9th Iran Biophysical Chemistry Conference, 24-25

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Feb 25, 2010 - 9th Iran Biophysical Chemistry Conference, 24-25 February 2010, Tarbiat Modares University, Tehran, Iran. S32 were investigated using ...
9th Iran Biophysical Chemistry Conference, 24-25 February 2010, Tarbiat Modares University, Tehran, Iran

were investigated using spectrophotometry ABTS-based method (reduction

of

the

cation

ethylenebenzothiazoline-6-sulfonic

radical

of

acid)).The

2,20-azinobis(3-

results

indicate

the

1- Department of Biology, College of Sciences, Shiraz University, 71454, Shiraz, Iran, 2- Biopolymères Interactions Assemblages, INRA, équipe Fonctions et Interactions des Protéines Laitières, B.P. 71627,

overall antioxidant activity of camel caseins and their hydrolysis were

44316 Nantes Cedex 3, France, 3- Institute of Biochemistry and

higher than bovine caseins and peptide fraction between 5-10 kDa

Biophysics (IBB), University of Tehran, Tehran, Iran.

showed the highest antioxidant activity. It can be concluded that camel caseins or their hydrolysates can be used as a novel ingredient for

Beta-CN (ǃ-CN) molecule is a single chain protein of known sequence

producing nutraceuticals and natural drugs with high antioxidant

containing a cluster of five phosphoseryl residues in the N-terminal

activity.

hydrophilic domain. This protein is one of the highly allergenic components of cow's milk which possesses multiple sequential

Key words: antioxidant peptides, free-radicals, Camel Casin, kinetic

antigenic determinants (epitopes) in its primary structure. Moreover ǃ-

parameters.

CN is member of intrinsically unstructured protein (IUP) family

Abstract No.72

and purified from E. coli, ǃ-CN lacks the phosphoryl residues, because

exhibiting chaperone-like activity in vitro. In this study as expressed the prokaryotic host does not realize post-translational phosphorylation The biophysical chemistry interaction of silver nanoparticles

of the eukaryotic protein (ǃ-CN). Subsequently, the impact of

and doxorubicin

phosphoryl residues on IgE mediated immune reactivity (allergenicity) and chaperoning function were investigated and compared using the

Azadeh Hekmat1, Ali Akbar Saboury1 and Adeleh Divsalar1,2 1- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran, 2- Department of Biological Sciences, Tarbiat Moallem University, Tehran, Iran

beings, occurs when abnormal cells grow out of control in one or both breasts. Anthracyclines, particularly doxorubicin (DOX) are widely used antibiotics for medical treatments of breast cancer. In this research, we have studied the interaction between silver nanoparticles and drug

of

doxorubicin

using

UV-visible

enzyme-linked immunosorbant assay (ELISA) were performed in order to compare chaperoning abilities and allergenicity of the beta-caseins respectively. The results exhibit major roles played by the cluster of phosphoseryl residues in both chaperoning activity and in shaping of

Breast cancer, which affects an important percentage of human

anticancer

recombinant and native ǃ-CNs. Spectroscopic measurement and

spectroscopy,

fluorescence spectroscopy and circular dichruism (CD) at 37 ˚C. We have determined the binding constant (Ka=215.34 mM-1) and

the allergenicity profile of ǃ-CN. Consequently this study suggests the major phosphorylation site as one of the important antigenic determinant elements along the primary structure of beta-casein. Moreover phosphoseryl cluster plays significant role in amphipathic character and subsequently chaperoning function of this molecule. Key

words:

Beta-casein,

Chaperone-like

activity,

Allergenicity,

Phosphoseryl cluster.

enthalpies of this interaction. The interaction of doxorubicin with varying silver nanoparticle concentration represented one binding sites. Altogether, our data indicated that there is a strong interaction between silver nanoparticles and DOX. Key

words:

Doxorubicin,

Silver

Abstract No.74 Molecular dynamics study of transition conformation in

nanoparticles,

Thermodynamic

Human serum albumin denaturation

parameters.

Farideh Zergani 1, Mohammad-Reza Dayer2 and Omid Ghayour3

Abstract No.73

1- Department of Chemistry, Science and Research Branch of Islamic Azad University of Ahvaz, 2- Department of Biology, Faculty of

Impact of the Major Phosphorylation Site on Chaperoning Function and Allergenicity of Beta-Casein

Science, Shahid Chamran University, 3- Department of D3, Yapna TeX, Yekta Pouya Company

Reza Yousefi*1, Hojjat Khalili-Hezarjaribi1, Zohreh Tavaf Langeroudi1,

Human serum albumin (HSA) is most abundant protein in human blood

Hajar Zamani1, Thomas Haertle2, Ali-Akbar Moosavi-Movahedi3

plasma, is produced in the liver and comprises about half of the blood serum protein. HSA is soluble in serum and is important in regulating

