By Dr Mehnaz Kamal Assistant Professor Pharmaceutical Chemistry Prince Sattam Bin Abdulaziz University WELCOME Amino acids 1To know what is protein 2To identify Types of ID: 779431
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Slide1
Pharmaceutical Organic Chemistry
By
Dr.
Mehnaz
Kamal
Assistant Professor,
Pharmaceutical Chemistry
Prince
Sattam
Bin
Abdulaziz
University
Slide2WELCOME
Slide3Amino acids
Slide41-To know
what is protein
2-To identify Types of
protein
3- To Know
amino acids
4-
To
differentiate between
essential and nonessential amino acids5-To understand amino acids synthesis
Slide5Characteristics and Structures
Amino Acids
All three groups are attached to a single carbon atom called chiral carbon. There are 20 common amino acids
characterised
by different R groups.
(
Different
side chains make different amino
acids)
Amino acids are the building blocks of proteins. Each amino acid contains :1.Amino group (-NH2 group)2.Carboxyl group (-COOH group)3.R group (side chain) which determines the type of an amino acid
Slide6Ball and stick model
Other
amino acids also exist called beta and gamma amino acids, in which the amino group is attached to the carbon which is next to α carbon called α amino
acid
The amino group is attached to the carbon atom immediately next to the carboxylate group that is α carbon, so, it is called α amino acids
Amino Acids
Slide7α
-Amino
Acids
α
-
Amino Acids
have the amino group
α
(on
the next carbon) to the
carbonyl
group
.
a
carbon
α
-
Amino acids are classified as
neutral
,
acidic
,
basic
,
primary
, and
secondary
, depending on the
R
group.
Amino Acids
Slide8α
-Amino
acids are
neutral
,
acidic
, or
basic
.
neutral
alanine
acidic
aspartic acid
basic
lysine
Amino Acids
Slide9Most
α
-amino
acids are
primary
, few are
secondary
.
primary
alanine
secondary
proline
Amino Acids
Slide10all others are optically active
(they are
chiral)
L-amino
acids are naturally occurring
absolute configuration is S
Optical Activity
Only glycine is not optically active
Amino Acids
Slide11Zwitterions
A Zwitterion is a dipolar ion. Since amino acids contain both an
acid
and a
base
,
an internal acid-base reaction forms a
zwitterion
.
amino acid
zwitterion
Amino acids exist primarily as
zwitterions
.
Amino Acids
Slide12Amino acid zwitterions are
amphoteric
.
They can react as either
acids
or
bases
.
In acid solution
In base solution
zwitterion
protonated
zwitterion
deprotonated
Amino Acids
Slide13Isoelectric Points
The
isoelectric point
of an amino acid occurs at the
pH
where the amino acid exists as the
zwitterion
.
deprotonated
base solution
high pH
protonated
acid solution
low pH
zwitterion
isoelectric point
Amino Acids
Slide14There are 20 amino acids derived from proteins.
While
there are several methods of categorizing
them.
one of the most common is to group them according to the
nature of their side chains.
1-Nonpolar Side Chains
2-Polar
, Uncharged Side Chains 3- Polar Amino Acids with Negative Charge4-Polar Amino Acids with Positive ChargeAmino Acids
Slide15*
Phenylalanine
,
valine
, leucine, isoleucine, and methionine
(have
larger side chains and are more strongly hydrophobic).
1- Nonpolar Side Chains
*Glycine, alanine, and proline (have small, nonpolar side chains and are all weakly hydrophobic).Amino Acids There are eight amino acids with nonpolar side chains
Non Polar Amino Acids have equal number of amino and carboxyl groups and are neutral
Slide16These amino acids do not have any charge on the 'R' group. These amino acids participate in hydrogen bonding of protein
structure
There
are also eight amino acids with polar, uncharged side chains
.
Serine and threonine
have hydroxyl groups. Asparagine and glutamine have amide groups.Histidine
and tryptophan
have heterocyclic aromatic amine side chains.Cysteine has a sulfhydryl group. Tyrosine has a phenolic side chain.2- Polar, Uncharged Side Chains Amino Acids
Slide17Tryptophan
Slide18*
Arginine
and
lysine
have side chains with amino groups.
3- Polar Amino Acids with Negative Charge
There are four amino acids with charged side chains.
*
Aspartic acid and glutamic acid have carboxyl groups than amino groups on their side chains making them acidicAmino Acids
more amino groups as compared to carboxyl groups making it basic
4-Polar
Amino Acids with Positive Charge
Slide19Linear Structure
Abbreviation
Name
CH3-CH(NH2)-COOH
ala A
Alanine
HN=C(NH2)-NH-(CH2)3-CH(NH2)-COOH
arg R
Arginine
H2N-CO-CH2-CH(NH2)-COOH
asn
N
Asparagine
HOOC-CH2-CH(NH2)-COOH
asp D
Aspartic Acid
HS-CH2-CH(NH2)-COOH
cys C
Cysteine
HOOC-(CH2)2-CH(NH2)-COOH
glu E
Glutamic Acid
H2N-CO-(CH2)2-CH(NH2)-COOH
gln Q
Glutamine
NH2-CH2-COOH
gly G
Glycine
N
H-CH=N-CH=
C
-CH2-CH(NH2)-COOH
his H
Histidine
CH3-CH2-CH(CH3)-CH(NH2)-COOH
ile I
Isoleucine
Slide20Linear Structure
Abbreviation
Name
(CH3)2-CH-CH2-CH(NH2)-COOH
leu L
Leucine
H2N-(CH2)4-CH(NH2)-COOH
lys K
Lysine
CH3-S-(CH2)2-CH(NH2)-COOH
met M
Methionine
Ph-CH2-CH(NH2)-COOH
phe F
Phenylalanine
N
H-(CH2)3-
C
H-COOH
pro P
Proline
HO-CH2-CH(NH2)-COOH
ser S
Serine
CH3-CH(OH)-CH(NH2)-COOH
thr T
Threonine
Ph
-NH-CH=
C
-CH2-CH(NH2)-COOH
trp W
Tryptophan
HO-Ph-CH2-CH(NH2)-COOH
tyr Y
Tyrosine
(CH3)2-CH-CH(NH2)-COOH
val V
Valine
Slide21Importance of Amino Acids
Amino acids combine into small chains via chemical reactions
called
‘condensation reactions’
in which the carboxyl group and the amino group bond to one another. These small chains that contain a few amino acids linked together are called polypeptide chains (the individual amino acids are called petides).
