H A N S FISCHER (1881At the Harvard Tercentenqv exercises in September. 1936, an honorary doctorate was conferred on Hans F~scher with the citation: A master builder of molecular structure, whose labors
n s , a combination and plant leaves. They are c h r ~ m o ~ ~ o t e iire., of a colorless protein and a pigment; the latter is chiefly responsible for the functioning of the chlorophyll and the hemoglobin. Both are pyrmle derivatives (Kiister, Nencki). The oub standing difference is that the central atom of chlorophyll is magneshm, of hematin, iron. Removal of the iron from hemin'(hematin hydrochloride) leads to the production of the so-called porphyrins (Hoppe-Seyler). These are easilv recognized through their characteristx spectra. Similar porphy'rins are obtained by removing the magnesium from ~hlorophyll,clear evidence of the close relationship of the two pigments. Porphyrins are widely distributed in nature. Patients suffering from porphyrinuria, a metabolic disturbance, excrete large quantities of coproporphyrin and uroporphyrin. A complex copper salt of the latter occurs in the ~ i n feathers g of a n African bird related to the cuclioo. Pearl-oyster shells contain the calcium salt of conchoporphyrin. Traces of coproporphyrin occur normally in urine, also in bottom yeast, where improper propagation often leads to a considerable increase so that the .veast . suffers from a condition comDarable t o animal porphyrin-
A thorough study of the chemistry of the pyrroles was a necessary preliminary to the conquest of the main problem. Using the s t u d m of Know and Paal as n foundation, Hans Fischer and his collaborators spent many years systematically extending the knowledge of these compounds. All the building blocks.oF chlorophyll were synthesized, numerous methods of pre armg porphyrins were discovered and developed so that exampEs are known in the laboratory that have not been found in nature or obtained from hemin. The way to the synthesis of hemin was paved by about twenty years of this type of research. The greatest obstacle was the existence of isomers, not less than fifteen are predicted by theory. Th? s "thesis of hemin (C1,HJ20rN.FeCI) has now been acomplrsheg. Chlorophyll presents a task of different proportions thou h success may be reached in the not-too-d~stantfuture. Thus ar i t has been established that the side chains have the same arrangement as in hemin: also the vorvhyrins resultmg from the deep-
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Munich: Ph.D: (1904)? M.D. (1908). A thorough training in res~onsibleasnstantshws in the cllnlcs a t Munich and in Emil
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1918he m o k d Vienna as success% t o Mauthneg and in1921 he took his resent positmn when he succeeded W~elandin Munich as h e a l o f the organic chemical institute of the Technical
una.
The spots on the eggs qf the gull, plover, and other birds that nest in the open contain 06porphyrin. This is identical with Kimmerer's porphyrin produced by putrefaction of blood. Prolonged putrefaction ofhlood leads to deuteroporphyrin, the starting material for the synthesis of hemin.
chiefly on bile pigment, and so forth.
chloroph.vll, pyrrole derivatives, blood I n 1930 he was awarded the Nobel Prize.
(Contrihufrd b y Ralph E. Ocsper, Uniuersify qf Cincinnati)
