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Pharmacy year 2 > An introduction to inorganic chemistry 1+2 > Flashcards

An introduction to inorganic chemistry 1+2 Flashcards

1
Q

what are the most abundant elements employed in mammalian biochemistry?

A

C,N,O,H,S,P but augmented by a range of other elements many of which are metals , I, Se, Cl, Na, K, Ca, Mg, Co, Cu, Ni, Zn,Fe, Mo, V

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2
Q

What are many of the metals associated with

A

a protein - 1/3 of proteins are metalloproteis

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3
Q

what does each period correspond to?

A

the completion of the s and p subshells

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4
Q

what happens to atomic radii down a group and across a period (left to right)

A

increases down a group and from left to right across a period

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5
Q

what happens to ionisation energy across the 1st period?

A

across the 1st period ionisation energy increases left to right

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6
Q

what is electron affinity

A

is is a measure of how strongly an atom or molecule can attract an extra
electron

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7
Q

what is electronegativity?

A

the ability of an atom within a compound to attract electrons towards itself

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8
Q

what is polarisability?

A

the essentially underpins the idea of Hard and soft Lewis acids and bases’ it is the ease with which an atom or ion can be distorted by an electric field.

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9
Q

what are the hardest atoms and ions?

A

the hardest atoms and ions are those with low ionisation energy and low electron affinity

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10
Q

what are the softest atoms and ions

A

those with low ionisation energy and low electron affinity

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11
Q

soft acids and bases are

A

more polarisable and form bonds with more covalent character

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12
Q

what are the biological roles performed by metals

A

structural
catalytic
redox
other

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13
Q

hard acids and bases are

A

less polarisable and form bonds with more ionic character

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14
Q

what are the factors that influence the role of the metal

A

valency, ionic radius, polarisability
hydration energy (ease with which water molecules can be removed from the metal ion).
radius of the hydrated ion.

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15
Q

Lewis acids and bases

A

theory introduced by the American chemist G.N Lewis

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16
Q

what does the theory state

A

that hard acids prefer hard bases while soft acids prefer soft bases

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17
Q

what did this theory allow?

A

metal ligand interactions to be described- ligand is the Lewis base and metal the Lewis acid

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17
Q

define a Lewis acid

A

substance accepts an electron pair

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17
Q

define Lewis base

A

substance that donates an electron pair

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18
Q

properties of hard acids

A

high charge density
small ionic radius
not easily polarisable
Na+, K+, Mg2+, Ca2+, Fe3+, Co3+

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19
Q

Properties of hard bases

A

not easily polarised
high electronegativity
vacant, high energy orbitals
hard to oxidise
H2O,-OH, CO2-, CO22- , NO-3, PO3- 4, ROH, RO-, R2O, NH3, RNH2, CL-

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19
Q

Acid intermediate

A

Fe2+, Co2+,Ni2+, Cu2+, Zn2+

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20
Q

base intermediate

A

NO-2, Br-, Imidazole

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20
Q

soft acid

A

low charge density
large ionic radius
more polarisable Cu+

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21
Q

soft base

A

high polarisability
low electronegativity
low energy vacant orbitals easily oxidised RSH, RS-, CN-, CO

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22
Q

shape of a molecule can be defined by ?

A

bonds electron pairs within it so it is possible to predict the geometry of coordination compounds.

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23
Q

linear

A

2 numbers of pairs
alkyne (sp)

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24
Q

Equilateral triangle

A

alkene sp2
3 numbers of pairs

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25
Q

tetrahedron

A

alkane sp3
3 numbers of pairs

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26
Q

trigonal bi-pyramidal square pyramid (less stable)

A

AsF5 sp3d
5 numbers of pairs

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27
Q

octahedron

A

6 numbers of pairs
SF6 sp3d

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28
Q

what do different metals prefer?

A

different coordination numbers ( different numbers of ligands bonded to the metal)- hence, different geometries

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29
Q

what are the most common coordination geometries found in biological systems?

A

4 and 6 and 5

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30
Q

are many metals fixed to only one geometry

A

are not fixed to only one coordination geometry

31
Q

what are the common geometries

A

tetrahedral
square planar
octahedral

32
Q

what can ligands be

A

monodentate or polydentate

33
Q

define polydentate

A

more than one point of attachment to the metal

34
Q

define monodentate

A

only one point of attachment to the metal

35
Q

what types of ligands feature in biology

A

both types of ligand feature in biology, but the polydentate ligands are critical features of a range of important biological molecules

36
Q

examples of ligands

A

copper glycine
ciprofloxacin
EDTA

37
Q

what are macrocyclic ligands

A

in biological sense, these are a special case of polydentate ligands
a macrocyclic molecule is a cyclic molecule with at least 9 atoms containing at least 3 donor atoms Lewis base typically N, O, S or P

38
Q

are macrocyclic complexes generally thermodynamically and kinetically more stable than non-cyclic ligands

A

yes they are

39
Q

why are they more stable

A

essentially its the chelate effect
simply stated, complexes with polydentate ligands will be more stable than complexes with similar mono dentate ligands, favourable entropic factor accompanying the release of nonchelating ligands from the metal ion.
it is generally the case that stability increases with the number of donor atoms in the ring

40
Q

biological examples

A

the porphyrin unit
a simplified haem unit

40
Q

what’s the clinical significance of chelation?

