This polypeptide example illustrates a number of features found in ORTEP-III. The data for the example were taken from the Protein Data Bank #216L. The header information from that file is provided below. HEADER HYDROLASE(O-GLYCOSYL) 10-MAY-94 216L COMPND LYSOZYME (E.C.3.2.1.17) MUTANT WITH SER 44 REPLACED BY TRP, COMPND 2 CYS 54 REPLACED BY THR, CYS 97 REPLACED BY ALA (S44W, COMPND 3 C54T, C97A) SOURCE BACTERIOPHAGE T4 (MUTANT GENE DERIVED FROM THE M13 SOURCE 2 PLASMID BY CLONING THE T4 LYSOZYME GENE) AUTHOR M.BLABER,B.W.MATTHEWS REVDAT 1 31-JUL-94 216L 0 SPRSDE 31-JUL-94 216L 116L JRNL AUTH M.BLABER,X.-J.ZHANG,B.W.MATTHEWS JRNL TITL STRUCTURAL BASIS OF ALPHA-HELIX PROPENSITY AT TWO JRNL TITL 2 SITES IN T4 LYSOZYME JRNL REF SCIENCE V. 260 1637 1993 JRNL REFN ASTM SCIEAS US ISSN 0036-8075 0038 Only the first 63 amino acids (500 atoms) of this protein were used for this example since that is the size used in the dimension statements in the program. The first 500 ATOM lines were extracted from the PDB file and placed unaltered in a file named ATOMS.DAT. Since the atom data in ATOMS.DAT are not in the standard format used by ORTEP, subroutine READIN in the ORTEP source code was written to read ATOMS.DAT. In the ORTEP input file LYSO.DAT, a "2" in column 1 of the final symmetry card tells ORTEP that (1) the atom data is in a separate file and (2) to use READIN to read the data. As each atom is read by READIN, the subroutine sets the value of FEATURE #2 (id2) for the atom to the sequence number of the amino acid containing the atom. FEATURE #1 (id1) is set to a value that indicates the type of atom: 1 peptide link N 2 alpha carbon 3 carbon of C=O in peptide link 4 oxygen of C=O in peptide link 9 all other atoms The input file LYSO.DAT contains the instructions for producing three different illustrations from the same input data. Each begins with a 201 instruction and ends with a 202. The second and third sets make use of the assigned atom features to select particular atoms for drawing.