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Cardiovascular and Haematology (PHAR1017 ) year 1 > Protein function and intro to enzymes > Flashcards

Protein function and intro to enzymes Flashcards

1
Q

name of protein complexes?

A

monomer
homodimer
heterodimer
tetramer
trimer
multimer

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2
Q

what are haemoglobon and myoglobin for?

A

transport oxygen
store protein

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3
Q

structure of haemoglobin?

A

‘4 polypeptide chains folded to form 8 alpha helices’
haem prosthetic group

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4
Q

structure of myoglobin?

A

‘single polypeptide chain folded to form 8 alpha helices’
haem prosthetic group

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5
Q

what binding is oxygen binding to haemoglobin?

A

cooperative

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6
Q

what is allostery?

A

w’hen oxygen binding causes a change from tense (T) to relaxed (R) state and increases ease of oxygen binding to other subunits’

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7
Q

who’s affinity for oxygen is higher?

A

‘myoglobin has a higher affinity for oxygen than haemoglobin’

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8
Q

where does haemoglobin bind to oxygen and where does it release it?

A

binds in lungs and releases in capillaries and myoglobin in the muscles for storage

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9
Q

what is the conformation change in haemoglobin?

A

when oxygen binds it pulls Fe2+ into haem plane and His ligand and F helix effecting its 3D structure

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10
Q

what happens if oxygen isn’t bound?

A

‘Fe2+ is out of haem plane’

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11
Q

what is the Bohr effect?

A

decrease in affinity of haemoglobin for oxygen
pH of blood decreases becuase carbon dioxide converted into carbonic acid carbonic acid produces protons that react with amino acids
causing oxygen to be released easier at cells

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12
Q

what is the transition state?

A

a form between substrate and product that is unstable
has the highest free energy

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13
Q

what does an enzyme do?

A

‘stabilizes transition state and lowers DG‡
increases the rate at which the reaction occurs’

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14
Q

what is the reaction of saturation kinetics?

A

slide 18
protein functions and enzymes

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15
Q

what is Km?

A

the substrate concentration where V=Vmax/2

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16
Q

what is the Michaelis-Menten equation?

A

slide 19
protein functions and enzymes

17
Q

what does the Michaelis-Menten equation measure?

A

the affinity of enzyme for substrate

18
Q

what curve does Vo against S give?

A

hyperbolic curve

19
Q

what is the Michaelis constant Km?

A

‘The [S] required to produce a reaction rate equal to half the Vmax’

20
Q

what is the graph of Michaelis – Menten Enzyme Kinetics?

A

slide 18
protein functions and enzymes

21
Q

relationship between Km and substrate?

A

the lower the Km the higher its affinity for substrate

22
Q

relationship between Vmax and enzyme concentration?

A

directly proportional

23
Q

how is in the form of a straight line generated from Michaelis-Menten?

A

The reciprocal of both sides of the Michaelis-Menten equation

23
Q

what is used to linearize Michaelis-Menten?

A

Lineweaver-Burk plots

24
Q

what is the equation for the reciprocal of Michaelis-Menten equation?

A

slide 21
proteins and enzymes function

25
Q

what does induced model fit require for substrate to bind?

A

conformation change of the enzyme

26
Q

what are the catalytic mechanisms of enzymes involved in lowering the activation energy?

A

Acid –Base (proton donation/abstraction)
Temporary covalent bond formation
Redox effects
Electrostatic effects
Orientation/proximity effects and straining effects

27
Q

what are cofactors?

A

non-protein molecules needed for a reaction to happen

28
Q

what are coenzymes?

A

‘cofactors that bind loosely and chemically altered by the enzyme’
they are recycled to be used again in the same reactions

29
Q

what are enzymes with a cofactor called?

A

holoenzyme

30
Q

what are enzymes without a cofactor called?

A

apoenzyme

31
Q

how are enzyme activities regulated?

A

enzyme inhibition
covalent modification
allosteric regulation
substrate availability
product accumulation
genetic control

32
Q

what is competitive inhibition?

A

molecule competes with substrate for binding site

33
Q

what is covalent modification?

A

‘a covalent modification of amino acid residue’

34
Q

examples of covalent modification?

A

phosphorylation, methylation

35
Q

what is allosteric regulation?

A

‘non-covalent binding of a molecule and doesn’t compete with substrate binding
binds away from active site but causes conformational change
this can either increase or decrease enzyme activity’

36
Q

why are enzymes important for pharmaceutical sciences?

A

change in enzyme activity causes change in product concentration
they effect substrate molecules

Cardiovascular and Haematology (PHAR1017 ) year 1 (14 decks)

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