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Title: Improvements in serial femtosecond crystallography of photosystem II by optimizing crystal uniformity using microseeding procedures

In photosynthesis, photosystem II (PSII) is the multi-subunit membrane protein complex that catalyzes photo-oxidation of water into dioxygen through the oxygen evolving complex (OEC). To understand the water oxidation reaction, it is important to get structural information about the transient and intermediate states of the OEC in the dimeric PSII core complex (dPSIIcc). In recent times, femtosecond X-ray pulses from the free electron laser (XFEL) are being used to obtain X-ray diffraction (XRD) data of dPSIIcc microcrystals at room temperature that are free of radiation damage. In our experiments at the XFEL, we used an electrospun liquid microjet setup that requires microcrystals less than 40 μm in size. In this study, we explored various microseeding techniques to get a high yield of monodisperse uniform-sized microcrystals. Monodisperse microcrystals of dPSIIcc of uniform size were a key to improve the stability of the jet and the quality of XRD data obtained at the XFEL. This was evident by an improvement of the quality of the datasets obtained, from 6.5 Å, using crystals grown without the micro seeding approach, to 4.5 Å using crystals generated with the new method.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [2] ;  [1]
  1. Humboldt Univ. of Berlin, Berlin (Germany); Technische Univ. Berlin (Germany). Max-Volmer-Lab. fuer Biophysikalische Chemie
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Biosciences Div.
  3. Humboldt Univ. of Berlin, Berlin (Germany)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1190859
Grant/Contract Number:
AC02-05CH11231; GM055302
Type:
Accepted Manuscript
Journal Name:
Structural Dynamics
Additional Journal Information:
Journal Volume: 2; Journal Issue: 4; Journal ID: ISSN 2329-7778
Publisher:
American Crystallographic Association/AIP
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 59 BASIC BIOLOGICAL SCIENCES