Amino Acid part1 Flashcards by Thejas B | Brainscape

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

Q

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

A

Arginine, Lysine and Histidine

Q

Which are the polar amino acids?

A

Asparagine
Glutamine
Serine
Threonine
Tyrosine

Q

Difference between aspartic acid and glutamic acid?

A

Glutamic Acid has an extra methyl

Q

Glutamic Acid and Aspartic Acid are polar or nonpolar?

A

Very polar

Q

Glutamic acid and aspartic acid often act as what?

A

Chelators of metal ions

Q

How do chelates work?

A

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

Q

Basic side chains have what charge?

A

Positive

Q

How many methyl groups in total in

a) Asp
b) Glu

A

a) 1

b) 2

Q

How many methyl groups in

a) Lysine
b) Arginine
c) Histidine

A

a) 4

b) 3

Q

Arginine has what group?

A

Guanidino, so 3 separate NH groups

Q

Guanidino group has what feature?

A

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

Q

Histidine has what group

A

Imidazole ring

Q

The imidazole ring has what properties?

A

Nucleophile (deprotonated form) or electrophile

Q

Histidine is highly used where?

A

In enzyme active sites

Q

Asn and Gln have what side chain?

A

Amide

Uncharged polar side chain

Q

The amide side chains have what character?

A

Partial double bond character, group planar like peptide bond

Q

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

A

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

Q

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

A

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

Q

Trp has the following properties

a) what does it absorb?
b) rich in what
c) donor for

A

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

Q

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

A

Trp

Q

Aliphatic side chains are what?

A

Hydrophobic

Q

Valine has how many methyl groups but they are what?

A

2 methyl but they are beta branched

Q

Comparison between Val, Leu and Isoleucine

A

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

Q

Isoleucine has what in comparison to leucine?

A

An extra methyl so an extra chiral centre