Amino Acids and Proteins Flashcards

1
Q

What are proteins?

A

Linear amino acid polymers of specific 3D structures

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2
Q

What does each protein have?

A

One conformation, a specific 3D structure

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3
Q

What shape can proteins take?

A

Fibrous or globular

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4
Q

What are fibrous proteins?

A
  • Mechanical support

- E.g. alpha-keratin

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5
Q

What are globular proteins?

A
  • Water soluble

- E.g. enzymes and receptors

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6
Q

What is the hydrophobic effect on globular proteins?

A
  • Forms a hydrophobic core
  • Surrounding the hydrophobic core are the hydrophilic side chains which can form hydrogen bonds
  • Forms a compressed globular protein
  • Enegetically favoured
  • Small amount of space
  • Large surface area
  • Shape of globular proteins is an adaption to the aqueous environment
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7
Q

What are amino acids made of?

A
  • Carboxyl group
  • Amino group
  • R group
  • Hydrogen
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8
Q

How do amino acids combine?

A
  • Peptide bond
  • Condensation reaction
  • Bond between carboxyl group of one amino acid and amino group of another amino acid
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9
Q

What are amino acids at physiological pH?

A
  • Charged amino group

- Charged carboxyl group

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10
Q

Non polar amino acids

A

Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, Phenylalanine

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11
Q

Aliphatic amino acids

A

Glycine, Alanine, Proline, Valine, Leucine, Isoleucine

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12
Q

Little amino acid

A

Glycine

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13
Q

Most abundant amino acid

A

Glycine

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14
Q

Branched chain amino acids

A

Valine, Leucine, Isoleucine

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15
Q

Aromatic amino acids

A

Phenylalanine, Tyrosine, Tryptophan

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16
Q

Polar amino acids

A

Tyrosine, Tryptophan, Asparagine, Glutamine, Serine, Threonine

17
Q

Uncharged amino acids

A

Asparagine, Glutamine, Serine, Threonine

18
Q

Sulpher containing amino acids

A

Methionine, Cysteine

19
Q

Charged amino acids

A

Aspartate, Glutamate, Arginine, Lysine, Histidine

20
Q

Negative )acidic) amino acids

A

Aspartate, Glutamate

21
Q

Positive (basic) amino acids

A

Arginine, Lysine, Histidine

22
Q

Primary protein structure

A
  • Linear sequence of amino acids
  • Loss of charge
  • Partial double bond properties
  • Side chains determine properties
  • N terminus to C terminus
23
Q

Secondary protein structure

A
  • Regions of regularly repeating conformations of the peptide stabilised by hydrogen bonds between the peptide groups
  • Local repeated folding of a polypeptide
  • Stabilised by H bonds
  • Alpha helix and beta pleated
  • Right handed alpha helix, each carboxyl group is h bonded to the amide hydrogen 4 places ahead
24
Q

Tertiary protein structure

A
  • 3D shape of the folded chain
  • Arrangement of all amino acids including R groups and any prosthetic groups
  • Monomeric
25
Q

Quaternary structure

A
  • Arrangement of two or more polypeptide subunits in an oligomeric protein
26
Q

Myoglobin

A
  • Monomeric
  • Globular protein
  • Right handed alpha helix
  • Haem group
27
Q

Haemoglobin

A
  • Allosteric protein
  • Only alpha helix
  • 2 b globin and 2 a globin
  • Tetramer organised as 2 dimers
  • 4 haem groups
  • 1 O2 group per haem group
  • Quaternary structure
28
Q

Collagen

A
  • Major protein in connective tissue
  • Extracellular protein
  • Diverse forms
  • Triple stranded tropocollagen molecule
  • Three left handed helical chains coiled around each other
29
Q

Diagnostic use of enzymes

A
  • Non functional plasma enzymes are cellular enzymes released into the blood after tissue damage
  • Isozymes are tissue specific physically distinct forms of a given enzyme
  • % of isozyme present can indicate organ damage
30
Q

Denaturation

A
  • Causes unfolding of native conformation
  • Extremes of pH
  • Extremes of temperature
  • Organic solvents
  • Leads to loss of secondary/tertiary structure (bond disruption)
  • Most proteins cannot refold after removal of denaturant
31
Q

Altered folding

A

Leads to prions and amyloid proteins