COMMUNICATIONS TO THE EDITOR
June 20, 1958
3165
tially no recoils will strike walls before thernialization, while all should be neutralized before chemical reaction. The Emzz0concentration was reproducible to i= 40%-each run was compared to a zero-delay run immediately preceding. The decay curve in each case showed the growth of TlZo8and BROOKHAVEN SATIONAL LABORATORYHARVEY M. LEVY daughters of Pbzl2,as well as Emzzzfrom Ra226in UPTON,XEWYORK D. E. KOSHLAND, JR. solution. RECEIVED MARCH28, 1958 The nature of the organo-lead compound(s) has not been established-the lower volatile percentages with longer delay times probably are caused by furFORMATION OF VOLATILE COMPOUNDS BY Pb2I2 ther reactions of the original species, leading to less RECOILING FROM ALPHA DECAY' volatile compounds. Sir: Volatile metallic products may prove useful for The discovery that tritium and halogen atoms, quick chemical separations of nuclear recoils from recoiling from nuclear processes, undergo sub- thin films. They may also help to explain low stitution reactions in the gas phase in high yield has gaseous diffusion coefficients observed for T12",'j prompted us to investigate the possibility of gas- and are important in measurements of bond-breakphase reactions for metallic atoms undergoing nu- ing accompanying p- decay such as in Pb?l0(CH3)4.' clear rec0i1.~-~Our experiments demonstrate the Other metallic recoil atoms are being studied. formation of volatile organo-lead compounds by (6) D. L. B a u l c h , J F. D u n c a n and J. P. R y a n , rbid., 10, 203 (1957). Pbzl2 atoms from the alpha decay of Po216in a (7) R . R. E d w a r d s , J. LI. D a y a n d R . F. O v e r m a n , J . Chem. Phys methane atmosphere. 21, 1555 (1953). The thoron (Emzz0)daughter activity in equi- DEPARTMENT OF CHEMISTRY OF KANSAS JACK R A Y librium with Th232 was removed from thorium nitrate UNIVERSITY F. S. ROWLAND KAXSAS solution by sweeping with carrier gas. The carrier LAWRENCE, RECEIVED APRIL 29, 1958 gas flowed through a cold trap, a 200-ml. storage bulb, and then was vented. After the system reached equilibrium, the bulb was shut off and by- INTERCONVERSIONS OF POLYRIBONUCLEOTIDES AND NUCLEOSIDE TRIPHOSPHATES' passed, and became a vessel for reaction of thoron decay products with sweep gas. The steady-state Sir: Ribonucleoside diphosphates have been shown concentration of EmZ2Oin the bulb was determined from a gas aliquot taken immediately after isola- to be the precursors oi pol\-ribonucleotitles in the polynucleotide phosphorylase reactions.? Ention from the flow system. The formation of volatile Pbzl2compounds was zymes catalyzing this reaction have since been denistudied by isolating the reaction bulb until the de- onstrated in extracts from a variety of microbi:il . ~ purified irom several difiercay of thoron to Pb2I2was essentially complete ( 2 and plant s o ~ r c e sand -In enzyme catalyzing the phos15 min.). An aliquot of the gas then was examined ent for PbZl2activity. An appreciable amount of the phorolysis oi adenylic polynucleotidc to ADP8 has Pb2l2in methane sweep gas was transferred with recently been isolated froin nuclei of mammalian the aliquot. The results of these experiments are liver.: Some evidcncc lias bcen accumulatctl, summarized in Table I. In similar experiments however, which suggests that the incorporatioil o i -\Ill' iiito polymeric material catalyzed by soluble TABLE I extracts from inammalian sources may utilize PERCENT.VOLATILE Pe21zFROM Poz14RECOILIP; GASEOUS .\TI' as the substratc.s-ll
The simplest explanation for these facts is that a phosphorylated intermediate, capable of exchanging oxygen with water, is formed in the myosin portion of the actomyosin. The actin can then attack this intermediate with formation of an actinmyosin bond which holds the protein in contracted form.
I
ATMOSPHERE Gas
Methane
Delay t i m e min.
Vola ti I e activity, %
15 30
38 20 14
45
Helium
60 330 15 30
19
5 0 0
with helium carrier, no Pb2l2activity entered the proportional counter. The range of Pb212 (128 k.e.v. recoil energy) is < 1 mm. in methane or helium a t STP,5but long enough to ensure equilibrium in charge-exchange processes. Therefore, essen(1) R e s e a r c h s u p p o r t e d by A.E.C. c o n t r a c t No. AT-(11-1)-407. (2) M. E l - S a y e d a n d R. W o l f g a n g , THIS J O U R N A L , 79, 3286 (1957). (3) A. G o r d u s , M. S a u e r , and J. Willard, ibid.,79, 3284 (1957). ( 4 ) J. Willard, el a!., J . Chrm. Phys.. 2 0 , 1556 (1962); 25, 904 (1956); THISJOURNAL, 75, 6160 (1953); 79, 4609 (1957). ( 5 ) D. L. B a u l c h a n d J. F. D u n c a n , Ausiral. J . Chem., 10, 112 (1957).
