A.M. Pappenheimer, Jr.

On a spring morning in 1926 a Harvard freshman picked up the CRIMSON and read that a new field of concentration had received Faculty approval. That same day he enrolled in Biochemical Sciences, becoming the first student in the program. The freshman, A.J. Pappenheimer, Jr., apparently was satisfied with his choice, for he remained in the University to do graduate work under James Bryant Conant. And, at present, he is Chairman of the Board of Tutors in Biochemical Sciences.

Several weeks ago, Professor Pappenheimer was appointed Master of Dunster House. He is to succeed Gordon M. Fair next February, following a Fall Term sabbatical leave. His selection represents more than the obvious desire to maintain a scientist among the Masters: it is a tribute to his ability to combine both research and effective, individualized instruction.

Throughout his research career Pappenheimer has retained a keen interest in infectious disease. In particular, the diphtheria bacillus has fascinated him. This microscopic organism produces one of the most potent poisons known in biology. The toxin is, in fact, so powerful that a few molecules of it suffice to kill a cell. An easily made by product of the toxin, diphtheria toxoid, is harmless and serves as an excellent immunizing agent. With the virtually universal immunization of children in Europe and the United States, diphtheria has been "licked" in the medical sense. But it still provides many challenging biological questions.

Pappenheimer has endeavored to analyze the action of the toxin right down to the molecular level, in order to determine the ultimate biochemical reasons for its destructive potency. This problem has taken him into many fields. From a commercial laboratory he learned that traces of iron reduce the yield of toxin. He was able to determine that the production of a pink pigment called coproporphyrin was similarly diminished by iron. This discovery in turn led him back to work he had done as a graduate student.

With Conant, Pappenheimer had developed an improved method for measuring the oxidation potentials of hemoglobin. In addition, he had conducted research on cytochromes, iron-containing enzymes which are closely related to hemoglobin. Cytochromes fulfill an important function in the oxidative processes of metabolism in many organisms. Since diphtherial cytochrome is probably a derivative of coproporphyrin, the dual inhibiting effect of iron suggested that the toxin operates by "impersonating" cytochrome.

To test this theory Pappenheimer needed an experimental animal in which the blocking of cytochrome synthesis would produce readily detectable effects. The Cecropia silk worm satisfied the requirement. During both the caterpillar phase and the period of adult development Cecropia produces substantial quantities of cytochromes. In the dormant pupa stage, though, the enzymes occur in only trace amounts. By showing that resistance to diphtheria toxin in the pupa stage is much greater than during other phases, Pappenheimer furnished compelling evidence for his theory.

Moreover, at the undergraduate level, Pappenheimer favors general scientific training rather than narrow specialization. "The whole raison d'etre of Biochemical Sciences," he maintains, "is the feeling that advances in biology and medicine are dependent upon the broad tools of science."

With respect to the fissure between science and the humanities, Pappenheimer places most of the blame on the non-scientists. Many natural science concentrators enroll in upper level literature and history courses, he notes, but few students in humanities or social sciences have the desire or necessary skills to take comparable science courses. Considering the extensive training required in the natural sciences, he doubts whether the layman will ever fully appreciate the aims of the scientist.

In addition to giving a graduate course in immunology, Pappenheimer provides tutorial instruction for many undergraduates. According to one tutee, "He always asks the toughest questions, but in a mild manner." It is this combination of rigorous academic standards and pleasant mien which has made Pappenheimer such a popular tutor.

Currently, Pappenheimer is a Fellow of Kirkland House. When the members of the House heard of his "desertion" to Dunster, the immediate reaction was "We've lost our best squash player." Another of his athletic interests is skiing. He also plays the viola and clarinet.

During his Fall Term sabbatical at the University of Amsterdam, Pappenheimer plans to study the broad topic of oxidative phosphorylation. Of particular interest to him is ATP, the major energy-storing compound of the living cell. ATP is involved in the cytochrome oxidizing processes mentioned above. Thus, Pappenheimer's work at Amsterdam will probably yield additional information concerning his old friend, diphtheria toxin.