• crystallization;
  • seeding;
  • nucleation;
  • screening.

A microseed-matrix procedure has been established with the aim of influencing the nucleation event in standard crystallization screens. The method is based on the original description of matrix seeding described by Ireton & Stoddard (2004, Acta Cryst. D60, 601–605). Seed stocks are produced using a simple `seed-bead' method. The protein, reservoir solutions and seed stocks are pipetted simultaneously using a three-bore dispensing tip in drops of 0.6 µl total volume. The number and type of hits produced with the proteins tested in this study has been increased and it is believed that this method could be generally applicable to proteins where little or no nucleation is normally observed.