Gerald M. Edelman began working to the structure of antibodies when joined as graduate student the laboratory of Henry Kunkel in 1958 at the "Rockefeller University" in New York, obtaining his doctorate in 1960. Edelman's focus on the structure of antibodies led to the 1972 Nobel Prize in Physiology or Medicine along with Rodney R. Porter. Edelman and Porter decided to approach the problem of antibodies structure by splitting. In 1959, Porter published a report in which he used the enzyme papain to cleave the antibody molecule into three pieces of about 50,000 Da, corresponding to the two Fab (antigen-binding) and constant Fc (crystallizable) fragments. In the same year, Edelman showed that reduction of the disulfide bonds of antibodies in the presence of denaturizing agents led to dissociation of the molecule into smaller pieces, now known to be the light (L) and heavy (H) chains.