Crystallisation and preliminary X‐ray diffraction studies of cyclophilin‐tetrapeptide and cyclophilin‐cyclosporin complexes

Abstract

Recombinant human cyclophilin has been co-crystallised with a number of peptides to give crystals suitable for X-ray analysis. The crystal complexes for which heavy-atom derivatives have been prepared and X-ray data collected are: cyclophilin with N-acetyl-Ala-Ala-Pro-Ala-amidomethylcoumarin (I) which crystallises in space group P2,2,2, with a = 108.2, b= 123.0, c = 35.8 A, and cyclophilin with cyclosporin (II) which crystallises as tetragonal plates in space group P4,2,2 or P4,2,2 with a = b = 94.98, c = 278.55 A.

Crystal structures of cyclophilin A complexed with cyclosporin A and N-methyl-4-[(E)-2-butenyl]-4,4-dimethylthreonine cyclosporin A

“…Our CyPA-CsA structure is very similar to the decamer sandwich recently reported by another group [32] although the two crystals were grown under totally different crystallization conditions and have different space groups -P2 1 versus P4 3 2 1 2 [36]. In addition, most hydrogen bonds within the decamer are common between the monoclinic and tetragonal structures, indicating that the different crystallization conditions do not change the packing of CyPA-CsA.…”

Cyclosporin A—cyclophilin complex formation A model based on X‐ray and NMR data

“…which showed that the conformation of bound CsA is fundamentally different from both the NMR structure of free CsA determined in chloroform [ l6.17] and the X-ray CQ%I~ structure of CsA [16]. An X-ray structun: of CsA bound to cyclophilin has not yet been determined: all crystal forms of the ~~Iophilin-CsA complex yet obtained have multiple spies of the complex in the asymmetric unit [18]. In this paper we present a model of the CsA-cyclophilin complex based on the refined X-ray crystal structure of cyclophilin in rhe complex with ac-Ala-Ala-Pro-Alaamt.…”

Crystallization of the complex between cyclophilin A and cyclosporin derivatives: the use of cross-seeding

“…Recombinant human cyclophilin A was overexpressed in E. coli and purified as described elsewhere (Zurini et al, 1990) and concentrated to 18 mg ml-1 in 0.02% NAN3. CsA analogs were synthesized according to the methods previously reported (Wenger, 1989 …”

“…The exact concentration of isopropanol in the droplet was reported to be crucial for the growth of the different crystal forms of the CypA/CsA complex from ammonium sulfate solutions (Zurini et al, 1990). In the cross-seeding and spontaneous nucleation experiments in PEG solution, the growth of the crystals seemed rather insensitive to the presence of 1-5%(v/v) isopropanol, 0.2-0.5%(v/v) …”

“…Using ammonium sulfate as the precipitant, different crystal forms of the complex between CsA and CypA could be grown: a monoclinic form, a hexagonal form and a tetragonal form (Zurini et al, 1990). All have large unit cells (volume greater than 2 x 106 A 3) and contain a pentamer or a decamer of complex in the asymmetric unit.…”