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Exploring Muscle Function: PNP Hydrolysis and ATP's Role, Study notes of Biology
The role of protein function in biological diversity and the use of atp as a molecular motor in muscle systems. Through the analysis of pnp hydrolysis, a model reaction similar to atp hydrolysis, we gain insights into the relevant bond changes and the concept of kinetic stability. The document also provides suggestions for textbook reading and homework exercises.
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2010/2011
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B110 Lecture 1 Summary Fall 2010
Find the most relevant textbook pages or figures in brackets [ ]
I. An understanding of protein [chpt. 3] function is critical in
explaining biological diversity, e.g. why skeletal muscle of some
animals are “stronger” or “faster” than others.
A. An experimental system can be used to demonstrate that
muscle [ fig. 46.17] uses a transduction device (molecular motor) to
convert some of the potential energy [ 27] of ATP to do
mechanical work
- System: isolated gastrocnemius muscle of a frog-- ~ 3 cm long
& 1 cm wide
- Environment: water @ 25
o
C + “salts”{we will not discuss yet
why “salts” are needed}
{ Note that it is important to define the relevant features of the
experimental system & environment
B110 Lecture 1 Summary (cont.)
IB. ALL experimental systems are designed to study change from
state 1, time = 0 to state 2, time = 0 + X
- e.g., When enough KCl is added to the environment of the muscle
system@ time = zero, the muscle length decreases ~ 30% ( from 3 to
2.1 cm length) in ~ 50 msec (state 2, time = 0 + 50 msec) {we will
not discuss yet how KCl causes this}
- e.g., When a mass is attached to the end of the muscle, a maximal
mass X is moved ~ 0.9cm
against the force of gravity -- by definition the experimental system
has done mechanical work.
PNP
PNP
CCCCCCONOO
POOO
What are the relevant
bond changes in
PNP hydrolysis?
What are the relevant
bond changes in
PNP hydrolysis?
C O P O
O
O
simpler model of PNP
C O P O
O
O PNP with Lewis bond model depicting
valence “bonding” electrons only for
C-O bond
PNP
PNP
What are the relevant bond changes in PNP hydrolysis?
C O P O
O
O
proton
proton
O
H
H
hydroxyl
ion
hydroxyl
ion
O
H
H
H 2 O
H 2 O
C O P O
O
O
O
H
H
A collision produces the
transition state
C O H O P O
O
O
PN H
PN
Pi
Pi
“ reactant ”
“ reactants ”
Some suggestions on how to get the most out
of textbook reading
Some suggestions on how to get the most out
of textbook reading
B110 Lecture 1 Summary Fall 2010
Find the most relevant textbook pages or figures in brackets [ ]
I. An understanding of protein [chpt. 3] function is critical in
explaining biological diversity, e.g. why skeletal muscle of some
animals are “stronger” or “faster” than others.
A. An experimental system can be used to demonstrate that
muscle [ fig. 46.17] uses a transduction device (molecular motor) to
convert some of the potential energy [ 27] of ATP to do
mechanical work
The author reminds you to use the “energy” concept in it
most narrow ( and useful sense) --please do so in BIO 110
The author reminds you to use the “energy” concept in it
most narrow ( and useful sense) --please do so in BIO 110
Text pg. 27
Text pg. 27
as kinetic energy (KE) = 1/2 mv
2
Reading
a textbook
Reading
a textbook
gastrocnemius muscle cell
system : state 1 time = 0
x
g
system : state 2
time = 0 + ~ 50 msec
0.9 cm
0.9 cm
x
g
myofibril
myofibril
After the experiment was done, you can now say the
myofibril state 1 system had “potential energy”
NOTE:
myofibril state 2 system
has less or even zero
“potential energy”
NOTE:
myofibril state 2 system
has less or even zero
“potential energy”
You can claim a system has “potential energy” only if you are
reasonably certain that work can be done by the system...
You can claim a system has “potential energy” only if you are
reasonably certain that work can be done by the system...
... or you are reasonably certain that the temperature of the state 2
environment will increase ( heat is “supplied, “released”, “generated”)
... or you are reasonably certain that the temperature of the state 2
environment will increase ( heat is “supplied, “released”, “generated”)
Let examine the potential energy of a “chemical” system
PNP + H 2 O PN + Pi
a “chemical system”
Keq >> 1
K eq
1
K eq << 1
K eq << 1
Would the temperature
of the environment
change with time?
Would the temperature
of the environment
change with time?
“perfect”
insulator
“perfect”
insulator
100% PNP
0 PN or Pi
state 1, time = 0
environment
environment
system
system
H 2 O @ 25
o
C
What if I gave BIO 110 students
tubes of PNP in water that
were perfectly insulated to
prevent heat loss?
Energy can be defined as the capacity of a system to
do work as it changes from state 1 to state 2. IF work
was done and/or the environmental temperature
increased the state 1 system had potential energy
Text pg. 27
Text pg. 27
More useful “verbal” definition of “energy”
More useful as it is easy to measure work done
and heat generated and report it in joules
More useful as it is easy to measure work done
and heat generated and report it in joules
B110 Lecture 1 Summary (cont.)
Preview of lecture 2 --> 3 :
I. Claim : Myosin proteins within muscle cells are the energy
transduction devices ( molecular motors) that produce the force
needed to do mechanical work
A. Testable Model : Myosin protein acts as an enzyme to reduce the
kinetic stability of ATP as an early step in the force generating
mechanism
net Work (J) of frog muscle system = force ( n) x displacement (m)
net Work (J) of frog muscle system = force ( n) x displacement (m)
Measured maximal force generated by a frog gastrocnemius muscle ~ 0.5 n
Measured maximal force generated by a frog gastrocnemius muscle ~ 0.5 n
gastrocnemius muscle
system : state 1 time = 0
v
kg
system : state 2
time = 0 + ~ 50 msec
1.0 cm
1.0 cm
v
kg
frog
gastrocnemius
muscle
frog
gastrocnemius
muscle
net Work (J) = (0.5 n) x ( 0.01 m) = 0.005 J
net Work (J) = (0.5 n) x ( 0.01 m) = 0.005 J
What is the maximum theoretical mass ( X )
the muscle can lift against gravity?
What is the maximum theoretical mass ( X )
the muscle can lift against gravity?
1.0 cm
1.0 cm
v
kg
What is the maximum theoretical mass ( v )
the muscle can lift against gravity?
What is the maximum theoretical mass ( v )
the muscle can lift against gravity?
measured Work (J) of frog muscle system
= 0.5 ( n) x 0.01 (m) = 0.005 J
measured Work (J) of frog muscle system
= 0.5 ( n) x 0.01 (m) = 0.005 J
Work (J) = mass (kg) x acceleration (m/s
2 ) x displacement (m)
0.005 J frog muscle Work = ( v mass in kg) x ( 10 m/s
2 ) x 0.01 (m)
acceleration displacement
0.005 J frog muscle Work = ( v mass in kg) x ( 0.1)
0.005 J frog muscle Work = v mass in kg
= 0.05 kg ( 50 g)
= 0.05 kg ( 50 g)