2. INTRODUCTION
Protamines are small , arginine – rich nuclear proteins
that replace histones in the later haploid phase of
spermatogenesis
They are essential for sperm head condensation and
DNA stabilization
PRM – 1 and PRM – 2 are available as examples
Salmine in salmon fishes, clupeine in herring sperm and
iridine in rainbow trout are other examples
3. HISTORY
Protamine was originally isolated from the sperm of
salmon
Nowadays, it is produced through recombinant
technology
PROTAMINE SULPHATE:
It is a medication used to reverse the effects of heparin
Specifically, it is given for heparin overdose and is
given as injection into the vein
4.
5.
6. PROTAMINE STRUCTURE
The primary structure consists of P1 used for packing DNA in
sperm cells
It has 3 domains – arginine rich domain which plays a very
important role
After translation P1 is phosphorylated. Another phosphorylation
occurs when the sperm enters the egg
P1 binds to DNA and cysteine from the amino terminal of one P1
forms disulphide bond with the cysteine from the carboxy
terminal of another P1
The disulphide bond prevents the dissociation of P1 from DNA
until the bonds are reduced when the sperm enters the egg
The secondary and tertiary structures of protamines are not
known with certainity
7. PROTAMINES IN SPERMATOGENESIS
Protamine binds to the phosphate backbone of DNA, urgently
binding with the arginine – rich domain as an anchor
DNA is then folded into a toroid structure
A sperm contains 50000 toroids in its nucleus and each toroid
weighs 50Kb
Histones are removed from the DNA by transition nuclear
proteins so that protamines condense it
The ratio of protamine 2 to protamine 1 and transition nuclear
proteins has been found to change the sperm head shape
8. DOSAGE - Dosage for heparin reversal is 1.0 to
1.5 mg.
Protamine sulphate IV for every 100 IU of active
heparin
9. MEDICAL USES
When mixed with insulin, protamines slows down the
onset and increase the duration of insulin action
Protamine sulphate is an antidote for heparin overdose
It is used in cardiac surgery, interventional radiology
It is used in gene therapy
It is used as a drug to prevent obesity
