X-ray analysis and protein structure.

PAGES I. Illtroductiorl.. .......................................................... 134 II. The Nature of X-Ray DifTraction. ....................................... 135 1. Diffraction from a Crystal ............................................ I35 a. Crystal Lattice and Reciprocal Lattice. ............................ 137 b. Structure Determination ........................................... I39 c. Symmetry..........................................................l4 0 2. Diffraction froma Fiber ............................................... 142 a. The Interpretation of Fiber Diagrams .............................. 144 3. Stereochemistry and Molecular Packing. .............................. I46 4. General Remarks. . : ...... .: .......................................... I51 5. Sulnmary ............................................................. 153 III. Fibrous Proteins and Synthetic I’olypeptides .............................. I54 1. Synthetic l’olypeptides (and Silk). .................................... 154 a. a-l’olypcptides .................................................. 155 b. &l’olyprptides and Silk. ......................................... 158 c. I’olgproline. ................................................. 159 d. I’olgglgcine ................................................ 159 2. Fibrous l’rofeins .................................................... 163 a. The n-Kcral.in I’:lf.tcrn ..... ... ......................... lC3 b. The fl-Kcratin l'attcw ......................................... 165 c. Coll:1gcrt ................................................... IGG IV. Crystalline I’rotcius. .................................................... 170 1. The Nature of Protein Crystals ...................................... 170 2. Direct Information ................................................... 174 a. Unit Cell and Space Group ......................................... 174 b. hlolecular Weight .................................................. 175 c. Identification and Identity ......................................... 176 d. The Shape of Protein Molecules ................................... Iii 3. The Patterson Function.. .. ......................................... Ii8 4. Methods Involving Heavy Atoms. ................................... Ii9 a. The IIcrvy Atom Method ..................................... Ii!) b. The Mnthotl of Isomorphotls Rel~laccmcut. .................... ISO c. Isnrnoq~l~nr~s Rcpl:~cmcut nntl the Strll(*turc of I~cmoglol~iu ........ ls3 d. Isomorphous Rcplncemeut and t,hc Structure of Myoglobio. ........ 18s