
Q

What does O ligand stand for

A

Glu, Asp

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13
Q

What does S ligand stand for

A

Cys

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14
Q

method of identifying if protein has metal-binding sites

A

looking at the spacing of the amino acids

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15
Q

example of a kown Zn proteinase

A

Thermolysin found in bacteria

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16
Q

example of a putative Zn proteinase

A

LTA4 hydrolase found in human)

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17
Q

mining sequence database

A
  • structural genomics. search for 3D structure of metalloprotein (protein database PDB)
  • determine liganvd signatures
  • search for homology in sequence database
  • find putative metalloprotein (curator)
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18
Q

what is the indirect method whih predicts the sizes of human metalloproteins

A

mining sequence database

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19
Q

what % of entire proteome is non heme Fe

A

1.1%

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20
Q

what % of entire proteome is Cu

A

0.3%

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21
Q

what % of entire proteome is Zn

A

10%

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22
Q

what % of entire protoeme is Mn

A

?

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23
Q

how do ligand interactions differ between metals

A

as you move down the periodic table, ionic radius increases and coordination numbr increases
= weaker ligand interactions

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24
Q

what is the function of Na+ and K+

A

they are minerals needed for nerve conductions. Need proteins to maintain electrochemical gradietnq

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25
Q

sodium requirements

A

2.3g/day

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26
Q

potassium requirements

A

4.7g/day

27
Q

sodium and potassium inside cells

A

Na+: 12mM

K+: 140mM

28
Q

sodium and potassium outside cells

A

Na+: 140mM

K+: 5mM

29
Q

function of Mg2+

A
  • cofactor
  • enzyme complexes
    e. g ATP is nearly always a magnesium complex
30
Q

what is ATP nearly always a complex of

A

Magnesium complex

31
Q

Essentail trace metals

A 
Mn
Fe
Co
Cu
Zn
Mo
32
Q

when is Ni essential

A

good bacteria in the gut need Ni

33
Q

what is Mo

A

molybdenum

  • only 4 enzymes in humans with Mo
  • pterin cofactor binds Mo
34
Q

Use of Co

A
  • only 2 enzymes in humans (methylmalonyl-CoA, methionine synthase)
  • Is the centre of vitamin B12 structure
  • vitamin B12 = cobalamin
35
Q

Uses of Mn

A
  • Mn deficiency is uncommon
  • too much Mn causes Manganism = Parkinson’s
  • total number of Mn enzymes is unknown (mitochondiral superoxide, dismutase, arginase, pyruvate decarboxylase)
36
Q

Uses of Ni

A

only 9 enzymes, but none have been identified in the human body.
Good bacteria found in the gut need Ni

37
Q

Cu uses

A
  • deficiency causes Menkes disease = fatal
  • overload causes Wilson’s disease = treatable with chelating agen of Zn supplementation
  • dozens of human Cu enzymes (superoxide dismutuase, cytochrome C oxidase)
  • mostly found as Cu+ because intracellular environment is highly reducing
  • metallochaperones prevent free radicals being formed
38
Q

cuprous

A

Cu+

39
Q

cupric

A

Cu2+

40
Q

what prevent formation of free radicals

A

metallochaperones

41
Q

what controls mammalian intracellular copper homeostasis

A
  • tightly controlled by transporters and metallochaperons
42
Q

uses of Fe

A
  • redox active which gives most of its functions:
  • 250 non-heme proteins
  • oxgen transport and activation
  • many proteins
  • overload and deficiency can occur
43
Q

ferrous

A

Fe2+ = active iron

44
Q

ferric

A

Fe3+ = storage iron

45
Q

what is the state of active iron

A

Fe2+, ferrous

46
Q

what is the state of storage iron

A

Fe3+, ferric

47
Q

how is Fe2+ found

A
  • in Fe/S clusters
  • bound to heme
  • non-heme Fe; mononuclear and dinuclear
48
Q

examples of heme iron proteins

A
  • hemoglobin
  • myoglobin
  • cytochomes
  • peroxidase
  • catalase
  • heme-binding proteins (sensors and transporters)
49
Q

when does iron redox recycling occur

A

aerobic iron metabolism

50
Q

process of iron redox recycling

A
  • iron is outside of enterocyte in intestine as Fe3+
  • Dcytb on membrane reduces iron to Fe2+
  • Fe2+ transported across membrane via DMT1
  • most of iron stored in cell as Ferritin
  • remaining exported as Fe2+ via Fpn
  • Fe2+ is oxidised again outside cell by Hp
  • Fe3+ binds to Tf for transportation in blood
51
Q

Tf

A

transferrin = transport protein

52
Q

Ft

A

ferritin = storage protein

53
Q

DMT1

A

divalent metal transporter 1

54
Q

Dcyt b

A

duodenal cytochrome b

55
Q

Hp

A

hephaestin

56
Q

Fpn

A

ferroportin

57
Q

what is ferritin

A
  • complex proteon with an iron mineral core, where iron is storoed as on oxide
  • iron oxidase acitivity
  • once iron has been oxidised, it migrates to the core for storage, hence iron core
58
Q

what is transferrin

A
  • uses Fe3+
  • binds two Fe3+ from intestine cell and transport to blood where needed
  • has two biding sites
  • transferrin uptake by cells is by receptor mediated endocytosis
59
Q

transferrin receptor

A
  • two irons bind to receptor
  • pit forms an endosome to enter cell
  • endosome is acidified to release iron into cell
  • protein recyled to surface, both Tf and Tf receptor
60
Q

what happens to iron during cyctochrome P450 reaction cycle

A

goes to very high oxidation state: Fe5+

61
Q

inborn errors of Cu metabolism

A

Deficiency: copper deficiency, Menkes disease
Overload: copper toxicity, Wilson’s disease

62
Q

inborn erros of Fe metabolism

A

deficiency: iron deficiency
overload: iron toxicty, primary iron overload disorders: hemchromatosis (HFE1-4), aceruloplasminemia, atransferrinemia, hemosiderosis

63
Q

inborn errors of Zn metabolism

A

deficiency: acrodermatitis enteropathica
overload: zinc ‘toxicity’

64
Q

Which one of the following elements is believed to be non-essential

A

aluminium

Metabolism (11 decks)

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