Amino Acid part1 Flashcards by Thejas B

Q

Alpha carbon has what type of symmetry?

A

Asymmetry

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Q

asymmetry allows for what type of isomer?

A

stereo

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Q

What are the 2 types of stereo isomers?

A

L and D

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Q

Proteins consist of mainly what stereo isomer

A

L

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Q

Simplest way to remember the spatial orientation of groups about the alpha carbon of L amino acids is

A

CORN

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Q

L amino acids all have the same what?

A

Stereochemistry, the side chain R group is in the same position

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Q

L amino acids dont all do what the same?

A

Dont all rotate plan polarised light the same way

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Q

D and L amino acids can be made from

A

Their glyceraldehyde precursor

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Q

Side chain angles can be described by what and what are they called

A

By dihedral/torsion angles, chi angles. X

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Q

pKa is what?

A

Is pH when HA=A-, 50% ionisation

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Q

Which amino acids have ionisable C terminal side chains? And what are their pKas roughly

A

Asp
Glu
His
pKas are less than 7

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Q

Which amino acids have ionisable N terminal side chains? and what are their pKas

A

Cys
Tyr
Lys
Arg
pKas are more than 8

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Q

One letter coding and three letter coding for

Glutamic Acid

A

Glu, E

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Q

One letter coding and three letter coding for

Aspartic Acid

A

Asp, D

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Q

One letter coding and three letter coding for

Arginine

A

Arg, R

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Q

One letter coding and three letter coding for

Lysine

A

Lys, K

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Q

One letter coding and three letter coding for

Histidine

A

His, H

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Q

One letter coding and three letter coding for

Asparagine

A

Asn, N

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Q

One letter coding and three letter coding for

Glutamine

A

Gln, Q

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Q

One letter coding and three letter coding for

Threonine

A

Thr, T

Q

One letter coding and three letter coding for

Tyrosine

A

Tyr, Y

Q

One letter coding and three letter coding for

Proline

A

Pro, P

Q

One letter coding and three letter coding for

Tryptophan

A

Trp, W

Q

Which amino acids have a negative side chain? So which ones produce COO-

A

Aspartic Acid and Glutamic Acid. Lose their H, proton donor

Which amino acids have a positive side chain? So which ones produce NH3+

Arginine, Lysine and Histidine

Which are the polar amino acids?

``` Asparagine Glutamine Serine Threonine Tyrosine ```

Difference between aspartic acid and glutamic acid?

Glutamic Acid has an extra methyl

Glutamic Acid and Aspartic Acid are polar or nonpolar?

Very polar

Glutamic acid and aspartic acid often act as what?

Chelators of metal ions

How do chelates work?

The oxygens form a coordinate complex with a metal. | Eg Ca2+ in the middle, surrounded by 6 oxygens from other molecule such as from Asp or Glu

Basic side chains have what charge?

Positive

How many methyl groups in total in a) Asp b) Glu

a) 1 | b) 2

How many methyl groups in a) Lysine b) Arginine c) Histidine

a) 4 | b) 3

Arginine has what group?

Guanidino, so 3 separate NH groups

Guanidino group has what feature?

Is planar and stabilised by resonance. The charge is delocalised over the whole group

Histidine has what group

Imidazole ring

The imidazole ring has what properties?

Nucleophile (deprotonated form) or electrophile

Histidine is highly used where?

In enzyme active sites

Asn and Gln have what side chain?

Amide | Uncharged polar side chain

The amide side chains have what character?

Partial double bond character, group planar like peptide bond

Difference between Serine and Threonine and what do they have in common?

Both have OH, so hydroxyls Threonine has a methyl group but after the carbon whereas no methyl groups for serine. So threonine has extra chiral centre

Phe, Tyr and Trp have what in common and what are their differences?

``` All aromatic (nonpolar rings) Tyr has OH, somewhat polar and can hydrogen bond. Trp has indole ring ```

Trp has the following properties a) what does it absorb? b) rich in what c) donor for

a) absorbs UV + fluorescent b) Electron rich so negative charge transfer c) Indole NH H bond donor

Phe, Tyr and Trp can absorb wavelengths but which absorbs the most?

Trp

Aliphatic side chains are what?

Hydrophobic

Valine has how many methyl groups but they are what?

2 methyl but they are beta branched

Comparison between Val, Leu and Isoleucine

Leu is a longer version of Val with an extra methyl pushing the branching to the gamma section

Isoleucine has what in comparison to leucine?

An extra methyl so an extra chiral centre