Why is your collagen degradation units per mg different than other vendors?

These results cannot be compared since different substrates and assay principles are used to measure this activity. VitaCyte’s kinetic fluorescent microplate CDA assay detects an increase in fluorescence as collagenase unravels and degrades fluorescein isothiocyanate conjugated to collagen fibrils. Measurements are made every 150 seconds.

By contrast, the Mandl is an endpoint assay where collagenase is incubated for 5 hours with collagen fibers. The assay tubes are centrfuged and a portion of the supernatant is assayed for free amino acids and small peptides using a reagent to detect free amine groups. After a two hour incubation, the results are compared to a standard curve using purified leucine. One enzyme unit is equivalent to the presence of one micromole of  leucine per minute in the supernatant.