biostudies-literatureKoopmann RNIGMS NIH HHS259-62https://www.ebi.ac.uk/biostudies/studies/S-EPMC3429599biostudies-literatureUnknown9(3)Protein crystallization in cells has been observed several times in nature. However, owing to their small size these crystals have not yet been used for X-ray crystallographic analysis. We prepared nano-sized in vivo-grown crystals of Trypanosoma brucei enzymes and applied the emerging method of free-electron laser-based serial femtosecond crystallography to record interpretable diffraction data. This combined approach will open new opportunities in structural systems biology.Nature methodsIn vivo protein crystallization opens new routes in structural biology.PMC3429599R01 GM095583Martin AVAndreasson JDoak RBWeidenspointner GCaleman CBarty ABetzel CUllrich JWilliams GJRolles DRudenko ASchulz JShoeman RLLiang MMaia FRTimneanu NWang XChapman HNStellato FSchlichting IMesserschmidt MKimmel NCupelli KHajdu JFromme PWhite TAKassemeyer SBostedt CHampton CYStern SReich CBozek JDHauser GWunderer CBBogan MJKoopmann RRudek BEpp SWGraafsma HKirian RAWeierstall UStehle THirsemann HSpence JCDuszenko MSoltau HDeponte DPDavidsson JAquila AHartmann RLomb LGumprecht LSierra RGErk BRedecke LSeibert MMFleckenstein HRehders DHartmann AHunter MSEkeberg TStruder LBarthelmess MBajt SBoutet SCoppola NNass KFoucar LHoll PfalseIn vivo protein crystallization opens new routes in structural biology.Protein crystallization in cells has been observed several times in nature. However, owing to their small size these crystals have not yet been used for X-ray crystallographic analysis. We prepared nano-sized in vivo-grown crystals of Trypanosoma brucei enzymes and applied the emerging method of free-electron laser-based serial femtosecond crystallography to record interpretable diffraction data. This combined approach will open new opportunities in structural systems biology.2012-01-01T00:00:00Z2012 Jan2026-04-29T13:25:12.27Z2026-04-07T15:15:09.646ZS-EPMC34295992228638410.1038/nmeth.1859