S32

Journal of the Iranian Chemical Society, Vol. 7, Suppl. 1, February 2010

blood osmotic pressure. HSA serves as carriers for molecules with low

Molecular chaperones form a family of proteins believed to evolve

water solubility, including hydrophobic hormones, unconjugated

towards prevention of protein unfolding and aggregation in denaturing

bilirubin, free fatty acids, calcium ions, and some exogenous chemicals

conditions. Consequently, chaperones play important role in preventing

such as drugs. In the present work, we used molecular dynamics

of the serious problems so called aggregation diseases such as

simulation methods to study the structural alterations and nature of

Alzheimer’s, Parkinson’s, and Huntington’s, Creutzfeldt - Jakob disease,

forces involved in the transition from native to denatured states of

cataract and type II diabetes. In this study the ability of bovine beta-

HSA. Gromacs version 3.3.3. package installed over UBUNTU Linux

casein to prevent aggregation of pancreatic insulin was considered as a

version 8.10 (Intrepid) on a Intel ® Pentium ® M based PC at 1.6

sign of its chaperone-like activity. The chemical-induced aggregation of

GHz with 469.5 MiB of Ram package, and ffgmx force field was

insulin was detected by measuring of the increase in optical density at

used in the present work. The coordinates used for HSA was

360 nm as a function of time. For quantitative estimation of

obtained from RCSB Protein Data Bank, with PDB ID: 3CX9. The

chaperone-like activity of beta-casein, k1 and Alim were derived from

protein was equilibrated in a cubic box with 9.581nm x 5.959nm x

the aggregation curves, with the assumption that, as proposed

9.717nm dimensions. Energy minimization was carried out using

already, aggregation follows completely first order kinetics. Alim is the

steep integrator and Fmax were chosen 1000 for 1000 step.

limiting value of absorbance (A) at tĺ ’ and k1 is the rate constant of

Molecular dynamics with all-bond constrain for 200ps and finally

the first order reaction. The k1.Alim product is the initial rate of

no constrain were used to simulate done for up to 4ns. Our results

aggregation and it is expressed in unit of absorbency per time unit. To

show heating up the albumin solution exerts vast alterations in the

quantify chaperone-like activity of beta-casein at different molar ratios

system leading to denaturation of albumin. Stepwise refinement of

of chaperone/target protein, k1.Alim of each experiment was divided

simulation trajectories revel cooperative events during denaturation.

individually per (k1.Alim)0 of the control experiment (absence of beta-

Increase in kinetic energy at 52qC leads to decrease in solvent-protein

casein) and subtracted from unit. The resulting values varied from zero

H. Bond cause a simultaneous increase in protein-protein H. Bond.

(in the absence of casein chaperone) to one (where k1.Alim= 0). These

However obvious decrease in gyration radius and in solvent accessible

values,

surface area (SAS) proves the formation of a more compacted

chaperone/substrate ratio, are correlated directly with the chaperone-

conformation in albumin before denaturation takes place. More

like activities of beta-casein chaperone. The percentage of chaperone-

increasing in temperature causing H. Bond breakdown, converting

like activities can be obtained by multiplying the obtained values by

regular structures to random ones, and finally leading to completely

100. Advantage of the current approach is to apply combination of key

denatured structures, in about 70qC (Tm). We also studied the position

parameters (k1 and Alim) in measuring of chaperone-like activity.

increasing

from

0

to

1

with

the

increase

of

the

changing of Tryptophan-212 during the simulation. Trp(212) is known to lie in the hydrophobic pocket of HSA and is located on the surface of

Key words: Chaperone-like activity, Quantification, First order rate

sub domain 4 in domain II. Outgoing of Trp(212) at the melting

constant (k1), Limiting value of absorbance (Alim).

temperature is in accordance with denatured conformation. Key words: Molecular dynamics, HSA, gyration radius, hydrophobic

Abstract No.76

pocket, denaturation. The Importance of a Flexible Loop in Kinetic Pathway of Refolding of Iranian Firefly Luciferase Abstract No.75

and Its Thermodynamic Stability

A Novel Approach to Quantify the Chaperone-Like activity 1

1*

Khosrow Khalifeh, Bijan Ranjbar*, Bagher Said Alipour, Saman Hosseinkhani*

1

Reza Yousefi , Hajar Zamani , Zohreh Tavaf Langeroudi , Marziyeh Valifard1, Hojjat Khalili- Hezarjaribi1, Thomas Haertle2, Ali-Akbar Moosavi-Movahedi3

Department of Biophysics & Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box, 14115–175 Tehran,

1- Department of Biology, College of Sciences, Shiraz University,

Iran, E-mail: [email protected], [email protected]

71454, Shiraz, Iran, 2- Biopolymères Interactions Assemblages, INRA, équipe Fonctions et Interactions des Protéines Laitières, B.P. 71627,

In order to elucidate the effect of a flexible ǃ-strands connecting loop

44316 Nantes Cedex 3, France, 3- Institute of Biochemistry and

on the stability of folded state and kinetic pathway of refolding of

Biophysics (IBB), University of Tehran, Tehran, Iran.

Iranian

firefly

luciferase

(Lampyris

turkestanicus), kinetics and

S33