Lactate dehydrogenase (LDH) is a tetrameric enzyme that in vertebrates exists in five electrophoretically distinguishable forms known as isoenzymes. According to their different mobility to anode, they are denoted LDH1 (H4), LDH2 (H3M), LDH3 (H2M2), LDH4 (HM3), and LDH5 (M4). A buffer system of the pH values 8.6–8.8 is commonly used for the separation of these isoenzymes in mammals. In the case of bird LDHs, the observation of five fractions is very difficult under this condition as they usually produce a pattern of one diffuse zone. Isoelectric focusing technique (IEF) in the pH range of 3–9 enabled a good and clear resolution of all five bird LDHs. Using this technique, it was also possible to observe the pattern in some tissues of chicken embryo.
Part of the book: Electrophoresis