amino acids and classification

1. AMINO ACIDS
MADE BY-PRASIDDHI TARE
MADE BY-
PRASIDDHI TARE

2. AMINO ACIDS ARE AMINATED ORGANIC ACID
THEY ARE SUBSTITUTED METHANES ON alpha CARBON,THERE IS
AMINO GROUP AS WELL AS COOH GROUP.
THEY SERVE AS BUILDING BLOCKS OF PROTEIN.
THERE ARE 20 TYPRS OF ALPHA AMINO ACIDS WHICH POLYMERISE
TP FORM PROTEIN.
HOWEVER THERE ARE SOME NON ALPHA AMINO ACIDS AS WELL
BUT THEY DO NOT OCCUR IN PROTEIN.
EACH AMINO ACID HAS SAME FUNDAMENTAL STRUCTURE WHICH
CONSISTS OF CENTRAL CARBON ATOM.
AMINO ACIDS ARE AMPHIPROTIC MOLECULES

4. CLASSIFICATION OF AMINO ACIDS
• BASED ON NUTRITIONAL IMPORTANCE
• BASED ON POLARITY
• BASED ON THEIR METABOILIC FATE
• BASED ON THEIR STRUCTURE
• BASED ON TWO MAIN GROUP OF AMINO ACIDS

5. NUTRITIONAL CLASSIFICATION
ON THE BASIS OF NUTRITIONAL IMPORTANCE AMINO ACIDS ARE
CLASSIFIED INTO TWO CATEGORIES-
ESSENTIAL AMINO ACIDS –
THOSE AMINO ACIDS WHICH ARE NOT SYNTHESISED IN OUR BODY AND ARE
REQUIRED WITH DIET ARE KNOWN AS ESSENTIAL AMINO ACIDS .
THERE ARE 10 ESSENTIAL AMINO ACIDS –,
THREONININE,ISOLEUCINE,LYSINE,TRYPTOPHAN,METHONI,
VALINE,PHENYLALANINE,LEUCINE.

6. NON ESSENTIAL AMINO ACIDS-
THOSE AMINI ACIDS WHICH CAN BE SYNTHESISED IN OUR BODY ARE KNOWN AS
NON ESSENTIAL AMINO ACIDS.
FOR EXAMPLE-
GLYCINE, ALANINE,CYSTINE,ASPARTACIC ACID.

7. BASED ON POLARITY
• .•There are 4 main classes of amino acids based on polarity, i.e. the interaction of the R group with water molecules at
physiological pH.
1.Amino acids with non-polar (hydrophobic) side chain
•These amino acids have a non–polar hydrophobic side chain. They do not provide protons or participate in hydrogen or
ionic bonding.
•E.g.: alanine, valine, leucine, isoleucine, proline, phenylalanine, tryptophan and methionine.
2.Amino acids with uncharged polar side chains (- R group)
•These amino acids are more soluble in water. They are hydrophilic in nature. The functional groups can make hydrogen
bonds with water.
• E.g.: glycine, serine, threonine, tyrosine, cysteine, asparagine and glutamine.
•The polarity of serine, threonine is due to the presence of hydroxyl groups; the polarity of asparagine and glutamine is due
to the amide group and the sulfhydryl group (thiol group) is responsible for cysteine.
.

8. ..
3.Amino acids with polar, negatively charged side chain
•These amino acids will have a net negative charge at neutral pH.
•E.g.: aspartic acid and glutamic acid.
•These amino acids will have one more carboxyl group, which contribute to negative charge at neutral pH.
4.Amino acids with polar, positively charged side chain
•These amino acids will have a net positive charge at pH 7. They accept protons.
•E.g.: lysine, arginine and histidine.
•Lysine contains a second amino group at ε - position on the aliphatic side chain. Arginine contains a positively
charged guanidino group and histidine contains an imidazole group

9. BASED ON THEIR METABOILIC FATE
• Amino acids are classified as glucogenic or ketogenic
• Glucogenic amino acids are degraded to compounds that can be used
as carbon skeletons for glucose synthesis via gluconeogenesis.
• Ketogenic amino acids are degraded to compounds that can only be
used to generate the ketone bodies.
• Both Glucogenic and ketogenic amino acids: Several amino acids are
classified as both glucogenic and ketogenic because of their
degradation products.

10. Glucogenic Amino Acids
• Metabolized to α-ketoglutarate, pyruvate, oxaloacetate, fumarate, or succinyl
CoA Phosphoenolpyruvate Glucose
• Phosphoenolpyruvate Glucose
•• Aspartate • Methionine • Alanine • Aspartate • Asparagine
• Arginine • Phenylalanine • Tyrosine • Isoleucine •
Methionine • Valine • Glutamine • Glutamate • Proline •
Histidine • Alanine • Serine • Cysteine • Glycine • Threonine
• Tryptophan

11. Ketogenic Amino Acids
• Metabolized to acetyl CoA or acetoacetyl CoA Animals cannot convert
acetyl CoA or 9 acetoacetyl CoA to pyruvate
•• Leucine * • Lysine * • Tryptophan • Phenylalanine • Tyrosine
•Isoleucine • Threonine
• * Leucine and lysine are only ketogenic

12. BASED ON STRUCTURE
• ACIDIC AMINO ACIDS-
(a)Aspartic acid –(d) b Glutamic acid(e)
• BASIC AMINO ACIDS-
(a)Lysine (k) b Arginine(k)

13. .
• NEUTRAL AMINO ACIDS WITH ALIPHATIC SIDE CHAIN-

14. .

