BIOCHEM 4 - AMINO ACIDS Flashcards by J G

Essential Amino acids

L, I, V, H, K, M, F, T, W

How well did you know this?

Not at all

Perfectly

Non-essential amino acids

A, R, N, D, C, E, Q, G, P, S, Y

How well did you know this?

Not at all

Perfectly

aa (obtained from nutrition)

Essential Amino acids

How well did you know this?

Not at all

Perfectly

aa (synthesized by the body)

Non-essential amino acids

How well did you know this?

Not at all

Perfectly

properties of AA (4)

Amphoteric
dipolar
optically active
tetrahedral structure

How well did you know this?

Not at all

Perfectly

– reference to determine if the

amino acid has L- or D-configuration

α-amino group

How well did you know this?

Not at all

Perfectly

All amino acids in naturally occurring proteins are

L-isomers

How well did you know this?

Not at all

Perfectly

◦ derived from glutamate; neurotransmitters (has something to do with the brain)

GABA

How well did you know this?

Not at all

Perfectly

GABA is derived from

glutamate

How well did you know this?

Not at all

Perfectly

◦ derived from tryptophan; important in sleep

Serotonine

How well did you know this?

Not at all

Perfectly

serotonine derived from

derived from tryptophan

How well did you know this?

Not at all

Perfectly

Thyroxine

derived from tyrosine

How well did you know this?

Not at all

Perfectly

indole acetic acid

Dopamine –

How well did you know this?

Not at all

Perfectly

– side chain is a primary alcohol; looks like Ala with -OH

Serine

How well did you know this?

Not at all

Perfectly

side chain is a secondary alcohol;

◦ Threonine

How well did you know this?

Not at all

Perfectly

has two chirality centers

threonine and isoleucine

How well did you know this?

Not at all

Perfectly

contains a thiol group; important in disulfide linkages; weak acid; can form H-bonds

◦ Cysteine

How well did you know this?

Not at all

Perfectly

ionized cysteine is —–, while the protonated form is much ——–than serine.

polar

less polar

How well did you know this?

Not at all

Perfectly

also has the ability to form covalent bonds called disulfide bonds between cysteine side chains.

Cysteine

How well did you know this?

Not at all

Perfectly

– side chain is phenolic –OH; borderline case

Tyrosine

How well did you know this?

Not at all

Perfectly

not very soluble in water, but contains a polar hydroxyl group in the para position of the phenyl ring

Tyrosine

How well did you know this?

Not at all

Perfectly

amide groups do not become charged at biologically relevant pH values (i.e. pH 2-12), true or false

TRUE

How well did you know this?

Not at all

Perfectly

simplest amino acid

GLYCINE

How well did you know this?

Not at all

Perfectly

does not really have a polar or non-polar character

GLYCINE

How well did you know this?

Not at all

Perfectly

- has much less steric hindrance than the other AAs;

GLYCINE

No chiral center/achiral

GLYCINE

no asymmetric carbon

GLYCINE

– side chain is isopropyl

Valine

side chain is isobutyl

Leucine

side chain is sec-butyl; has 2 chiral carbons

Isoleucine –

more hydrophobic than cysteine (S-containing amino acids)

Methionine

start amino acid

Methionine

having thioether

Methionine

– cyclic but not aromatic; 2ndary α-amino group or α-imino acid - has a conformationally restricted structure

Proline

behaves more like a polar amino acid since ----- has a fairly high tendency to appear on the solvent-exposed surface of proteins

proline

– has an indole ring; borderline hydrophobic/polar

Tryptophan

what AA has the proton attached to the indole nitrogen can act as a hydrogen bond donor to water or other hydrogen bond acceptors

Tryptophan

majority of the large tryptophan side-chain is polar or not?.

non-polar

acidic form of asparagines; β-carboxyl group

Aspartate-

acidic form of glutamine; γ-carboxyl group

Glutamate–

– has a primary amino group | protonated at pH 7.0

◦ Lysine

contains ε-amino group

◦ Lysine

diamino acid

◦ Lysine

– most basic amino acid

Arginine

contains guanido group

Arginine

guanidinium ion always protonated

Arginine

heterocyclic ring side chain; not aromatic

Histidine

contains imidazole

Histidine

only amino acid that functions as buffer in physiological range

Histidine

all are very hydrophobic absorbs UV at 280 nm aromatic amino acids

Tyrosine, Tyr (Y) Tryptophan, Trp (W) Phenylalanine, Phe (F)

contain carboxyl groups (weaker than α-carboxyl group) | negatively charged at physiological pH;

Aspartate, Asp (D) | Glutamate, Glu (E)

present as conjugate bases | carboxyl groups function as nucleophiles in some enzymatic reactions

Aspartate, Asp (D) | Glutamate, Glu (E)

classified as β-branched have greater steric hindrance exhibit more restricted conformational flexibility

Valine, Val (V) Isoleucine, Ile (I) Threonine, Thr (T)

18 of the 19 L-amino acids have --- configuration

cysteine has -- configuration

is neither very | hydrophobic nor very hydrophilic.

Proline

As the pH increases, the charge on the molecule becomes

more negative,

as the pH decreases, | the charge on the molecule becomes

more positive.

zero net charge state is known as the

zwitterionic state

is capable of both accepting | and donating protons

zwitterion

characteristic of free amino acids with non-ionizable side chains near pH 7.0

zwitterion

At pH >> pKa, the ionizable group will be . | -

deprotonated

At pH >> pKa, For carboxylic acids, the group will be ____ charged;

negatively

At pH >> pKa, amines will be ____

neutral

At pH << pKa, the ionizable group will be _______

protonated.

At pH << pKa, For carboxylic acids, the group will be __

neutral

At pH << pKa, amines will be _____

positively charged

has a chemically basic side chain but acidic pKa

histidine

pKa values of amino groups of common AA

occur in a range from pH 9 to pH 11

pKa values of carboxyl groups of common AA

ph 2