Amino Acids and it's classification

Amino acid:

An amino acid is the basic molecule of proteins. It is structural and functional unit of proteins. It has four different functional  groups attached to the central carbon atom. It general structure contains one carboxyl group(-COOH), one amino group(-NH2), one alkyl group(-R) and one Hydrogen atom.

General structure:

Note: Alkyl group of amino acid either may have aliphatic or aromatic chains.
[e.g-alanine(CH3-as R-groups),Phenylalanine(CH3+Benzene ring)]

There are total 20 common amino acids that encodes for protein synthesis. (Exception: Selenocysteine -21st Amino acid is derivative of cysteine contains selenium rather than sulfur. While pyrrolysine -22nd amino acid that means lysine contains pyrrole ring.

Classification of Amino acid:

Amino acid can be classified based on their:

(I) Location of amino group (-NH2).
(II) Polarity
(III) Nutritional value
(IV) Metabolic rate
(V) structure

(I) Based on the location of amino group(-NH2)

(II)Based on Polarity : 

A.A classified into 4
different categories.
(a) Nonpolar A.A.
(b) Polar A.A with No charge on R-groups.
(c) Polar A.A with +ve R groups.
(d) Polar A.A with -ve R groups.

              (a)Nonpolar Amino acid

	Non Polar A.A
Aliphatic R Groups		Aromatic R Groups
Glycine (G)		Phenylalanine (F)
Alanine (A)		Tryptophan (W)
Valine (V)
Leucine (L)
Isoleucine (I)
Proline (P)
Methionine (M)

             (b) Polar A.A with No charge on R groups

Sr. NO:	Amino Acid
1	Glycine (G)
2	Serine (S)
3	Threonine (T)
4	Cysteine (C)
5	Tryptophan (W)
6	Asparagine (N)
7	Glutamine(Q)
8	Tyrosine (Y)
Mnemonics	whY GST Comes Without Notice ?(Question mark)

            

 (c) Polar with +R groups

Sr. NO:	Amino Acid
1	Lysine(K)
2	Arginine(R)
3	Histidine(H)

             

(d) Polar with -R groups

Sr. NO:	Amino Acid
1	Proline (P)
2	Aspartic Acid(D)

(III)Based on Nutritional Value
     (a) Essential: A.A that cannot be systhesize by our body, only taken as diets.

     (b)Semi-essential: A.A that can synthesize in adults but not in growing children.

      (c) Non-essential: A.A that can synthesize in our body and doesn't require to take from outside as in diets.

	Based on Nutritional Value
Essential A.A	Semi- Essential A.A	Non-Essential A.A
Methionine (M)	Histidine (H)	Glycine (G)
Phenylalanine (F)	Arginine (R)	Alanine (A)
Isoleucine (I)		Proline (P)
Lysine (K)		Serine (S)
Leucine (L)		Cysteine (C)
Valine (V)		Aspartic Acid (D)
Tyrosine (Y)		Glutamic Acid (E)
Threonine (T)		Glutamine (Q)
Tryptophan (W)		Asparagine (N)

(IV) Based on Metabolic Rate
   (a)Glycogenic A.A: Precursor for the formation of glucose or glycon.

   (b) Ketogenic A.A: Fats can be synthesized from these amino acids and it's precursor.

   (c) Glycogenic & Ketogenic A.A:  Four A.A are precursor for the synthesis of glucose and fats.

	Based on Metabolic Rate
Gluconic A.A	Ketonic A.A	Gluconic & Ketonic A.A
Glycine (G)	Lysine (K)	Isoleucine (I)
Alanine (A)	Leucine (L)	Phenylalanine (F)
Methionine (M)		Tryptophan (W)
Aspartic Acid (D)		Tyrosine (Y)
Mnemonics: GAMD	Mnemonics: KL-Rahul	Mnemonics: WIFY

(V) Based on Structure 

   (a) A.A with Aliphatic side chain

Sr. NO:	Amino Acid
1	Glycine (G)
2	Alanine (A)
3	Valine (V)
4	Leucine (L)
5	Isoleucine (I)

      

(b) A.A containing -OH groups.

Sr. NO:	Amino Acid
1	Threonine (T)
2	Serine (S)
3	Tyrosine (Y)

      

(c) A.A containing Sulfur groups

Sr. NO:	Amino Acid
1	Methionine (M)
2	Cysteine (C)
3	Cystine

       

 (d) Acidic A.A with their amides 

Sr. NO:	Amino Acid
1	Aspartic Acid(D)
2	Glutamic Acid (E)
3	Asparagine (N)
4	Glutamine(Q)

      

   (e) Basic A.A

Sr. NO:	Amino Acid
1	Lysine(K)
2	Arginine(R)
3	Histidine(H)

      

   (f) Aromatic A.A

Sr. NO:	Amino Acid
1	Phenylalanine (F)
2	Tyrosine (Y)
3	Tryptophan (F)

   (g) Imino group A.A

Sr. NO:	Amino Acid
1	Proline (P)

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