Polypetide chains, in turn, combine into the more complex structures known as proteins Amino acids are the building blocks of protein and you get protein from your diet.
If you eat a variety of healthy protein-containing foods,
you will get all of the nine essential amino acids that your body can't make for itself.Amino Acids
Slide22Amino acids can be found in most of the nutrients we eat. Amino acids are the building blocks of healthy protein. If the food consumed is rich in protein, our body digests the protein right down to individual amino acids and little links of amino acids is adequate to be taken over into the blood stream
Amino Acids
Slide23There are nine amino acids that cannot be synthesized in the body. H
istidine
, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine
. We need these amino acids in specific amounts daily in our diet.
Essential
amino acids
Amino Acids
PVT
TIM
HLL
Slide24Non Essential amino acids
Amino Acids
Seven
of them
considered conditionally essential
in the human diet, meaning their synthesis can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic
distress (
These
seven are arginine, cysteine, glycine, glutamine, serine, proline and tyrosine)One of 11 amino acids that are synthesized in the body and are therefore not necessary in the diet. Four amino acids are dispensable in humans, meaning they can be synthesized in the body. These four are alanine, aspartic acid, asparagine and glutamic acid.Ornithine is 21st amino acid. Pyrrolysine, sometimes considered "the 22nd amino acid", is not listed here as it is not used by humansArginine is essential for infants but not for adults.
Slide25The Eleven "Nonessential" Amino Acids
Alanine
Asparagine
Aspartate
Cysteine
(requires sulfhydryl group from methionine)
Glutamate
Glutamine
Glycine
Proline
Serine
Tyrosine
(synthesized from phenylalanine)
The Nine "Essential" Amino Acids
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Amino Acids
Arginine
Slide26Amino Acids
The result is the formation of a peptide or a protein, depending upon how many amino acids there are.
Therefore, it should be possible to link amino acids together through the formation of amides.
As can be seen, the amino acids possess both functional groups required to form an amide. Each amino acid is both a carboxylic acid and an amine simultaneously
.
Peptides are named according to the number of amino acids that are linked:
dipeptide: two amino acids
tripeptide
: three amino acids
tetrapeptide
: four amino acids
Polypeptide - < 50 amino acids
Proteins-polymers of > 50 amino acids
Peptides and Proteins
Amino Acids
Slide28Amino Acids
Synthesis of amino acids
Strecker
amino-acid synthesis
is a series of chemical reactions that synthesize an amino acid from an aldehyde or ketone
The
aldehyde
is condensed with
ammonium chloride
in the presence of potassium cyanide to form an α-aminonitrile, which is subsequently hydrolyzed to give the desired amino-acid.
Slide29Amino Acids
Reaction mechanism
*
In
the first part of the reaction, the
carbony
l oxygen of an aldehyde is protonated,
*followed
by
a nucleophilic attack of ammonia to the carbonyl carbon. *After subsequent proton exchange, water is cleaved from the iminium ion intermediate. *A cyanide ion then attacks the iminium carbon yielding an aminonitrile.First part
Slide30Amino Acids
Reaction mechanism
*
the
nitrile nitrogen of the
aminonitrile is protonated, and the
nitrile carbon is attacked by a water molecule. * 1,2-diamino-diol is then formed after proton exchange and a nucleophilic attack of water to the former nitrile carbon. *Ammonia is subsequently eliminated after the protonation of the amino group, and finally the
deprotonation
of a hydroxyl group produces an
amino acid.second part
Slide31Linkage with the life sciences
Information Enrichment
Slide32Protein Digestion: Part 1
Slide33Protein Digestion: Part 2
Figure 6.6
Slide34Protein Digestion: Part 3
Figure 6.6
Slide35Protein Digestion: Part 4
Figure 6.6
Slide36If amino acid supply is inadequate to meet your body’s needs, a whole host of important functions can begin to suffer.This results in the appearance of signs and symptoms ranging from immune system effects to cardiovascular disease to emotional disorders and more.Typical
symptoms I see when folk are deficient in amino acids include:
•Low energy levels (even chronic fatigue)
•Depression
•Anxiety
•Memory and concentration problems•Low thyroid function (which affects everything!)•Allergic symptoms•Digestive symptoms•Inability to detoxify properly•Loss of muscle mass•Increased body fat
Possible symptoms of amino acid deficiencies and imbalances
Slide37