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ing specificity type. I t suggests further t h a t (a) the common sequence around serine is involved in making the otherwise inert CH20H side chain reactive and (b) the amino acids responsible for the specificity lie further from the reactive serine, perhaps in adjacent coils. \Vhile there must be an intimate steric relation between the amino acids responsible for the catalytic action and those rcsponsible for the specificity, these results indicate that the two may be separable. In this case conimon sequences related to specificity as well as to the bond-breaking action might be expected, a result which would be of enorinoiis value in relating enzyme structure to function.
acetone and the incubation continued for 24 hours longer. Extraction of the culture with ethyl acetate, followed by chromatography on silicic acitl . crystallization from hexane-acetone, and sub1ini:itioii a t 90b11.5° (0.000,5 mrn.) afforded 20.3 xng. o f IT', n i . ~ ) 140.,j-141° . (no depression on adniixturr. with an authentic sample); [ a ] ? b+ ~1 2 3 O (c 1.04. in CHC1:J; XE:P, 243 mp ( E 16,200); sulfuric ncj(1 chromogenss were identical with a known sariiplc (peaks a t 2G5, 305 and 390 (broad) and a minilnuin a t 2% nip); (Anal. Found: C, R0.08; H, S.16. Calcd. for CI9Hz4O2:C , 80.21; H, S.51); infrared analysis showed Agfl 5.77 p (17-ketone), 6.04, 6.17 arid 6.25 ,u (A1*4-3-ketone),identical with an ailtheritic sample. Mixed paper chromatography BIOLOGYDEPARTMENT BROOKHAVEN YATIOSAL L.4BORAToRY D. E. KOSHLAND, JR. showed no separation from authentic 1x7. UPTON,L. I . , KEWYORK MARYJANE E R U I Y In similar experiments, conversions in good yield RECEIVED APRIL 15, 1957 of I and 111 to IV were demonstrated and the products rigorously identified by comparison paper ENZYMATIC INTRODUCTION OF DOUBLE BONDS chromatography, m.p. and infrared spectra. Evidence for the presence of small amounts of V in each INTO STEROID RING A case was obtained. Conversion of 1S-nor-testosSir: terone by the same system in 72 hours gave a 67 ' The introduction of unsaturation into ring A of yield of estrone 1 n . p . 253--236'; [a]"D f 1.isteroids is of interest in connection with the aro- (c 0.644, in dioxane); 28%m,u ( E 1960); on admatization involved in biosynthesis of estrogens, dition of XaOH, 243 m p ( E 8000) and 300 nip and in the microbiological formation of A'-dehy- ( 6 2500). The infrared spectrum showed peaks a t drosteroids, some of which possess interesting
