The transfer of protein crystals from their original mother liquor to a solution with a completely different precipitant

A procedure is described for the transfer of protein crystals from an ammonium sulfate‐containing mother liquor to a solution with another precipitant, such as polyethylene glycol. The suitable concentration of the alternative precipitant is established via a novel protocol, using a hanging‐drop equilibration method. This crystal transfer procedure is illustrated by experiments with crystals of trypanosomal triosephosphate isomerase and bacterial p ‐hydroxybenzoate hydroxylase, but it might have more general applicability

Experiments in membrane protein crystallization

Experiments have been carried out aimed at obtaining crystals of three integral membrane proteins: phospholipase A, cytochrome-c reductase and cytochrome-c oxidase. Crystals, in the form of platelets and bipyramids, as well as several micro-crystal forms have been obtained of phospholipase A from the outer membrane of Escherichia coli. The best crystals obtained so far were thin plates having spacegroup C2221 with a = 72.0Å, b = 107Å, c = 75.8Åand one molecule per asymmetric unit. Reflections were observed out to 2.7Åresolution. Long red needles have been obtained of the respiratory chain complex-III, or cytochrome-c reductase, from beefheart

Crystals containing a single subunit type of Panulirus interruptus haemocyanin

Crystals have been grown of the 94K subunit of Panulirus interruptus haemocyanin. The best crystals were obtained by the “two-layer liquid diffusion technique” with ammonium sulphate solutions as precipitating agent. The crystals have space group P6322 with cell dimensions a=b=195·6and c=158·0 . The diffraction pattern extends to a resolution of approximately 3·0resolution. The unit cell may contain two hexameric molecules with 32 symmetry, i.e. one subunit per asymmetric unit.<br/