An acetone powder is the simplest way to turn a fresh organ into something you can weigh out of a jar a year later. The method is older than most of modern biochemistry and it has survived because it does one job well: it takes the water and lipid out of tissue and leaves the proteins, and a good deal of their activity, behind.
How it's made
Fresh tissue is minced and homogenized in several volumes of cold acetone. The acetone draws water and lipid out of the tissue and precipitates the proteins, which are collected by filtration or centrifugation. The wash is repeated until the acetone runs clear, then the cake is dried under vacuum or in a stream of air. What comes out is a fine, pale powder that stays stable for years if it is kept dry and cold.
With the water and lipid gone the powder is concentrated, so a gram of powder stands for several grams of the starting tissue. Cold acetone is a mild denaturant compared with heat or stronger solvents, which is why many enzymes survive the process and can be recovered by extracting the powder back into buffer.
Where the powders end up
The biggest use is in coagulation reagents. Rabbit brain acetone powder is the classic starting material for prothrombin-time reagents and for the phospholipid fraction in aPTT reagents. The tissue source and the preparation set the reagent's sensitivity, which is why reagent manufacturers care so much about lot consistency (see why quality and traceability matter in coagulation reagents).
The second is antibody pre-adsorption: stirring a polyclonal antiserum through a powder from a non-target tissue removes cross-reactive antibody before a blot or a stain. The protocol is in using acetone powders for antibody pre-adsorption.
Powders from liver, kidney, muscle and other organs are also a convenient, shelf-stable source of tissue enzymes for kinetics work, and of antigen for raising or testing antibodies.
Handling and storage
Store the powder dry at −20 °C and let the container warm to room temperature before you open it, so it doesn't take up moisture. To extract, suspend the powder in cold buffer at the ratio your protocol calls for, stir at 4 °C, and clarify by centrifugation. Extracts don't keep the way the powder does. Make them fresh or freeze them in aliquots.
Our acetone powders come from rabbit tissue we collect in house and from bovine and other species we source for the purpose, so the origin of the tissue is documented for every lot. If you need a tissue we don't list, or more than the catalog quantity, tell us what you're making and we'll quote it.