  We demonstrate that powder diffraction data can be collected from sub-micron
crystals of a mbrane protein with nearly two orders of magnitude more atoms
than the molecules commonly used for powder diffraction. The crystals of
photosystem-1 protein were size-selected using a 500 nm pore- size filter and
delivered to a soft x-ray beam with a photon energy of 1.5 keV using a
dynamically focused micro-jet developed for the serial crystallography
experiment at beamline 9.0.1. The 10-micron jet places many such randomly
oriented crystals in the x-ray beam simultaneously resulting in a powder
diffraction pattern which extends to 28 angstrom resolution with just 200
seconds of x-ray exposure. The use of the jet for particle delivery allows for
a thin sample, appropriate for the soft x-rays used, and continuously refreshes
the crystals so that radiation damage is not possible. The small size of the
crystals requires the use of lower energy photons for increased scattering
strength and increased spacing between powder rings. The powder patterns
obtained in this way, from abundant nano-crystals, could be used to provide low
resolution molecular envelopes if phased using techniques such as compressive
sensing which do not require atomic resolution data. The results also serve to
test our aerojet injector system, with future application to femtosecond
diffraction in Free Electron X-ray Laser schemes, and for Serial
Crystallography using a single-file beam of aligned hydrated molecules.
