Dr. DeWitt Statten, a,, lQLulDD
Through: Dr. Leon A. Heppel, LBM

Dr. Maxine F. Singer

Dr. G. Cilbsrt Ashwsll, LBM

Map 4, 1960

Scientific Accmplisbts Report

Genetic and biochedcal data indicate that the pnes, the carriers of

hereditary information, are cc#possd of dtoxyribosenuclefc acid (XIHA).
relation between opecific genes end spee1fi.a protei- has been demonstrated Ln
euany laboratories.  Thus, in any orgmfsm, the presence of a giwen great will be
erpreewd by the lrynthesfs of a particular protein of definite atructute (i.e,,
linear arraagernent of .Blins acidpi).
array of ~~leotide units Ln DNA reflects a code which directs the
sequencer of am€m acids in the related protein.
gert that thia transfer of informatinn f~a DNA to protein 26 mediated by a
third rpatsrial, nmly, rihsclrtwleic ocLd (RNA).

The

Zt Is generally believed that the linear

Various experiments also mg-

Withur the precise sechanfsm of proteLn biospthesis nor the sgcscific

role of RiUA in that protsss has been definitively described.  bwewr, it is
widely believed that the first steps in thar process are 1) &he activation of
duo acids by specific tat]leaer and 2) the eaeymalc€cally catalyzed traaefer of
the mino acids to RNA. These two resctions have been described. The RNA found
in eofution In tk cell sap fmsctioas in this way and there is evidence that
dLstfnct BNA chains (transfer RNA) est for the different mino acids.
it ia belfeved that the sequence of nrrc1atotid-e units in a particular trausfer
BPJA chain detarPiraets that chain's specificity for a given aarirao acid.

Further,

During the past year, in ciollaboration with Dr. Giulio L. Cantonf of the

As a result of these studies several interesting and signfficant features

National tnstitrtte of Mental Health, we studied the stxucture of the transfer
IWA.
of tb transfer Bu3A hawe been elucidated.
of transfer RNA containing chain8 upecific for a variety of amino aCfd8.
general structure of RNA may be written pHpWpNpW.... .p#pyJp# (wbre I represents
Purim or pyrimidine ribonucleosides and p represents ptsosphatc groups).
chain length studies and analysis tn the ultracentrifuge indicate that the ausrbet
af N moietfes in transfer RNA is about 100.
RNA molecules in the mixture hdwc the satme nucleotide dit tbe left-hand end of the
chain (ae written above) and that this residue is S'-@sauyIlc acid.  Similarly,
the extreme ri&t-hsnd eide of the chain wk~ fouslzd to be either adenosine or
cytidine. Tlgse latter findings are consistent vfth work in several other
laboratoriele & Indicates that 8 terminal. ....-PA sequence is required for
transfer RHA to bind dno acids (C and A stand for cytidine and adeaosiua
moeitiss, respectively).  Tbe same reqwnca bids for all the mino acids,
we may write a saersvtiat more specific structure for transfer WBA, namely pGpNpRpN
.....p EJpCpCpA.

The work was carried out on samples

Th6

Chemical

We be found that all the transfer

Thus

It is of intereat that the two ends of a11 tha! chins are tb samt.

-2-

the can conclude from these ffhdiws that the opeclficicy of a particular transfer
RMA €or a given atadgo acid =st be determined smre In tb internal purrion of
the chain,

Several interesting facts were found when the total nucleotide content of

Cke transfer RNA -8 detbcrmlaecl.
tlra follawlng relatitre mnouutc%:
acid, 31, cytidylic acid, 29, and 5-rlbesylurscil riaonophosphata, 3.
8319h fs thus eharactarfzed by I very high contant oE tk recently discovered nucleo-
tide, S-r%bosyluracil Paonopbspharte.
mtwimtri OE this colapouzld.  Thtr 8ifgnfficance of tb high quantity of 5-ribesyluxscll
in transfer RNA is, at prtracnt, mb.
opuivaleacer of adenylic amd uridylic acid on osio hand, and cgtldylic and gugnylic
acid on tBe other. Total cellular RWA does not ih this salatlon. DNA does,
hawaver, hewt a simflar equivalence of nucleoeidee e& this lad us to Lnvesltlgare
the. poseibtlity that transfer R&iA be 8 hy&rogen-bontled double-hslfcsl secondary
structure tsimflar to tbt ~f TMA.  Zn tbsa aJrparfPPEsnts we studied the reactivity
of transfer RNA la specific chemical and enzymatic procaduras.
certain tentative conclusions concerning the secondary structure of the EWA.
tillthough WQS do not believe that cb sccandary stmetare of transfer RNA is Ilvia
that of DUQ., regions of iatenaolecu%ar or intrcr;8saloc=ular hydrogen boadin8 probably
stxist.

Tbs five main nucleotide, residues are present in

Adenylic acid, 17, uridylfo acid, 17, guanylic

"he transfer

Ocher types of RNB barn ialmost negligible

A SCICOQ~ point; of interest is the near

The results permit

Thus,

We are am fnvrrrtigating this hypotbsfrr further,

MFS : wca