C-Peptide ELISA Kit (Connecting Peptide)

INTENDED USE

Human c-peptide ELISA kit is a reliable quantitative procedure for measuring connecting peptide (c-peptide) in human serum, plasma and urine. This assay has a minimum sensitivity limit of 0.064 ng/ml.

BACKGROUND

C-peptide is short for connecting peptide, it is responsible for joining the A and B chains of insulin within the proinsulin molecule. The enzymatic cleavage of proinsulin results in the release of insulin into circulation and c-peptide (a 3000 MW residual fragment) being formed. It have no metabolic function and tend to be 31 amino acid peptide residues that have a half-life in circulation that can be between 2-5 times longer when compared to insulin.

One of the main reasons why it is of great interest from scientist is because both insulin and c-peptide are secreted in equimolar amounts. Therefore by measure c-peptide levels permits the quantitation of insulin secretion. There are many advantages it offers over measuring insulin such as serum and urinary samples can be measured, displays relative metabolic inertness, between two to five times longer half-life, 5-6 times greater levels in peripheral venous blood and its ability to distinguish endogenous from injected insulin.

The measurement of c-peptide levels is in fact better in many ways to determine the concentration of endogenous secreted insulin rather than measuring peripheral insulin levels itself. Coupled with the fact that there are many highly sensitive assays that are available and these will allow the measurement of extremely low concentration possible.

CONTENT

All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

• Microtiterwells: Wells coated with mouse anti-human c-peptide antigen.
  
• Standard 0-5: Lyophilized, concentrations: 0, 0.2, 0.7, 2.0, 6.0, 16 ng/mL. The standards are calibrated against WHO approved Reference material IRR, code 84/510.
  
• Sample Diluent.
  
• Antiserum: Monoclonal mouse antibody.
  
• HRP Enzyme Complex.
  
• Enzyme Conjugate.
  
• TMB Substrate Solution.
  
• Stop Solution: Contains 0.5 M H2SO4. Avoid contact with the stop solution. It may cause skin irritations and burns.
  
• Wash Solution (40x Concentrated).

SENSITIVITY

The minimum sensitivity detection limit of human connecting peptide (c-peptide) using current c-peptide ELISA kit was approximately 0.064 ng/ml. The dynamic range for this assay is 0.2 – 16.0 ng/ml.

ASSAY CHARACTERISTICS

– Expected Normal Values: Serum (Post 12-hour fasting)(0.5 – 3.2 ng/mL), Urine (1 – 200 µg/day).
– Assay Dynamic Range: 0.06 – 16 ng/mL
– Sensitivity: 0.064 ng/mL.
– Specificity (Cross Reactivity): The cross-reactivity of intact or split-Proinsulin is clinically not significant.
– Intra Assay Variability: 5.13 – 6.70%
– Inter Assay Variability: 8.38 – 9.92%
– Recovery: 88.1 – 104.8% (Serum), 96.2 – 109.2% (Urine).
– Linearity: 97.1 – 110.6% (Serum), 92.4 – 103.6% (Urine).
– Interfering Substances: None
– Drug Interference: None
– High Dose Hook Effect: None

REFERENCES

1. Evidence for inhibitory autocrine effects of proinsulin C-peptide on pancreatic β-cell function and insulin secretion. Diabetes Obes Metab. (2014) 16 (10): 937-46. McKillop A.M., et al.
2. C-peptide: new findings and therapeutic possibilities. Diabetes Res Clin Pract. (2015) 107 (3): 309-19. Review. Wahren J. and Larsson C.
3. C-peptide replacement therapy as an emerging strategy for preventing diabetic vasculopathy. Cardiovasc Res. (2014) 104 (2): 234-44. Review. Bhatt M.P., Lim Y.C. and Ha K.S.

ADDITIONAL INFORMATION

• Full Name: C-Peptide ELISA Kit (Connecting Peptide)
• Reactivity: Human
• Sample Type: Serum, Plasma, Urine
• Sensitivity: 0.064 ng/ml

OTHER RELATED ELISA KITS

• Proinsulin ELISA Kit
• Insulin ELISA Kit
• IGF-I ELISA Kit