Amino Acids Flashcards by Precious Purple Puppy

Q

What are the 4 distinct structures of an Amino Acid?

A

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Q

What are the rules for a fisher projection?

A

Horizontal lines = groups coming towards you.
Vertical Lines = groups going away from you.
Intersection =Alpha Carbon(Chiral carbon)

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Q

When placed in water, what happens to amino acids?

A

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Q

What are the 7 amino acids with an aliphatic, nonpolar side chain.

A

Aliphatic= Carbons that form linear/branched structure NO rings.

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Q

What is this amino Acid? What type of molecule is it?

A

P (Pro) Proline.
Aliphatic (Ring forms with amino group NOT itself)
Nonpolar side chain
Unique: its side chain, makes a ring by bonding with its main chain nitrogen.

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Q

What is this amino Acid? What type of molecule is it?

A

G (Gly) Glycince.
Aliphatic
Nonpolar side chain.
Unique: glycine has no side chain. It is achiral.

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Q

What is this amino Acid? What type of molecule is it?

A

I (Ile) Isoleucine
Aliphatic
Nonpolar side chain
Unique: is one of two amino acids with a chiral chain.

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Q

What is this amino Acid? What type of molecule is it?

A

A (Ala) Alanine
Aliphatic
Nonpolar side chain.

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Q

What is this amino Acid? What type of molecule is it?

A

V (Val) Valine
Aliphatic
Nonpolar side chain

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Q

What is this amino Acid? What type of molecule is it?

A

L (Leu) Leucine
Aliphatic
Nonpolar side chain

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Q

What is this amino Acid? What type of molecule is it?

A

M (Met) Methionine
Aliphatic
Nonpolar side chain

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Q

What are the 5 amino acids with an uncharged, polar side chain?

A

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Q

What is this amino Acid? What type of molecule is it?

A

S (Ser) Serine
Uncharged
Polar side chain

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Q

What is this amino Acid? What type of molecule is it?

A

T (Thr) Threonine
Uncharged
Polar side chain
Unique: one of the two amino acids that have a side chain, which is chiral.

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Q

What is this amino Acid? What type of molecule is it?

A

C (Cys) Cystine
Uncharged
Polar side chain
Unique: 1. Can form Disulfide bonds, 2. S is good nucleophile. 3. Good in coordinating metals 4.
pK of the SH is ~8.3

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Q

What is this amino Acid? What type of molecule is it?

A

N (Asn) Asparagine
Uncharged
Polar side chain

Q

What is this amino Acid? What type of molecule is it?

A

Q (Gln) Glutamine
Uncharged
Polar side chain

Q

What are the 3 amino acids with positively charged side chains?

A

Q

What is this amino Acid? What type of molecule is it? What’s the pK?

A

K (Lys) Lysine
Positive charged side chain
pK=10

Q

What is this amino Acid? What type of molecule is it? What’s the pK?

A

R (Arg) Arginine
Positively charged side chain
pK=12.5

Q

What is this amino Acid? What type of molecule is it? What’s the pK?

A

H (His) Histidine
Positively charged side chain (Generally neutral but about 10% is positive generally)
pK= 6
Unique: 1. The PK being six means that at a neutral pH the ring is both protonated and unprotonated. At a pH below the PK a larger fraction is protonated than unprotonated.
2. It is often involved in acid base catalysis.
3. The side chain is good and coordinating metals.

Q

What are the two amino acids with a negatively charged side chain?

A

Q

What is this amino Acid? What type of molecule is it? What’s the pK?

A

D (Asp) Aspartate
Negatively charged side chain
Very hydrophilic
Occur often in active sites.
Can coordinate metals
pK= 3.9

Q

What is this amino Acid? What type of molecule is it? What’s the pK?

A

E (Glu) Glutamate
Negatively charged side chain
Very hydrophilic
Occur often in active sites.
Can coordinate metals
pK= 4.2

Name the 3 amino acids with aromatic side chains. (What two are amphiphilic?)

The two are: Tyrosine and Tryptophan.

What is this amino Acid? What type of molecule is it? What’s the pK? What wave length does it absorb?

F (Phe) Phenylalanine Aromatic side chain pK unimportant. Absorbs at 258 nm.

What is this amino Acid? What type of molecule is it? What’s the pK? What wave length does it absorb?

Y (Tyr) Tyrosine Aromatic side chain pK=10.1 nm not said yet

What is this amino Acid? What type of molecule is it? What’s the pK? What wave length does it absorb?

W (Trp) Tryptophan Aromatic side chain pK unimportant. Nm=unkown rn

What does the amino group look like above the pKa? below?

Above: NH2 Below: NH3+

What does the hydroxyl group look like above the pKa? below?

Above: O- Below: OH

What does the SH group look like above the pKa? below?

Above: S- Below: SH

Test your amino acid memorization.

What does the imidazole group look like above the pKa? below?

What does the Guanidinium group look like above the pKa? below?

True of false: the pKa of the same functional group can be different in different molecules?

True!

What is the chirality of amino acids? Any exceptions?

19 are **L** configuration from their alpha carbon. Glycine isn’t chiral!

Why will you never see proline in the middle of a helics?

Proline is a helix breaker! Proline can’t make H-bonds with another amino acid as the amino group makes a covalent bond with its side chain instead.