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 t o 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 t h a t 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. I n 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
