38
edits
Cryo: Difference between revisions
no edit summary
No edit summary |
No edit summary |
||
| Line 16: | Line 16: | ||
It is proposed that freezing in liquid propane is faster and therefore better for a protein than in liquid nitrogen. Measurements with small thermocouples by Hakan Hope [http://www.bio.net/bionet/mm/xtal-log/1995-November/002005.html]revealed that there is almost no difference in cooling rates; cooling in liquid nitrogen was even faster than in liquid propane. On the other hand Teng and Moffat [http://scripts.iucr.org/cgi-bin/paper?wb0048] showed that flash cooling in liquid propane is fastest. In summary, some but not all crystals freeze 'better' in liquid propane than in nitrogen. Transport of crystals embedded in solid propane is easier than in liquid nitrogen: you can take your dry-shipper with you without any liquid nitrogen left in the container. | It is proposed that freezing in liquid propane is faster and therefore better for a protein than in liquid nitrogen. Measurements with small thermocouples by Hakan Hope [http://www.bio.net/bionet/mm/xtal-log/1995-November/002005.html]revealed that there is almost no difference in cooling rates; cooling in liquid nitrogen was even faster than in liquid propane. On the other hand Teng and Moffat [http://scripts.iucr.org/cgi-bin/paper?wb0048] showed that flash cooling in liquid propane is fastest. In summary, some but not all crystals freeze 'better' in liquid propane than in nitrogen. Transport of crystals embedded in solid propane is easier than in liquid nitrogen: you can take your dry-shipper with you without any liquid nitrogen left in the container. | ||
Here a short protocol how to prepare liquid propane and how to use it. | Here a short protocol how to prepare liquid propane and how to use it. | ||
* Cryogenic burns are painful. E.g. wearing a combination of cotton gloves and latex gloves protects from liquid propane and | * Cryogenic burns are painful. E.g. wearing a combination of cotton gloves and latex gloves protects from liquid propane and are not too bulky for crystal handling. | ||
* Use pure propane | * Use pure propane | ||
* Place a metal piece (e.g. big screw nut) into a 50 ml plastic ('Falcon') tube | * Place a metal piece (e.g. big screw nut) into a 50 ml plastic ('Falcon') tube | ||