[PL] / [PL] + [P] OR Occupied binding sites / total binding sites OR [L] / Kd + [L]

Chapter 6 Flashcards by Taylor Nunes

Negative allosteric effector

2,3-BPG
H+
CO2

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Positive allosteric effector

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Lower Kd

Higher affinity

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Thick filaments

(myosin)
Bind ATP
Connected to Z disks via titin protein
Composed of myosin filaments

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Thin filaments

(Actin)
Bind calcium
Composed of actin monomers
Contain tropomyosin 
Composed of troponin complex

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TnC

Binds to Ca 2+ and controls muscle contraction

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TnI

Inhibits myosin binding to actin

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TnT

Binds to tropomyosin

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Ca2+ initially binds to

Troponin

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Calciums role in muscle contraction

Ca2+ binds to troponin which induces a conformational chance on the actin filaments that exposes myosin binding sites on actin sub units

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muscle contraction shortens the distance between:

Z-disk proteins

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Z-disks contain the following proteins:

Vimentin
α-actinin
Desmin

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Ѳ =

[PL] / [PL] + [P]

Occupied binding sites / total binding sites

[L] / Kd + [L]

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Kd =

[P] [L] / [PL]

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To find Kd by looking at a graph

Find fractional saturation 0.5 on Y-axis and locate Kd on X-axis

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Oxygen Binding Curves for Myoglobin

and Hemoglobin

Myoglobin = Hyperbolic

Hemoglobin= Sigmoidal

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Ligand binding is a ______ process

involving ______ interactions

reversible

noncovalent

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P 50 =

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______ is more effective at transporting Oxygen than ______

Hemoglobin

Myoglobin

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As pH incresaes

Affinity for binding oxygen increase

Explains why pH is higher in lungs where O2 must bind

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Equation for dissolving of CO2

CO2 + H2O HCO3- + H+

With help of enzyme carbonic anhydrase

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As [CO2] increases

[H+] also increases, and affininty for binding O2 goes down

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in tissue —–> pH is ________ because of ________

—–> ________

Low in blood
Accumulation of CO2
O2 is released by hemoglobin

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In lungs ——> pH is ______ because _______ is being _____ ——> ___________

Higher
CO2, Exhaled
O2 is bound to HG

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2,3-BPG

Traps HG is the T state | Aids in the binding of HG

2,3-BPG bindig to HG

2,3-BPG has a -5 charge which binds tot he +8 charger in the central canal

In lungs 2,3-BPG is

mostly unbound

In tissue 2,3-BPG is mostly

Bound, stabilizing T- state

BPG also plays an important role in adaptation to:

higher altitudes

When O2 binds central canal ________ and ________ is released

Narrows | 2,3-BPG

[O2] is much ______ at high altitudes. | Therefore ________ is produced in larger amounts

lower 2,3-BPG

The O2 binding curve at high altitudes:

85% sat in lungs 45% sat in tissues 40% release of O2

The O2 binding curve at high altitudes if 2,3-BPG was not produced:

90% sat in lungs 57% sat in tissues 33% release of O2

Arterial bood flow

Lungs to tissue

Venous blood flow

Tissue to lungs

Anemia is due to a mutation in

α or β hemoglobin | subunits

Anemia is characterized by

Reduced oxygen transport efficiency from the | lungs to the tissue caused by altered hemoglobin function or reduced number of red blood cells

SIckle cell disease

Beta subunit mutation in Hemoglobin S

Sickle cell genotype

Glu6 (A3) ---> Val6

Sickle cell phenotype

Globin protein aggregation

In sickle-cell hemoglobin Glu6 in the β chain is | mutated to Val, thereby creating:

a hydrophobic patch on the surface of the molecule

Effect of sickle-shaped cells

clog small blood vessels, causing pain and life threatening crises.

This patch happens to ______ a hydrophobic pocket in the _________ of another hemoglobin molecule.

fit and bind | deoxygenated form

When hemoglobin in the blood capillaries delivers its | oxygen:

the hydrophobic interactions can occur and the highly concentrated hemoglobin in the cells polymerizes into fibers

Together, actin and myosin make up more | than ____ of the protein mass of muscle.

80%

muscle fibers

large single multinucleated cell | composed of many myofibrils

Muscle fiber AKA

Myoblast

Myofibril

Composed of actin myosin | Contains many sarcomeres

Bundle of muscle fibers

Fascicle

During muscle contraction The length of ________ decreases. The length of _________ remain constant

sacromere | thick and thin filaments

Model by which muscle contraction occurs

Sliding Filament Model sliding of the thick and thin filaments past each other so that the Z disks in neighboring I bands approach each other

Myosin length

1600 angstroms

Actin and tropomyosin bind with

troponin

Tropomyosin

A second thin filament protein Tightly associated with actin

G actin

Globular Monomeric sub units that make up f actin

F actin

The thin filament actin Filamentous assemblage of G-actin monomers

Each _________ can bind a | single myosin head.

G actin

The _________ regulates muscle contraction by controlling the access of ________ to their binding sites on actin.

tropomyosin-troponin complex the myosin heads

Titin protein functions as ______, which connects ______ filaments to _______

a spring myosin Zdisk proteins

Tropomodulin

an actin filament capping protein

ELC and RLC

Essential light chains | Regulatory light chain

____ and _____ required for muscle contraction

Ca2+ | ATP

I band contains

thin filaments | 70 angstrom diameter

A band contains

thick filaments | 150 angstrom diameter

Myosin is made up of ________

6 polypeptide chains | 2 heavy and 4 light chains

______ is converted to ______

Chemical energy | Motion

e- density in A band vs I band

A - Higher | I - Lower

e- density in H zone vs M disk

M disk - higher | H zone- lower

two areas that compact during contraction

H zone | I band

When Ѳ is 0.5

Kd = [L]

Troponin complex consists of:

TnC TnI TnT

Longest known protein in nature

Titin