PROTEIN CHEMISTRY Polypeptide backbone, covalent and non covalent interaction , end group analysis by chemical and enzymatic methods, conformation and configuration
Similar to PROTEIN CHEMISTRY Polypeptide backbone, covalent and non covalent interaction , end group analysis by chemical and enzymatic methods, conformation and configuration
Similar to PROTEIN CHEMISTRY Polypeptide backbone, covalent and non covalent interaction , end group analysis by chemical and enzymatic methods, conformation and configuration (20)
PROTEIN CHEMISTRY Polypeptide backbone, covalent and non covalent interaction , end group analysis by chemical and enzymatic methods, conformation and configuration
1. 3.1 PROTEIN CHEMISTRY
(3.1.1 Polypeptide backbone, covalent and non
covalent interaction , end group analysis by chemical
and enzymatic methods, conformation and
configuration)
PRESENTED BY
JYOTI DEVENDRA ADALA
2. PEPTIDE BOND
Two amino acid molecules
can be covalently joined
through a substituted amide
linkage, termed a peptide
bond, to yield a dipeptide.
3. POLYPEPTIDE BACKBONE
Three amino acids can be joined by two peptide bonds to form a
tripeptide. When a few amino acids are joined in this fashion, the
structure is called an oligopeptide. When many amino acids are
joined, the product is called a polypeptide.
4. Covalent interactions in proteins
A covalent compound is formed by the mutual sharing of electrons among
the combining atoms of the same or different elements. In this process
both atoms attain noble gas configuration.
1) Peptide bond
2) Disulfide bonds
5. Electrostatic Interactions in Proteins
Figure shows an electrostatic interaction between a positively charged lysine amino
group and a negatively charged glutamate carboxyl group.
6. HYDROGEN BONDS IN PROTEINS
A weak electrostatic force of attraction
between the covalently bonded
hydrogen atom of one molecule and a
highly electronegative atom of other
molecule is called hydrogen bond.
This is generally represented by a
dotted line.
7.
8. Hydrophobic interactions in proteins
Interaction between uncharged substituents on different
molecules without a sharing of electrons or protons.
Interaction of (unionizable) hydrocarbon molecules forced
together because of stronger water interaction.
9. Van der Waals forces in proteins
The van der Waals
forces is the sum of the
attractive or repulsive
forces between molecules
(or between parts of the
same molecule with one
another).
10.
11. End group analysis
Number of chains can be determined by
identifying the number of N and C terminal.
N-TERMINAL ANALYSIS
-Dansyl chloride
-Edmans degradation
-Treatment with Sanger reagent
C-TERMINAL ANALYSIS
-Carboxypeptidases
12. Reaction with Dansyl chloride
Dansyl chloride ( 1,1 dimethyl amino
naphalene-5-sulfonyl chloride) reacts with
N-terminal amino acid to form dansyl amino
acid derivative .
13. Edman degradation
This method utilizes
phenylisothiocyanate to react
with the N-terminal residue
under alkaline conditions. The
reaction results in the
released N-terminal residue to
a phenylthiohydantoin
derivative.
Advantage :- The remaining
peptides are intact.
14.
15. Treatment with Sanger’s reagent
Sanger’s reagent is 1-fluoro-2,4-
dinitrobenzene (FNDB). FNDB specifically
binds with N-terminal amino acid to form
dinitrophenyl (DNP) derivative of peptide. On
hydrolysis yield DNP amino acid and free
amino acid from rest of peptide.
16. C- Terminal Analysis
- Carboxypeptidase A: cleaves all except Arg,
Lys, and Proline
– Carboxypeptidase B: cleaves C-terminal
Arg and Lys if the next residue is not Proline.
– Carboxypeptidase C: cleaves C-terminal
residues
17. Any of the spatial arrangements of a molecule that can be
obtained by rotation of the atoms about a single bond. The
alternative structures of the same protein are referred to as
different CONFORMATION.
The CONFIGURATION is a concept that is related to the order
by which different substituents linked to the same central
atom establish covalent bonds.
