Elastin-fluorescein is prepared by labeling Elastin (EPC No. E60) with fluorescein-isothiocyanate (isomer 1) and milling to particle size 200-400 mesh (75-37 micron).
Soluble peptides absorb maximally at 495 nm.
Fluorescence should be determined using excitation of 490 nm and emission of 520 nm.
The 200-400 mesh size is recommended as substrate for the quantitative analysis of elastolytic activity. The assay can indicate as little as 0.4 µgram of crystalline elastase per ml of incubation volume. Smaller than 37 micron size ( EPC No. ES80) is advantageous as substrate in the elastase diffusion plate. The minute particles form a fine, homogenous dispersion in the agar gel. Zones of elastolysis are usually free of elastin particles yielding clear boarders.
Our method of assay with Elastin-Fluorescein can be found under Methods.
Preparation of the elastase diffusion plate with Elastin-Fluorescein (EPC No. ES80) can be found under Methods. You can also purchase the plates, EPC No. A622 and A622B, Alphasin�, Elastase Diffusion Plates.
This elastin is insoluble in biological buffers.