GOOD MRNING

GODO MRONING

GOOD MORNING

Proteins

Diversity of Proteins

HemoglobinHormonesEnzymesAntibodiesCollagen…………

If there is a job to be done in the molecular world of our cells, usually that job is done by a Protein

“ Proteins are the work horses of the cell”

Hence

How did the first protein originate?

Origin of Life

Iam the author of “History of Humanity”

Frederick BantingHugo TheorellEarl W SutherlandGerald M EdelmanRodney PorterRosalyn S YalowAlfred G Gilman Martin RodbellStanley PrusinerAaron CiechanoverAvram HershkoIrwin RoseWendell Meredith Stanley

Paul D BoyerJohn E WalkerAaron KlugJohn Warcup CornforthChristian B AnfinsenStanford MooreWilliam SteinMax Ferdinand PerutzJohn Cowdery KendrewFrederick SangerArne W K TiseliusJohn Howard Northrop

http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/pictures/nobel-chemistry-medal.html

What is Protein folding ?

Structural Levels of ProteinsPrimary Secondary

Protein stability

The extreme diversity in their chemical and physical properties is achieved due to the variety in their properties of their building blocks Effort to design a protein with a specific function, nature has to solve an extremely difficult problem It needs be active and thermodynamically stable

Protein stability The situation becomes more complicated since this stability must be ascertained in a certain range of environmental conditions

The native conformation of a protein is stable in a narrow range of temperature,pH, chemical composition of solvent, etc.

ProteinpH Temp.

Salt Conc.

• Hydrogen Bonding

• Vander Waals interactions

• Ionic strengths

• Disulfide bonds

Hydrophobicity: the dominant

force in protein folding

Forces involved in Protein stabilisation

Protein Denaturation

The activity of a protein depends on its three-dimensional structure.

Intramolecular bonds, especially hydrogen bonds, maintain the structure.

Hydrogen bonds may break when the pH drops or the temperature rises above normal denaturing the protein

Protein Denaturation with extreme pH or Temp.

Folding a protein on a computer with a full-atom

model in explicit solvent has been termed the

'holy grail' of the protein folding problem

Berendsen HJC:Science 1998, 282: 642)

A glimpse of the holy grail?

“The Quest for Holy Grail”

unfolding refolding

Anfinsen - Nobel Prize 1972

8M ureaDilution of denaturant

“ Ribonuclease ”

Break through…

Protein denaturation by temperature

R John Ellis Current Opinion in Structural Biology 2001, 11:114–119

Macromolecular crowding

Invitro refolding of a Protein

Native

UnfoldedProtein with 100 amino acid residues

Assume 2 conformations for each residue

2100 possibilities

1010 years of random searching

Levinthal paradox (1968)

Folding models:

Framework model Hydrophobic collapse mode Nucleation condensation model

Folding is a stepwise process

Local secondary structures forms first and this is Followed by longer range interactions

A stably folded proteins has…..

Hydrophobic side chains buried Charged side chains on the surface Cysteine’s form Covalent disulfide bonds

“All these features will contribute to Minimum” energy state

Pack as close together as possible Pack as close together as possible Minimize contacts between hydrophobic Minimize contacts between hydrophobic groups and watergroups and water

Free energy funnel

Native structure

Mutations Premature termination of Translation Fault in post-translational modifications Strong Promoters High Inducer concentrations

Reasons for protein misfolding

Loss of conformation due to stress`

ALL CELLS

ALL ORGANISMS

Living in the World

Must cope with…

Stress !!!

What is stress?

In biology, stress is the driving force behind the process of adaptation and evolution.

Driven by inner need and Stress

Interesting storyF. Ritossa –1960 discovered the heat shock (HS) response while observing the salivary cells of Drosophila and named them HSP’s

My name is Chaperone

Tempenviron

Tempcell

Folded Proteins

Unfolded Proteins Aggregates

Loss of ProteinFunction

Networkfailure

Death

Cell

How do Chaperones work? Heat shock proteins stabilize proteins and

are involved in the folding of denatured

proteins

Hsp 100

Hsp 90

Hsp 60

Hsp 70

SmallHsp’s

Hsp 40

Family Major Functions

Protein disaggregation, thermotolerance

Regulatory interactions with signaling proteins, stabilization of misfolded proteins

Protein folding, membrane transport of proteins

Protein folding (limited substrates in eukaryotic cytoplasm)

Protein folding, co-chaperone for Hsp70

Stabilization of misfolded proteins, thermotolerance,eye lens structural proteins

Functions of HSP families

Other inducers of the heat shock proteins:

Oxidizing agents

Metals

Sulfhydryl reagents

• Poisonous gases…………

The Nobel Prize Chemistry 2004

"Kiss of Death"

Aaron Ciechanover, Avram Hershko, Irwin Rose

Exit

Entry

Protein misfolding Diseases

Protein misfolding diseases can be classified in to two categories

Diseases caused due to the misfolding or degradation of misfolded proteins Diseases caused due to accumulation of misfolded proteins

Disease Protein Involved

Cystic Fibrosis CFTR

Retinitis pigmentosa Rhodopsin

Cancer p53

Osteogenesis imperfecta

Type 1 procollagen

Pro A

Marfan Syndrome Fibrillin

Sickle Cell anemia Hemoglobin

Disease caused due to the misfolding or degradation of misfolded Protein

Polymerized Sickle Hemoglobin

Sickle-cell anemia

Sickle shaped RBC

Retinitis Pigmentosa

Normal Vision

Retinitis Pigmentosa

Gene codes for a protein, CFTR, which is chloride ion channel. Small fraction of protein matures to the cell surface Mutation in protein CFTRΔF508 doesn't reach the cell surface.

Cystic fibrosis

Osteogenesis imperfecta

Disease Protein involved

Alzheimer’s Disease Amyloid - peptide

Huntington Disease Huntington protein

Spongiform encephalopathies

Prion Protein

Diseases caused due to the accumulation of misfolded protein

Prion infected Brain of a cattle

Bovine Spongiform Encephalopathy

Prion Protein

Prion diseases Human - Kuru & CJD

Sheep - Scrapie.

Cow - Mad Cow disease

KuruVictim

MadCow

“I Have Completely Forgotten Why I came Upstairs “

Alzheimer’s Disease

SummaryProper folding of proteins is essential for a cell to carry out Its normal cellular function

Misfolded proteins can result in a wide variety of pathological conditions

Existing therapies do not provide efficient cure for these Pathological conditions

Small molecules called chaperones that increase the stability of the native state offer innovative therapeutic solution

Why study protein folding?Understanding Protein folding in vivo helpsin adapting them in invitro and Insilco Molecular Drug design Protein-protein interactions Grastim Dengue vaccine

Mobile phones, heat shock proteins Mobile phones, heat shock proteins and cancerand cancer

Mobile phone use

Absorption of energy in to brain tissue

Protein unfolding

Heat shock response

Heat shock proteins induced HSP 27,40,70,90,110Repeated mobile use

Chronic expression of HSPs

Inductionof cancer

Increasedmetastasis

Inhibition of Apoptosis

Resistance to anti cancer drugs

Proteinrefoldin

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Thank you

Supplementary