LBIS Proinslin Mouse/Rat is a sandwich ELISA system for quantitative measurement of mouse/Rat proinslin. This is intended for research use only.

What is proinsulin?

The amino acid sequence of proinsulin produced in B-cells of pancreatic islet of Langerhans is shown in the following figure (in the case of rat).


This proinsulin is processed by an enzyme at the position where two basic amino acids (K, R) moieties are present side by side shown by black arrows, yielding insulin and C-peptide (connecting peptide). Most proinsulin was processed while it passes Golgi apparatus to secretory granules, however, some remains without processing and present in secretory granules, and secreted into the blood circulation with insulin. The biopotency of proinsulin is estimated to be about 5-10% of insulin.
When we measure insulin or C-peptide in the blood, in general, we also measure the amount proinsulin because the structure of proinsulin includes those of insulin and C-peptide, if we ignore the three-dimensional structure. So, when we measures insulin by immunological method, we call the assay value IRI ( immuno-ractive insulin ) , discriminating from the real insulin level. IRI includes both insulin and proinsulin levels which reacted with the antibody.


  • Measurement range Mouse/rat 0.156~10 pmol/mL(1.47~94.3 pg/mL)
  • Samples are Mouse/rat serum or Plasma
  • A minute quantity of sample is measurable (10 μL with a standard method of operating)
  • Measurable in a short period (5 hours)
  • All reagents are solution types and are ready to use
  • High measurement accuracy and reproducibility


Sample Substance Cross reaction(%)
Mouse Proinsulin 100
Rat Proinsulin 100
Human Proinsulin
  • Crossing rate:at concentration of 1060 pmol/mL
  • +:cross-reactive
  • -:less than detection sensitivity

Kit components

1) Antibody-coated plate (8 x 12) wells/plate 1 plate
2) Standard proinsulin (200 pmol/L) 100 μL
3) Buffer solution 60 mL
4) Biotinylated Anti proinsulin Antibody 100 μL
5) HRP-conjugated streptavidin 100 μL
6) TMB Solution 12 mL
7) Stop Solution 12 mL
8) Wash Solution (x 10) 100 mL
9) Plate Seal 4 seals

Assay procedure


* Guideline of washing volume: 300 μL/well
**Guideline of shaking: 600-1200 rpm for 10 seconds × 3 times


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