Phasing at resolution higher than the experimental resolution.
Limited experimental resolution is a unavoidable feature in macromolecular crystallography: it may hinder or make difficult the determination of the crystal structure. A novel procedure is presented which from an approximate electron-density map extrapolates the moduli and phases of non-measured reflections beyond and behind the experimental resolution limit. Applications to a set of test structures show that the extrapolation can be successfully accomplished. As a consequence, the phase estimates of the observed reflections are subsequently improved and the interpretability of the corresponding electron-density map increases. The use of the extrapolated values for the non-measured reflections provides additional information for the map, which shows a resolution higher than the experimental resolution.
Caliandro
Rocco
R
Istituto di Cristallografia, CNR, Via Amendola 122/o, 70126 Bari, Italy.
Carrozzini
Benedetta
B
Cascarano
Giovanni L
GL
De Caro
Liberato
L
Giacovazzo
Carmelo
C
Siliqi
Dritan
D
D000465:Algorithms; D018360:Crystallography, X-Ray / Q000379:methods* / Q000706:statistics & numerical data; D004583:Electrons; D005583:Fourier Analysis; D012984:Software; D014961:X-Ray Diffraction / Q000706:statistics & numerical data