Protein 2 Chemistry of amino acida by Dr Ashok Kumar J

1 Dr. Ashok Kumar J; IMS; MSU

Macro

molecules

Amino acid

Polymer of Amino acids

Small Molecules

Biomolecules

2Dr. Ashok Kumar J; IMS; MSU

C

R

NH2C = O O-

General structure of amino acid:

carboxyl groups

Side chain group

Individual amino acids differ from each other with respect to their side chain group

3Dr. Ashok Kumar J; IMS; MSU

Amino acids present in proteins are α - amino acids

4 Dr. Ashok Kumar J; IMS; MSU

D- amino acid L- amino acid

All amino acids present in proteins are L-α-amino acids

All amino acids present in proteins are L-α-amino acids

5 Dr. Ashok Kumar J; IMS; MSU

• About 300 amino acids occur in nature

• Subset of only 20 constitute the monomer units of proteins

“Standard Amino acids”

?

6Dr. ASHOKKUMAR. J.; Professor: Dept. of

Biochemistry.

Glycine Gly G

Alanine Ala A

Valine Val V

Leucine Leu L

Isoleucine Ile I

Serine Ser S

Threonine Thr T

Phenylalanine

Phe F

Tyrosine Tyr Y

Tryptophan Trp W

Glutamate Glu E

Aspartate Asp D

Glutamine Gln Q

Aspargine Asn N

Arginine Arg R

Lysine Lys K

Histidine His H

Cysteine Cys C

Methionine Met M

Proline Pro P7

Dr. ASHOKKUMAR. J.; Professor: Dept. of

Biochemistry.

8Dr. Ashok Kumar J; IMS; MSU

Classification of Amino acids1.Based on the structure

Mono amino Monocarboxylic amino acids

Branched chain amino acids

Simple amino acids

Aromatic amino acids

9 Dr. Ashok Kumar J; IMS; MSU

PHENYLALANINE TYROSINE TRYPTOPHAN

Monoamino monocarboxylic amino acids

Sulfur containing amino acids

10 Dr. Ashok Kumar J; IMS; MSU

METHIONINE CYSTEINE

Monoamino monocarboxylic amino acids

Dr. Ashok Kumar J; IMS; MSU11

Diamino dicarboxylic acidsCystine

Cysteine

Hydroxyl group containing amino acids

12 Dr. Ashok Kumar J; IMS; MSU

SERINE THREONINE

Monoamino monocarboxylic amino acids

Amino acid amides

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ASPARAGINEGLUTAMINE

Monoamino monocarboxylic amino acids

Acidic amino acids

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ASPARTATE

GLUTAMATE

Monoamino dicarboxylic amino acids

Basic amino acids

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HISTIDINE LYSINE ARGININE

Diamino monocarboxylic amino acids

Based on the side chain polarity

Dr. Ashok Kumar J; IMS; MSU16

Based on PolarityNonpolar amino

acids

17 Dr. Ashok Kumar J; IMS; MSU

Alanine

Valine Leucine

Isoleucine

Methionine

Phenylalanine

Tryptophan

Proline

amino acids withpolar sidechain with no charge on the side chain

18 Dr. Ashok Kumar J; IMS; MSU

Glycine

Polar amino acids with – ve or + ve charge

19 Dr. Ashok Kumar J; IMS; MSU

ClassificationBased on the nutritional

requirement

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Dr. Ashok Kumar J; IMS; MSU21

ClassificationBased on the Metabolic fate

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23 Dr. Ashok Kumar J; IMS; MSU

24 Dr. Ashok Kumar J; IMS; MSU

D- amino acids• Actinomycin –D• Valinomycine• Gramicidin –S• D –Glutamic acid & D- Alanine

of bacterial cell wall

25 Dr. Ashok Kumar J; IMS; MSU

Acid – Base Properties of amino acid

Low pH

High pH26

Dr. ASHOKKUMAR. J.; Professor: Dept. of

Biochemistry.

amino acids act both as acid and base depending upon the

surrounding environment

Ampholytes

At isoelectric pH -Minimum solubility-Immobile in the electrical field

+ve charge – pH below the isoelectric pH-ve charge – pH above the isoelectric pH27 Dr. Ashok Kumar J; IMS; MSU

pH at which amino acids have equal number of positive and negative charges is called isoelectric pH [pI]

Thank you

Ref :

Dr. Ashok Kumar J; IMS; MSU28