An excellent intermediate-level overview of protein structure is the book Introduction to Protein Structure by Carl Branden and John Tooze (1991, Garland Publishing Co., New York). Kinemages are available for each chapter in this book (you will need the free viewer MAGE to view them).

• My nomination for the best treatment of protein secondary structure on the web is the animated and colorful yet thorough and quantitative treatment of protein G entitled Protein Architecture by Will McClure at Carnegie-Mellon University, Pittsburgh PA. This tutorial uses Chime for animated 3D views of structure. When you finish the tutorial, you can take McClure's fun 20-question Protein Architecture Quiz, where you answer by clicking on the molecular structure. More excellent biochemical resources will be found at McClure's Molecular Models for Biochemistry at CMU page.

• The Medical Biochemistry site at the U Kansas Medical Center includes Chime tutorials on protein secondary structure and domains. Avoid peak hours for viewing these as they are o so slo o o o o w to download.

• Protein Structure Tutorial by Andrew Coulson, University of Edinburgh UK. This text tutorial is designed to be used in conjunction with RasMol. It teaches recognition of the main elements of protein secondary structure, and the main structural classes of globular proteins. The tour begins with an examination of RNAse, continues with two alpha proteins (cytochrome B562 and myoglobin), two beta proteins (crystallin and retinol-binding protein), and two alpha/beta proteins (triosephosphate isomerase and flavodoxin). It ends with an open-ended exploration of a DNA-binding protein.

• Structure and Packing of the Alpha Helix, by Duane Sears and Debbie Richards, University of California, Santa Barbara. A detailed exploration of the structure of sperm whale oxymyoglobin, emphasizing use of the RasMol command line.

• Structure and Packing of the Beta Pleated Sheet, by Duane Sears, Tina Leuthard, Jason Gines, and Debbie Richards, University of California, Santa Barbara. A detailed exploration of the structures of the plant lectin concanavalin A, and the enzymes carboxypeptidase A and triose phosphate isomerase, emphasizing use of the RasMol command line.