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High resolution data set of Protein XX on a Big MAR

A high-resolution data set (2.2) has been collected on a crystal of protein XX on the Wiggler line (X25) of the National Synchrotron Light Source (NSLS), Brookhaven, Long Island, USA. The data were collected by Mia Raves, Raimond Ravelli and Michal Harel, end of October, 1995 using a Big MAR detector. The spindle axis comes from the left seen from the direction of the beam, and lies with the beam in the horizontal plane.

The unit cell of the crystal is 111.9 111.9 137.5 90 90 120, spacegroup . The wavelength was , the crystal to detector distance 235 mm. No theta offset was used: x beam 149.8 y beam 149.6. A total of 120 frames of 0.75 degree oscillation were collected, starting at spindle angle -60.5. A number frames were empty during the collection of first 45 frames (due to problems with the detector); we will only treat the integration and scaling of frame numbers 46 up to and including 120 (spindle angle 153.25 up to 209.5).

After indexing, refinement and integration of the first frame, STRATEGY was run. Figure gif shows the minimal needed oscillation range as a function of the starting spindle angle for a 100% complete data set in the resolution range of 4.0 - 2.2 (the low resolution reflections were collected in a different run).

  
Figure: Minimal total oscillation range as function of the starting spindle angle for a 100% complete data set of protein XX

The absolute minimum of this figure lies at the starting spindle angle of 163.4 degrees (needed oscillation range 53.4 degrees). The minimal oscillation ranges for the different total completenesses are given in the following table.

  
Table: Minimal oscillation ranges for different completenesses for datacollection on protein XX at X25, NSLS

One can conclude from this table that it would had been better if the data collection (starting angle 153.25, ending angle 209.5) was continued for a few more frames. However, the predicted completeness was still pretty high, as can be seen by running STRATEGY using the NFRAme 74 command.


Table of redundancy and completeness for a data collection of 74 frames, starting at the spindle angle 333.25 and with an oscillation range of 0.75 degree(s). Shell Summary of predicted redundancies by shells: Lower Upper No. of reflections with given No. of predictions limit limit 0 1 2 3 4 5-6 7-8 9-12 13-19 >19 completeness

4.00 3.71 37 339 451 305 363 506 135 0 0 0 98.27 3.71 3.49 33 304 485 323 325 534 125 0 0 0 98.45 3.49 3.32 34 298 516 313 318 547 117 0 0 0 98.41 3.32 3.17 27 260 555 304 308 549 110 0 0 0 98.72 3.17 3.05 30 247 579 304 286 558 101 0 0 0 98.57 3.05 2.95 31 219 587 327 280 584 96 0 0 0 98.54 2.95 2.85 27 211 608 329 267 569 96 0 0 0 98.72 2.85 2.77 27 197 609 358 266 573 87 0 0 0 98.72 2.77 2.70 28 187 618 347 252 591 86 0 0 0 98.67 2.70 2.63 23 186 606 380 244 588 80 0 0 0 98.91 2.63 2.57 21 179 614 380 249 577 84 0 0 0 99.00 2.57 2.52 18 176 612 402 238 596 76 0 0 0 99.15 2.52 2.47 17 170 628 397 235 563 74 0 0 0 99.18 2.47 2.42 12 168 608 408 236 584 77 0 0 0 99.43 2.42 2.38 10 176 594 420 231 581 73 0 0 0 99.52 2.38 2.34 7 183 601 463 237 567 75 0 0 0 99.67 2.34 2.30 3 176 572 458 231 547 67 0 0 0 99.85 2.30 2.26 1 184 598 470 229 587 70 0 0 0 99.95 2.26 2.23 1 188 567 466 230 554 74 0 0 0 99.95 2.23 2.20 0 163 568 501 232 556 73 0 0 0 100.00 All hkl 387 4211 11576 7655 5257 11311 1776 0 0 0 99.08

Running DENZO and SCALEPACK the following completeness table was obtained (before rejecting any bad-merging intensities).

Shell Summary of observation redundancies by shells: Lower Upper No. of reflections with given No. of observations limit limit 0 1 2 3 4 5-6 7-8 9-12 13-19 >19 total 4.00 3.71 98 387 456 306 319 462 108 0 0 0 2038 3.71 3.49 71 372 478 300 310 496 102 0 0 0 2058 3.49 3.32 62 361 515 312 298 507 92 0 0 0 2085 3.32 3.17 51 341 552 314 277 486 84 0 0 0 2054 3.17 3.05 60 330 582 334 264 459 80 0 0 0 2049 3.05 2.95 67 323 584 338 249 489 71 0 0 0 2054 2.95 2.85 57 302 627 313 255 481 69 0 0 0 2047 2.85 2.77 48 288 630 329 263 516 61 0 0 0 2087 2.77 2.70 54 268 627 301 249 541 65 0 0 0 2051 2.70 2.63 43 247 637 347 251 519 67 0 0 0 2068 2.63 2.57 47 245 638 316 266 529 51 0 0 0 2045 2.57 2.52 34 254 652 355 227 546 50 0 0 0 2084 2.52 2.47 44 240 651 341 252 514 56 0 0 0 2054 2.47 2.42 25 215 662 342 259 537 39 0 0 0 2054 2.42 2.38 39 226 645 367 285 499 33 0 0 0 2055 2.38 2.34 21 237 662 400 278 473 35 0 0 0 2085 2.34 2.30 15 227 668 412 313 450 22 0 0 0 2092 2.30 2.26 11 231 677 407 301 443 18 0 0 0 2077 2.26 2.23 12 252 681 421 340 375 15 0 0 0 2084 2.23 2.20 13 231 669 456 348 359 17 0 0 0 2080 All hkl 872 5577 12293 7011 5604 9681 1135 0 0 0 41301

The prediction is again too optimistic. This is due to the weak intensities of these high resolution reflections: more than 100 spots were deleted for each frame due to sigma cutoff (the default sigma cutoff of -3.0 was used in SCALEPACK). Also the mosaicity was high (0.7) which leaded to some overlap. The number of overlapping reflections increased significantly for the last few frames, which was (probably) the reason why the data collection was not continued further.



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