Proteolytic enzymes past and present: The second golden era

I first met Max Perutz when we were both chemistry students at the University of Vienna, where we also shared a passion for skiing. Our love for proteins brought us together again during our professional careers and aroused my admiration for his brilliant scientific ingenuity and achievements. The present autobiographical vignette is contributed as a token of my appreciation of our friendship. The study of proteolytic enzymes has occupied a central position in protein chemistry from its early beginnings and has remained so throughout the past 60-odd years. The fascination with this group of macromolecules derived in part from the fact that substrates, inhibitors, as well as the catalysts themselves, all were proteins of unknown composition and structure and