A

metal ions are widely distributed throughout the body
a range of drugs can behave as chelating ligands,

chelation changes both the physical and chemical characteristics of both components ie the metal and the ligand

41
Q

what is the clinical significance of chelation

A

the tetracyclines
broad spectrum antibiotics - value has decreased over recent years due to resistence
treatment of choice for certain infections
-chlamydia
rickettsia
brucella
Lyme disease
also respiratory and genital mycoplasma infections
tigecycline reserved for treatment of complicated skin and soft tissue infections and complicated abdominal infections caused by multiple antibacterial resistant organisms

41
Q

what is the tetracyclines mode of action?

A

bacteriostatic agents
tagets 305 subunit
selective -very little binding to mammalian ribosomes
block binding of aminoacyl tRNA in the A-site
involving Mg2+ ions

42
Q

examples of tetracyclines

A

doxycycline , monocycline
oxytetracycline, tetracycline demeclocycline

42
Q

are most metal chelates insoluble?

A

yes most of the metal chelates are insoluble

43
Q

what is absorption of tetracyclines affected by?

A

extent of chelation with metal ions

44
Q

tetracyclines form what?

A

form chelates with a range of metal ions Ca2+, Mg2+, Al3+, Fe2+, Zn2+

45
Q

with M3+ what is produced?

A

they form 3:1 drug-metal chelates

46
Q

with M2+ what is produced ?

A

2:1 drug metal chelates

47
Q

iron (II)

A

ferrous sulfate , ferrous fumarate and ferrous gluconate

48
Q

calcium (II)

A

calcium carbonate

49
Q

What do aluminium and or magnesium hydroxide based antacids do?

A

reduce the absorption of the tetracyclines

50
Q

who cannot have tetracyclines

A

not recommended for children under the age of 12 due to discolouration of the teeth (ranges from greyish to yellow) the effect is dose dependent and permanent

tetracyclines are also not recommended for pregnant or breast feeding women - this is connected to the effect on skeletal growth

51
Q

what isa key aspect of metal ions ?

A

in their ability to stabilise conjugate bases

52
Q

what does this do to the pka of the parent acid

A

it is frequently lowered

53
Q

what is calmodulin?

A

proteins involved in the meditation of the Ca2+ signal in large number of pathways sometimes found as part of enzyme complexes phosphorylase kinase

54
Q

describe calmodulin?

A

small acidic protein
dumbbell shaped protein that binds 4x Ca2+ ions

the major donor groups from the protein that bind to the Ca2+ ions are carbonyl and carboxylate groups binding is complex involving a specific set of Lewis bases so as not to stabilise cross-links within the protein.

55
Q

key properties of Ca2+ ions

A

binding- it is selective but differs from Mg2+ ion in a number of key ways can interact with neutral oxygen donors carbonyls and ethers

it can bind to a number of centres at once - irregular coordination geometry

ligands- Ca2+ ions readily exchange water with other ligands - with a complex, the ligands on the ion are fluctional

55
Q

Ca2+ and its biological roles

A

metabolism- numerous enzymes inside cells

cell division- S-100 proteins, immune system

cell death (apoptosis)- internal proteases

binding to membranes- C-2 domains of enzymes

Phosphorylation -activation of kinases involved in fertilisation of the egg

hormone transmitter release- homeostasis

blood clotting- involved in both the intrinsic and extrinsic pathways

56
Q

Mg2+ ions and DNA/RNA

A

although the role of Mg2+ ions in a number of RNA/DNA units is significant , it is perhaps its role in tRNA and ribosomes that are amongst the most important

57
Q

tRNAs contain regions known as?

A

half crucifixs
Mg2+ ions are key to holding this shape

58
Q

what do ribozymes require Mg2+ ions to do ?

A

catalyse their splicing reactions

59
Q

what is RNA

A

RNA ribonucleic acid
multiple functions
chemically, RNA is relatively simple
RNA forms a range of stable structures
RNA can perform catalytic functions (ribozymes)

60
Q

tRNA requirement

A

at least one strong site and many weaker sites
fold stabilisation
half crucifix structures

60
Q

what Is DNA?

A

DNA- deoxyribonucleic acid
serves as the information store
chemically DNA is a relatively simple molecule

DNA can detect its own replication
The DNA double helix is remarkably stable

61
Q

rRNA

A

Stabilisation of fold and association with 30S 50S and 70S subunits

62
Q

mRNA

A

attachment to ribosomes

63
Q

ribozymes

A

Mg2+ acts to bind the RNA enzyme to the RNA enzyme to the RNA substrate

64
Q

DNA

A

Crucifix structures

65
Q

DNA/ RNA

A

polymerase

66
Q

magnesium is required as

A

requires of various polynucleotides

67
Q

kinases

A

the reversible phosphorylation of protein , resulting in a conformational change in that protein provides a useful control mechanism that allows for the activity of an enzyme to be modulated

68
Q

what’s under this control mechanism

A

many proteins are under this controlled mechanism

69
Q

what do protein kinases do?

A

add the phosphate group

69
Q

phosphorylation takes place in which 3 amino acids

A

serine threonine or tyrosine
the phosphate is supplied as the Mg-ATP complex

70
Q

phosphateses

A

remove the phosphate group

71
Q

where is the ATP bound

A

The ATP is bound into the protein via the adenine leaving the phosphate chain exposed , or weakly bound

72
Q

what does an anion centre on the protein do?

A

An anion centre on the protein then helps to move the triphosphate into position so it can transfer the terminal phosphate group group to the requisite amino acid

73
Q

is phosphorylation restricted to a single site?

A

no it is not restricted to a single site on the protein and the protein may be phosphorylated by more than one kinase this allows convergence of cell signalling pathways

Pharmacy year 2 (5 decks)

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