Human leukocyte elastase

[littlemok]

Does anyone have any suggestions for suspending and storing elastase in aliquots and the how long it can be stored like this for? Many thanks

[CharonY]

For long term storage lyophilization and storing it cold is probably the best. It still has decent activity after ~6 months and more. If you want to store it in solution use a alkaline buffer ~pH 8, avoid glass wares, as it readily adheres to it. If it is only for a couple of days I'd store it at 2-4°C, as freeze/thaw cycles rapidly reduces elastase activity (true for all proteins).

[littlemok]

thank you. It comes as a lyophilized powder (1 unit) and I was advised by the company to suspend it in saline below pH6 and preferably at pH5.3 which I did but I have no activity. Thanks for your advice - will definitely look at that.

[CharonY]

Sorry, I have to retract part of my statement. I remebered using a pH 8 buffer at one point, but it wasn't my storage buffer.

Elastase has a higher solubility and activity at alkaline pH (that's when I used a pH 8 buffer), but for storage I also used a buffer around 5.5 in order to avoid activity loss.

So ideally store it as powder. After resuspending it, you should aliquot it (for one assay each) and store at -20°C which should work for at least a month (if memory serves). At 4°C it loses activity after a week or so (in my hands).