SLIDE 1
P h y s i c s
- f
b i
- l
- g
i c a l s y s t e ms – P H 5 4 9
L E C T U R E 1 3 :
b i
- l
- g
i c a l p
- l
y me r s
mithun@phy.iitb.ac.in Office: Physics 303
P h y s i c s o f b i o l o g i c a l s y s t - - PowerPoint PPT Presentation
P h y s i c s o f b i o l o g i c a l s y s t - - PowerPoint PPT Presentation
P h y s i c s o f b i o l o g i c a l s y s t e ms P H 5 4 9 L E C T U R E 1 3 : b i o l o g i c a l p o l y me r s mithun@phy.iitb.ac.in Office: Physics 303 S I N G L E MO L E
SLIDE 2
SLIDE 3
F O R C E E X T E N S I O N : D N A
SLIDE 4
F O R C E E X T E N S I O N : R N A
https://commons.wikimedia.org/w/index.php?curid=815268 https://commons.wikimedia.org/w/index.php?curid=806690
Stem Loop Pseudoknot
SLIDE 5
F O R C E E X T E N S I O N : P r
- t
e i n
Titin: 244 folded domains, 1µm length
SLIDE 6
P r
- t
e i n s a s r a n d
- m
wa l k s
SLIDE 7
C O MP A C T r a n d
- m
wa l k s ⟨ R
2⟩ ∼ N 2/3
SLIDE 8
T H E P R O T E I N F O L D I N G P R O B L E M
SEQUENCE Structure Structure Function
How does a protein sequence correspond to a particular structure?
A random search in structure space is IMPOSSIBLE!
SLIDE 9
T H E H P Mo d e l f
- r
p r
- t
e i n s
SLIDE 10
A T
- y
mo d e l f
- r
a n H P p r
- t
e i n
Consider a 6-amino acid protein on a 3x2 lattice How many possible sequences can we have?
2
6 = 64
How many possible structures can we have?
3
SLIDE 11
A T
- y
mo d e l f
- r
a n H P p r
- t
e i n
Sequence: HPHPHP No UNIQUE ground state!
SLIDE 12
A T
- y
mo d e l f
- r
a n H P p r
- t
e i n
Sequence: PHPPHP UNIQUE ground state!
SLIDE 13
A T
- y
mo d e l f
- r
a n H P p r
- t
e i n
What is the probability of the native state?
pnative = e
−2βε
e
−2βε+2 e −4βε
SLIDE 14
D E S I g n s t r a t e g i e s f
- r
p r
- t
e i n s
HPPHHPPHPPHHPPH... Enzymatic activity