Insulin is a peptide hormone having 2 chains i.e A-chain & B-chain.it is produced in the β cells of Islets of Langerhans which forms the endocrine part of the pancreas which is primarily an exocrine gland.Endocrine portion accounts for only 2% of the total mass of the pancreas.Within the Islets of Langerhans, βcells constitute 65-80% of all cells.Human insulin has a molecular wt. of about 5806 Da.
Insulin exists as a dimer molecule in acidic to neutral water solution with Zn++ and as a hexamer
in neutral solution including 2 Zn++.Major target use of insulin is in
Liver- promotes glycogenesis,protein & fatty acid synthesis,carbohydrate utilisation,inhibition of gluconeogenesis.
Muscle- promotes membrane permeability and glucose & fatty acid synthesis.
In insulin, 3 disulphide bonds are present,between
A6-A11
A7-B7
A20-B19 |
Composition of Insulin (A-chain) |
Amino Acids |
Hagfish |
Porcine |
Bovine |
Human |
|
Neutral |
12 |
15 |
16 |
15 |
|
Acidic |
06 |
06 |
05 |
06 |
|
Basic |
03 |
- |
- |
- |
|
Total |
21 |
21 |
21 |
21 |
|
|
|
|
|
|
|
Neutral |
|
|
|
|
|
Strongly Hydrophilic |
04 |
05 |
05 |
05 |
|
Weakly Hydrophilic |
07 |
09 |
03 |
04 |
|
Weakly Hydrophobic |
01 |
01 |
08 |
06 |
|
|
|
|
|
|
|
|
|
|
|
|
|
Composition of Insulin (B-chain) |
Amino Acids |
Hagfish |
Porcine |
Bovine |
Human |
|
Neutral |
23 |
22 |
22 |
22 |
|
Acidic |
03 |
04 |
04 |
04 |
|
Basic |
05 |
04 |
04 |
04 |
|
Total |
31 |
30 |
30 |
30 |
|
|
|
|
|
|
|
Neutral |
|
|
|
|
|
Strongly Hydrophilic |
10 |
11 |
10 |
10 |
|
Weakly Hydrophilic |
07 |
06 |
06 |
07 |
|
Weakly Hydrophobic |
06 |
05 |
06 |
05 |
|
|
|
|
|
|
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To know further about insulin formation click,here... |
for amino acids of sequence of some known specis,click-->chain-A chain-B |
Molecular wt. of Insulin (Da) |
Human -- 5808.42
Chimpanzee -- 5808.42
Rat , Mouse I -- 5808.47
Rat , Mouse II -- 5787.38
Dog -- 5778.39
Cat -- 5757.38
Common Monkey -- 5759.40
Pig -- 5778.39
Cattle -- 5734.34
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