Proteins, Pep tides and Amino Acids SourceBook is the second in a series of reference books conceived to cover the explosive growth in commercially available biological reagents. The success of our first reference work, Source Book of Enzymes published in 1997, encouraged us to continue this series. Choosing proteins, peptides, and amino acids as the subject matter for the second volume was simple, given their preeminence in regulating biochemical processes and their importance to modern molecular biology. The SourceBook series was inspired by our difficulty in locating a suitable replacement for a depleted reagent in the midst of an urgent research project. To our dismay, we found the reagent supplier out of business and the product line no longer available. Other reagent catalogs on our library bookshelf offered a narrow selection and incom­ plete functional information. We were ultimately able to locate a satisfactory alternative only by making countless inquiries and paging through innumerable product catalogs and technical data sheets. We needed-but could not find-a single resource that cataloged available compounds, organized them in a logical and accessible format, provided critical technical information to distinguish one from another, and told us where we could buy them.