Complexation and protein binding

B,Pharmacy III sem

1. Kiran C Rodge
Shivlingeshwar college of Pharmacy,
Almala,
Tq-Ausa,Dist-Latur,Maharashtra
COMPLEXATION
&
PROTEIN BINDING

2. Complex Compound
Those molecules in which most binding structures can be described
by classical valence theories between atoms but one or more of these
bonds are somewhat anomalous.
Complexation
It is association between two or more molecules to form a non covalent
Bonded Entity with a defined stoichiometry .
Ligands
The ligand is a molecule that interacts with another molecule by
co-ordinate bonds and form a complex.

3. Metal Complex
It consist of a central metal atom or ion that is bonded to one or more
ligand.
Coordination number
It is defined as the total number of ligands attached to a central metal
ion/atom .
Protein Binding
It is the phenomenon of complex formation of drugs with proteins.

4. Complex formation process
The filled ligand orbital overlap the empty metal ion orbital
The ligand (Lewis base) donates the electron pair
The metal ion (Lewis acid) accepts it
Form one of the coordinate bonds of the complex ion

5. Ligands
1. Unidentate (NH3)
2. Bidentate (Ethylenediamine)
3. Polydentate (EDTA)

6. EDTA Binding sites

7. Application of Chelating Agent

8. Classification of Complexation

9. Metal Complexes
These types of complexes are consist of central metal ion
That is bonded one or more ligands.
Ligands are molecule that contain one or more pair of
electron that can be sheared with metal.
Metal complex can be neutral, positively or negatively
charged.

10. Inorganic Metal Complexes

11. Chelates

12. Olefin Complexes

13. Aromatic Complexes

14. Organic Molecular Complexes
These types of complexes are formed by noncovalent int
eraction between ligands and substrate & held together
by weaker forces or Hydrogen bonding..

19. Inclusion Complexes
These complexes are also called occlusion compounds in
which one of the components is trapped in the open
lattice or cage like crystal structure of the other..

24. Methods of Complexation Analysis
Method of Continuous variation
pH titration Method
Distribution Method
Solubility Method
Spectroscopy & charge transfer
Miscellaneous

25. Method of Continuous variation

In this we measured additive property.
JOB suggested the use of additive property such as dielectric
constant ,Absorbance etc..
 If the property for two species is different and when they are
mixed no interaction is occur
If the additive property such as dielectric constant is plotted Vs
mole fraction from 0-1 , If there is no complex formation then
it will give linear relationship.

26. pH Titration Method
This is a method used in which the Complexation is achieve by
change in pH.
Eg. chelation of cupric ion by glycine...

As the two proton are formed in the reaction of equation the
addition of glycine to a solution containing cupric ion should
result in a decrease in pH .

27. Distribution Method
The method of distributing a solute, between two immiscible
solvent can be used to determine the stability constant for
certain compound..
Distribution Law= K= C1 / C2

28. Solubility Method
Higuchi & Lach used this method for detection of complex.
Take a container with closure system. Add drug in to the
container along with the solution of complexing agent.
In this p-amino benzoic acid(PABA) is drug & caffeine is
complexing agent.
The results of above experiments is plotted as molar conc.of
PABA Vs. molar conc. of caffeine.

29. Solubility Method
Higuchi & Lach used this method for detection of complex.
Take a container with closure system. Add drug in to the
container along with the solution of complexing agent.
In this p-amino benzoic acid(PABA) is drug & caffeine is
complexing agent.
The results of above experiments is plotted as molar conc.of
PABA Vs. molar conc. of caffeine.

30. Spectroscopy & Charge Transfer Complexation

A charge-transfer complex (CT complex) or electron-donor-acceptor
complex is an association of two or more molecules.
The resulting electrostatic attraction provides a stabilizing force
for the molecular complex.
The source molecule from which the charge is transferred is called
the electron donor and the receiving species is called the electron
acceptor.
Iodine + CCl4 = 520 nm
Iodine + Benzene =300 nm

31. Miscellaneous Method

IR
NMR
Polarography
X-ray Diffraction
Electron Diffraction

32. Protein Binding

Plasma protein binding refers to the degree to which medications attach to
Proteins within the blood.
A drug's efficiency may be affected by the degree to which it binds.
The less bound a drug is, the more efficiently it can traverse cell membranes or
diffuse.
Common blood proteins that drugs bind to are
1.Human Serum Albumin
3. Lipoprotein
4. Globulin
2. Glycoprotein

33. 1.Human Serum Albumin Binding

34. 2. Glycoprotein



3. Lipoprotein

35. 4. Globulin

36. Binding of Drugs with Blood Cells

37. Significance Of Protein Binding

1.Absorption
3. Metabolism
4. Elimination
2. Distribution
5. Drug Action
6. In Diagnosis

38. Factor affecting on Protein Binding

1.Factor relating to the drug
b. Concentration of drug
c. Affinity of drug for binding component
a. Physicochemical properties of drug
2. Factor relating to the protein
c. No. of binding sites
a. Physicochemical properties of Protein
b. Concentration of Protein

39. Factor affecting on Protein Binding

3.Drug interactions
b. Competition between drug & normal body constituents
c. Allosteric changes in protein molecules
a. Displacement reaction
4. Factor relating to the patient
a. Age
b. Disease state

40. Kinetics of Protein Bindings

41. Kinetics of Protein Bindings

42. Kinetics of Protein Bindings

43. Any questions?
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