(1) Siipporreil by g r n n t i - i n - o l d So 11 2 l 7 i frz-om t h e S n t i o n a l He:srt I r i i t i t u t e . I-SPHS, from t h e Sation21 Science F o u n d a t i o n . a n d t h e Presented in :,art a t t h e h I e e t i n g of 1:11 Lilly K s i e a r c h Idior'itciries. t h e Amcricxn S o c i r t y L i B:uIogicd! C h e n i i l t s , l'hilndelpliia. April 1938. ' 2 ) .\I Griinl,erg-.\lannpo :ind S. Ochon, T H I S J ~ J W R S A L , 77. 3 1 C b (l9.iC-,);11. Grunberg-llanago, P. J. O r t i z a u d J. Ochoa S r i v i r e . 122, !G (19351' Hiochini. PI Bioph?s. . I d a . 20, 269 ( I 9 X J . (3) D . 0. Drummaind, .\I. Stnehulin a n d S. Ocliox. J . Bicl C ~ P I I I . . 226, 8% (!!Xi). (1) R. 17. Becrs, 177,7!10 (I!JiG\: Bit ~ P I U . I . . 66, \;8d (1957). ( 5 ) 1'. %. I.itrsuer, F @ ! r i a n d .I,K u r n l w r g . J . B2,i C ( 6 ) . \ L b r c \ i.itiun, used. tri.,tri.-(hydruxymtttiyl - a r n i n t , m e t h a n e . E'., inurgnnic :)ho*;,hare, PP.. i n n r g i n : c p y r o p h o s p h i t e . .ATP. :idenosine >'-tr:phu.ghatc. A D P , adenosine 5 ' - d i p h o i p h a t e , GTP. g u a n w i n e .*,'-triphsiyhste, CTP, u r i d i n e 3'.tril,husphate, CTP, c y t i d i n e 0't r i p h o s p h a t e , R S . 4 . ribonucleic :wid o r mixell pulyribonurleotide. c p m.. COII!!~; per ri:::iite ,iSove L ,:kZrc ah-orption. 7 1 K. J . IIilinoe srid I. .A He;,ptl, TUEJ M ' R S W , 79. it310 (IYYj7) (8) E. S. Cnnellakis, Hi
DurFtion, C.p.m. inmin. corporated
10 5 10 20 20 20 20 20 20
145 253 473 760 40 138 15 200 304
I )uration
min.
C.p.m. incorporated6
0 . 5 pmole total (0.125 pmole earli) 0.50 pmole 0.50 pmole 0 50 pmole 0 50 pinole Sone 12-r 577 232 y 348r 0.50 pmole total 0 . 5 9 pmole total
.5
1745
5 5 5 5 20 20 20 20 20 30 30
2385 1295 1200 1935 260 645 1876 2656 3456 2960 688
0.50 pinole total
30
0
or of polyribonucleotides, presumably as a source of the latter. The relation of the three activities to each other and to the net synthesis of polyribonucleotide is under investigation. DEPARTMENT OF CHEMISTRY INDIANA UNIVERSITY C. W. CHUNG INDIANA IS. R . MAHLER BLOOMINGTON, APRIL 19, 1958 RECEIVED
THE HEXOSAMINE MOIETY OF N-ACETYLNEURAMINIC ACID (SIALIC ACID)
Sir:
As previously reported, an enzyme obtained from Clostridium 9erfringens (N-acetylneuraminic acid aldolase; NANaldolase) catalyzes the following reversible reaction : N-acetylneuraminic acid = pyruvate N-acetyl-D-mannosamine (N-AcSoluble, crude enzyme preparations, from the Mm). In contrast to these results, data from other ~ that the hexosamine non-sedimentable fraction of homogenates of em- l a b o r a t o r i e ~ ~ -indicated bryonic chick hearts and livers catalyze the follow- moiety of N-acetylneuraminic acid (NANA) is Ning three reactions: (1) the incorporation of acetyl-D-glucosamine (N-AcGm), The present studPPi 3 2 into ribonucleoside triphosphates; (2) the ies suggest that the apparent discrepancy in the pyrophosphorolysis of S-RNA, a polyribonucleotide results obtained by the enzymatic' and c h e m i ~ a l ~ - ~ obtained from the non-sedimentable fraction of techniques is due to the interconversion of N-AcGm homogenates of embryonic liver by a phenol and N-AcMm under the alkaline conditions used methodg*12; (3) the incorporation of ATP-8-CI4 for the chemical work. Treatment of either N-AcGm or N-AcMm with into an HCIOe-insoluble, presumably polymeric fraction: Table I indicates that reaction 1 specifi- pyridine and nickelous acetate under the conditions cally requires the presence of ribonucleoside 5'- used for the degradation of NANA2 gave a mixture triphosphates either singly or in combination; if a of N-AcGm and N-AcMm (approximately 8:2) as more highly purified enzyme preparation, low in well as traces of unidentified components which endogenous RNA, is used the reaction becomes de- were apparent by paper chromatography, but were pendent on added S-RNA. Reaction 2 occurs not identified. Thus, 36 mg. of synthetic Nwith P P i but not with P i , and appears to favor S- AcMm,' 2 ml. of anhydrous pyridine, 0.12 g. of RNA over other polyribonucleotides. l 3 Table I1 nickelous acetate, heated a t 100' for 1.5 hr. yielded indicates that reaction (3) requires either the pres- 6 mg. of first crop crystalline material. The ence of a mixture of ribonucleoside triphosphates, crystals were identified as N-AcGm by: (1) m.p. (202-203', uncor., dec.; no depression on admix(10) E. Herbert, V. R . Potter and L. I. Hecht, J . B i d . Chem., 225, 059 (1957). ( 1 1) M . Edmonds and R . Abrams, Biochim. Biophys. Acta, 2 6 , 226 (1967). (12) K . S.Kirby, Biochcm. J . , 64,405 (1956). (13) ATP has been identified as a product in this reaction.
+
(1) D. G. Comb and S. Roseman, THIS JOURNAL, 80,497 (1958). (2) R. Kuhn and R. Brossmer, Chcm. Bn.,89,2471 (1956). (3) F. Zilliken and M. C.Glick, Nafurvissenschaffcn,43, 536 (1956). (4) J. W. Cornforth. M. E. Firth and A. Gottschalk, Biochem. J . , 68, 57 (1958).
