The effect of dilution and substrate repletion on the LDH isoenzyme distribution of sera with high LDH activities

Lactate dehydrogenase isoenzymes

The analytical procedures for LD isoenzymes include electrophoresis, chromatography, immunochemical and kinetic methods. Electrophoretic methods are generally preferred because the resulting patterns are directly observable and all five isoenzymes are resolved in a single procedure. Chromatographic methods, with the introduction of HPLC, have recently been perfected in terms of speed, resolution, precision and accuracy. Immunochemical methods and kinetic methods are attractive because of their speed and simplicity. Therefore, the latter methods are used mainly for assaying acute myocardial infarction, where generally the determination of LD-1 and LD-2 is sufficient. In all other instances, however, electrophoretic separation is currently preferred. Ion-exchange high-performance procedures are useful prospects, particularly in view of their velocity in comparison with electrophoresis. In general, the LD isoenzymes assay contributes considerably to diagnosis, but the results must be used with an adequate knowledge of biochemistry, physiology and the advantages and drawbacks of the different assay methods used.

A rapid and simple procedure for the preparation of human lactate dehydrogenase-2 from erythrocytes using an ion-exchange mini-column

We describe a simple ion-exchange chromatography technique for the rapid preparation of lactate dehydrogenase-2 from lysed human erythrocytes obtained either from plasma or serum clots. The procedure appears capable of scale-up to larger columns thus making it ideal as an initial step in a more extensive purification scheme.

Unusual increases in serum lactate dehydrogenase isoenzyme-5 activity caused by severe congestive cardiac failure: two case reports

Two cases of congestive cardiac failure had unusually high activities of serum lactate dehydrogenase and lactate dehydrogenase isoenzyme-5. Values for isoenzyme-5 exceeding 87% of the total serum activity, and increases of 228- to 380-fold of the upper reference limit, are very uncommon.

An artefact in lactate dehydrogenase isoenzyme patterns, assayed by fluorescence, occurring in the serum of patients with end-stage renal disease requiring maintenance haemodialysis

In patients with end-stage renal disease requiring maintenance haemodialysis we have observed that serum albumin becomes fluorescent (excitation 356 nm, emission above 405 nm). This fluorescence is detected in the fluorescent assay of lactate dehydrogenase (LDH) isoenzymes on thin-layer agarose creating the impression of an additional LDH isoenzyme anodal to LDH1. This artefact disappears, or is much reduced, following successful donor kidney transplantation. It is not seen in any other pathological condition. This phenomenon can readily be detected by means of "blank" assays on the agarose plates after specimen application and after electrophoresis of the specimen without the substrate overlay.

A simple and rapid procedure for the preparation of human LDH-1 and LDH-5 using an ion-exchange mini-column

A simple and rapid preparation of LDH-1 and LDH-5 from heart and liver homogenates is described. The preparation is carried out on a 3 ml mini-column of DEAE-Sephadex A-50. The fractions of heart homogenate containing LDH-1 were eluted with an NaCl gradient after salt elution of other isoenzymes. This semi-purified fraction was re-applied to a second column and the whole cycle was repeated. This procedure takes less than 90 min to complete and a 70% yield of LDH-1 can be obtained. The fractions of liver homogenate containing LDH-5 were eluted by simple washing of the gel column with Tris-HCl buffer. The semi-purified fraction was re-applied to a second column and the wash procedure was repeated. This preparation took less than 30 min to complete and a 70% yield was obtained. No apparatus other than a small mini-column is required for this purification.