How H.Insulin is differ from Bovine & Porcine insulin

By : Vijit Agrawal

Proinsulin

• Proinsulin is the prohormone precursor to insulin made in the beta cells of the islets of Langerhans, specialized regions of the pancreas.

Chemical Differences

Species Immunogenicity

Human Least

Porcine Intermediate

Bovine Most

1

•Proinsulin is synthesized in the endoplasmic reticulum, where it is folded and its disulfide bonds are oxidized.

2

•It is then transported to the Golgi apparatus where it is packaged into secretory vesicles.

3

•Where it is processed by a series of proteases to form mature insulin.

The C-peptide is abstracted from the center of the proinsulin sequence; the two other ends (the B chain and A chain) remain connected by disulfide bonds

Clinical Differences

• Human insulin has a stronger initial hypoglycemic effect than either porcine or bovine insulin.

• Insulin ranking as high initial and a less delayed hypoglycemic effect is as follows..

Human > Porcine > Bovine

• All insulins except conventional bovine have neutral pH. Conventional bovine insulin was acidic.

• Differences in bioavailability between these three species of insulin are relatively small.

• Immunogenicity.

Differences based on their potency and bioavailability

• The hypoglycemic potency of porcine relative to bovine insulin was less than the relative bioavailability in these comparisons.

• When human is compared to porcine insulin, a higher hypoglycemic potency than relative bioavailability was observed, especially during first 180 min after injection.

• The comparison between human and bovine insulin also showed a higher hypoglycemic potency than the bioavailability with the earlier responses, and vice-versa with the later effects.

Importance of C-Peptide

• The connecting peptide, or C-peptide, is a short 31-amino-acid protein that connects insulin's A-chain to its B-chain in the proinsulin molecule.

• Proinsulin is converted to insulin and C-peptide in the pancreatic beta cells : latter two peptides are secreted in equimolar concentrations.

•  Measurements of serum C-peptide provide a means of assessing pancreatic beta cell function in addition to insulin. 

• The C-peptide assay has also been used to facilitate the diagnosis of various hypoglycemic conditions, including islet cell tumors (INSULINOMA).

• The extraction of C-peptide in the urine reflects average serum values over a period of time and urine C-peptide measurements are especially useful in children or individuals in whom repeated blood sampling is difficult.

• C-peptide levels are checked in women with Polycystic Ovarian Syndrome (PCOS) to determine degree of insulin resistance.