What's the difference between the *types* of tissue dissociation enzymes? I'm trying to dissociate a tumor, and most protocols like NCI/NIH recommend a 10X triple enzyme digestion stock consisting of: collagenase type IV, DNase I type IV and hyaluronidase type V in HBSS. This goes all the way back to the 90s, and the recipe varies between papers (dispase, papain, neutral protease, elastases, etc.). The so-called _official_ recipe that I've been tasked to use is composed of the above, however, mostly from Sigma-Aldrich (C5138, D5025, H6254) I can't really find anything that says what the real differences are between these types of enzyme are, however. Or why for example type IV DNase works better than type II, and so forth. Is it perhaps that the recipe just happened to stick?

It’s years since I looked at a Sigma catalogue (before it became Sigma-Aldrich) but as I remember, these designations are arbitrary proprietary ones used by Sigma to distinguish different sources — the key point being that Sigma didn’t generally manufacture all of these themselves, but obtained the from third parties.

The other point to note is that these enzyme preparations were/are generally impure, but to differing extents, so the type designations allowed you to re-order a particular preparation that worked, and also to specify the actual grade you used when you published so that other people could repeat your work. More expensive grades would, no doubt, also work in the sort of crude application you describe, but they would be a waste of money.

I thought the catalogues used to give you some information (organism/tissue at least), but, as I said, it’s been a long time (although be careful with your “way back to the ’90s”, young man).