amino acids

Slide 1: 

Amino acids Mrs. Rani ashok Asst. prof. of zoology Lady doak college, madurai – 2 Email: eaarani@rediffmail.com

Amino Acids : 

Amino Acids Structural units that make up proteins Intermediates of metabolism Twenty standard amino acids used by cells in protein biosynthesis, and these are specified by the general genetic code Chemical properties of Amino acids determine the biological activity of a protein

AMINO ACIDS … : 

AMINO ACIDS … 2 types: Essential & Non-essential Essential / Indispensible– Not synthesized by body; Supplied in diet Non-essential – Synthesized by body

AMINO ACIDS IN HUMANS : 

AMINO ACIDS IN HUMANS Eight essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.  The twelve non-essential amino acids are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, arginine, histidine, and tyrosine.  Cysteine, tyrosine, histidine and arginine are semi essential amino acids in children, because the metabolic pathways synthesizing these amino acids are not fully developed.

AMINO ACID STRUCTURE : 

AMINO ACID STRUCTURE It is a molecule that contains both amino (NH2) and carboxyl (COOH) functional groups

AMINO ACIDS : 

AMINO ACIDS Exist in either D (dextro) or L (levo) form (stereoisomers). Extremely crucial for good health. Amino acids contribute significantly to the health of the nervous system, muscular structure, hormone production, vital organs and cellular structure. Low levels of the essential amino acids result in hormonal imbalances, irritability, low concentration, and depression .

Slide 8: 

In body mainly “l” form of amino acid is seen “d” form is seen in bacteria & some antibiotics

CHARACTERIZATION OF AMINO ACID : 

CHARACTERIZATION OF AMINO ACID

Characterization of Free Aminoacids – NINHYDRIN REACTION : 

Characterization of Free Aminoacids – NINHYDRIN REACTION

Characterization of Bound Aminoacids – BIURET REACTION : 

Characterization of Bound Aminoacids – BIURET REACTION

Other colour reactions : 

Other colour reactions Certain amino acids can also be identified with specific color reagents. When histidine reacts with diazosulfanilic acid a cherry red color is observed.

Xanthoprotein test : 

Xanthoprotein test

Hopkins – Cole Test : 

Hopkins – Cole Test

Nitroprusside Test : 

Nitroprusside Test

SULFUR TEST : 

SULFUR TEST The presence of sulfur-containing amino acids such as cysteine can be determined by converting the sulfur to an inorganic sulfide through cleavage by base. When the resulting solution is combined with lead acetate, a black precipitate of lead sulfide results. Sulfur-containing protein  ----NaOH---->  S2- ----Pb2+---->  PbS

PROPERTIES OF AMINO ACID : 

PROPERTIES OF AMINO ACID

Slide 18: 

A Venn diagram showing the relationship of the 20 naturally occurring amino acids to a selection of physio-chemical properties thought to be important in the determination of protein structure

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The amino acid occurrence statistics were compiled using the NCBI database.

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Optical Isomerism

Ramachandran Plot : 

The classical version of the Ramachandran plot for (a) alanine (but often taken as typical for all non-glycines) and (b) glycine according to Ramachandran & Sasisekharan (1968). The fully allowed regions are shaded; the partially allowed regions are enclosed by a solid line. The connecting regions enclosed by the dashed lines are permissible with slight flexibility of bond angles. These plots were arrived at by stereo-chemical modelling. Although some overall features of these plots are correct, the details differ from the experimentally observed Ramachandran plots for (c) all 19 non-glycines and (d) glycine. The most remarkable differences are that most regions show a 45 degree slope rather than being parallel to any of the axes, the beta sheet region is split into two distinct maxima and the two most populated regions (red) for glycine seen in (d) were predicted to be only just permissible as shown in (b). There are five areas in the glycine plot; two with psi 0 and three with psi 180. Referenced from Hovmöller (2002) Ramachandran Plot

CLASSIFICATION OF AMINO ACID : 

Amino Acids are classified based on R or side chain group Polarity of side chain Number of amino and carboxyl group CLASSIFICATION OF AMINO ACID

GROUPS IN AMINO ACID : 

GROUPS IN AMINO ACID

AMINO ACID IN PROTEIN FORMATION : 

AMINO ACID IN PROTEIN FORMATION

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A diagram showing the bond angles, bond lengths and general geometry of a peptide bond. Bond angles are given in degrees.

Common Postranslational Modifications : 

Common Postranslational Modifications

GENETIC CODE – Canonical codes : 

GENETIC CODE – Canonical codes

GENETIC CODE - Non-canonical codes in eubacterial genomes : 

GENETIC CODE - Non-canonical codes in eubacterial genomes Micrococcus luteus AGA = Not usable ATA = Not usable Kanoi et al , J Mol Biol 230, 51-6 (1993) Mycoplasmas and Spiroplasmas TGA = Trp Inamine et al J Bacteriol 172: 504-506 (1990) CGG = Not usable Oba et al Proc Natl Acad Sci U S A 88: 921-5 (1991)

GENETIC CODE - Non-canonical codes in eukaryotic nuclear genomes : 

GENETIC CODE - Non-canonical codes in eukaryotic nuclear genomes

GENETIC CODE - Non-canonical codes in mitochondrial genomes : 

GENETIC CODE - Non-canonical codes in mitochondrial genomes

AMINO ACID SYNTHESIS : 

AMINO ACID SYNTHESIS

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Thank You