15. • AMINO ACIDS WITH AROMATIC SIDE CHAIN-
1.Tryptophan(w) 2.Tyrosine(y)
3.Phenylalanine(f) 4.Histidine(h)

16. .
•ALCOHOLIC AMINO ACIDS –
1.Serine(s) 2.Threonine(t)
•SULPHUR CONTAINING AMINO ACIDS –
1.Cystine (c) 2.Methonine(m)

17. .
•AMIDE-
1.Aspargine(N) 2.Glutamine(Q)
•IMINO ACID-
1.Proline(P)

18. .-
Full Name Abbreviation (3 Letter) Abbreviation (1 Letter)
Alanine Ala A
Arginine Arg R
Asparagine Asn N
Aspartate Asp D
Aspartate or Asparagine Asx B
Cysteine Cys C
Glutamate Glu E
Glutamine Gln Q
Glutamate or Glutamine Glx Z
Glycine Gly G
Histidine His H
Isoleucine Ile I
Leucine Leu L
Lysine Lys K
Methionine Met M
Phenylalanine Phe F
Proline Pro P
Serine Ser S
Threonine Thr T
Tryptophan Trp W
Tyrosine Tyr Y
Valine Val V

19. CLASSIFICATION BASED ON TWO MAIN GROUP OF
AMINO ACID
• STANDARD AMINO ACIDS-
Amino acids are the structural units (monomers) that make up proteins. They join together to form
short polymer chains called peptides or longer chains called either polypeptides or proteins. These
polymers are linear and unbranched, with each amino acid within the chain attached to two neighboring
amino acids. The process of making proteins encoded by DNA/RNA genetic material is
called translation and involves the step-by-step addition of amino acids to a growing protein chain by
a ribozyme that is called a ribosome.[48] The order in which the amino acids are added is read through
the genetic code from an mRNA template, which is an RNA copy of one of the organism's genes.
There are total 20 standard amino acids.
Eg.aspartacic acid,valine,isoleucine,etc
• NON STANDARD AMINO ACIDS
• A modified form of methionine (N-formylmethionine) is often incorporated in place of methionine as the
initial amino acid of proteins in bacteria, mitochondria and chloroplasts. Other amino acids are
called nonstandard or non-canonical. Most of the nonstandard amino acids are also non-proteinogenic
(i.e. they cannot be incorporated into proteins during translation), but two of them are proteinogenic, as
they can be incorporated translationally into proteins by exploiting information not encoded in the
universal genetic code.
Eg.hydroxyproline,hydroxylysine.

20. Properties of amino acids-
• Physical properties-
1. Solubility: Most of the amino acids are usually soluble in water, and insoluble in organic
solvents.
2. Melting Point: Amino acids are generally melt at higher temperature of ten above 2000C.
3. Taste: Amino acids may be sweet (Gly, Ala & Val), tasteless (Leu) or Bitter (Arg & Ile).
4. Optical Properties: All amino acids possess optical isomers due to the presence of asymmetric
α-carbon atoms.EXCEPTION-Glycine.
5. Zwitter ion and Isoelectric point: The name zwitter is derived from the German word which
means “hybrid”. Zwitter ion (or) dipolar ion is a hybrid molecule containing positive & negatively
ionic groups. Basically the proton shifts from carboxyl group to amino group of the self-molecule
at normal pH cellular levels.
6. Titration Curve of Glycince: Glycine is optically inactive, simplest amino acid because which
have no asymmetric carbon atom. Acid-Base titration involves the gradual addition (or) removal
of protons. It has three different stages when the Glycine undergoes acid-base titration.

21. Chemical properties
Chemical reactions of amino acids due to carboxyl and amino group
1.Ninhydrin reaction:
Step1: Ninhydrin (=indane 1,2,3-trione hydrate) is a powerful oxidizing agent and causes oxidative decarboxylation of α-amino acids producing
CO2, NH3 and an aldehyde with one less carbon atom than the parent amino acid.

22. .• Step2: The reduced ninhydrin then reacts with the liberated NH3 and a mole of ninhydrin, forming Bluecolored Rhumann’s complex
This reaction is very sensitive reaction and it is used for amino acid and imino acid identification. When Amino acids (or) Imino
acid reacts with Ninhydrin molecule it gives Color. When it gives Purple color (Rhumann’s Complex) –the Unknown sample is
Amino acids (Which have primary amine – NH2) or it is gives Yellow color – the Unknown sample is Imino acid (-NH-).

23. .Reaction with Amines:
• Amino acid reacts with Amines to form “Amides”.
• REACTION WITH AMMONIA
Aspartic acid+NH3 Aspargine
• Reaction with Alcohols (Esterification) :
When the amino acids is reacted with alcohol to form, “Ester”. The esters are volatile in contrast
to the form amino acids.

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