The Microgel/Interlab G26 H.R. Proteins Electrophoresis method provides a new level of total automation on agarose gel combined with an enhanced sensitivity thanks to its highly sensitive staining solution.
The new Microgel High Resolution kit is intended for the multifractionation of proteins in different types of human fluids such as neat or concentrated urines, cerebrospinal fluid (CSF), and diluted serum. You simply pipette the specimens into the sample well, put the gels in the holders, start the instrument and walk away!
- Urine is formed by ultrafiltration of plasma across the glomerular capillary wall that has a sieving effect on larger plasma proteins into the ultrafiltrate.
The passage of plasma proteins across the glomerular barrier is a function of molecular size, electrical charge and molecular configuration.
- All the molecules greater than 50,000 daltons are retained by the glomerular barrier.
Albumin and transferrin with a molecular weight of respectively 65,000 and 80,000 daltons are almost completely retained, only about 0.1 % of each ultrafiltrates.
All the plasma proteins with a molecular mass under 50,000 daltons pass through the glomerular wall, but all are reabsorbed by the proximal tubule cells, and are degraded by enzymes in to amino acids which are returned to the blood. The final filtrate usually contains some traces of albumin and transferrin (under 0.1% of the total proteinemia). Proteins normally present in urine are albumin and transferrin in low quantity. The physiological proteinuria is about 150 mg / 24 hours.
Electrophoresis of urine is the best way to detect abnormal proteins in urines.
The presence of an abnormal band (for example a band in the position of the transferrin) requires a complementary identification (Bence-Jones immunofixation).
The presence of proteins in the a1 and a2 zones, requires complementary investigation (micro-proteins etc). Abnormal proteins in urine can be present even with a normal level of proteinuria.
It is recommended to analyze fresh urine as soon as possible because some proteins are denaturated in alkaline urine and some others in acid urine (for example, b2 microglobulin is denaturated at a pH under 5.5, while Retinol Binding Protein (RBP) is denaturated at alkaline pH).