Download Biochemistry of muscle

Biochemistry of muscle
•40-45 % of
body mass
•only system
converting
chemical
energy into
mechanical
2 types
-skeletal
(striated)
-smooth
Structural
unit muscle fiber
(myocyte)
Contains
many nuclei
located along
the cell
Muscle
structure
Muscle
structure
Chemical composition of
skeletal muscles
Proteins of muscles
3 types:
•proteins of
sarcoplasma
•proteins of
miofibrils
•proteins of
stroma
Proteins of Sarcoplasma
•Miogen fraction
(enzymes of glycolysis
etc.)
•Albumins
•Globulins
•Myoglobin
(chromoprotein,
provides the red color
to muscles, responsible
for oxygen storage)
Proteins of Stroma
•collage
•keratin
•elastin
are constituents of
connective tissue of
vessel walls, nerves,
sarcolema.
Proteins of Miofibrils
•Myosin (56-60 %)
•Actin (20-25 %)
•Tropomyosin (10-15 %)
•Troponin complex (4-6 %)
Structure of filaments and myofibrils
Sarcoplasma of
striated muscle
fibers contains
myofibrils
oriented along
which are built
of 2 types
protein
filaments: thick
and thin
•Muscle contraction is carried out due to the
sliding of thick and thin filaments
•Chemical energy – ATP hydrolysis
•Contraction is regulated by Ca2+ concentration
Structure of Thick Filament
•Thick filaments consist of myosin molecules
•Myosin molecule built of 2 heavy (200000 Da)
and 4 light (16000-25000 Da) chains
•Heavy chains are coiled around each other and
form the “tail” of the molecule
•2 light chains form the globular head of the
molecule
•The head has ATP-ase properties
About 400 molecules of myosin are
combined in the thick filament