Tha work dam Wing the g~lrlod January hst, 1991 to

January Ut, l')Slr has been de8crib.d In a series of pubIAaatianr
which were prosentced With laart year's report.

to theso Is appebrrd.6.

ha8 114v been sent to PrOaBa
#on g',,nctian ?f Dssoxyxcibosa Buc18ib AoId%
paper ha8 been described la previous repw%;s,

A list of referenass

One ilhrthar publiclation an the saso rmb38ot

The title IS "The 3-Dlmensionrl Patter-

           The content of this

The experisnee of other8 who have stubfd the Patterson

-4-

funations of la~ge molemaless and In garticular of psotsins, show8
that great caution must be exwclaed in rattempting an interprets-

tlon.
function af rsuoh a caraplex moleculs It is moat probable that
impartant fet.&urB)s of the strncture are entirely obscured, and

others dlrtortd.  ESeverthelsrsa, two features of' F*fg* 2 appear
to worthy of attention.

In the present case) %n tb oylindrically averaged Pattarsan

Tha scaries of peaks Indicated by crossea in pig, 2a auggeatac

an end-on viev of 8 double layer of rods of dfametm 11 A.
la cronsistent with Gatron's tentatfve suggestinn that each turn
of the helix contains a double layer of p(: -helices lying perpen-
diauLar to the axlr of the virus partiale.  The linearity of the
aeries of Patterson psakls indicates #Et the 11 A dlapaeter rods
lie in a tangential rather w.rrtlJ1 a radial direction with reppect
to the partiale axlr (rig. 3).

This

The PS&~ ljrt

lW-lfi0 A in qge 2b UOhCideS With the knom

dituwter of t;ha partiale,.
the bsrere llns and at the pitch height and bulging sytxne?triaallp on
either aide, am best bo explainad by supposing that the partlule
b8 an ertametlglroave, the groove folLavSng the line of the helix.
72;lrther tavldence, nf meh Q groove is given b%law.

The sficaga of this peals 4th p~akar an

Since the mmber ai' units on the helix in each repetat perid

in the axlal biractlon is large (probably 371, the projection of
the structure on a plane pergerailiculwr' to the nxir of the vim$
particle ies virtually ~entro-ayrmastria~

The strong periodictlty of

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intensity over a oans1der:ble region aP the a::uation, and the elor.

rarmblanae betmen the centra maxfsa artd thoro -oh wcvuld be

given by stmc3tmalesr rQdr ai the stme dhmstsr, together make It
poslrlble to deterdm the 6lgm of the first 12 equatorial maXiu.
Hem e, with the aid ab B strong %rtiflcIal teaper&u!e factorn
to elbinate the effect of diffracttion at larger angles, the Flrrtirier
proJectlon of the vim8 was rralaulsted.

The moat rtsiking feature of the Paurier gro3eetion is &

                           One possible

rhell of high density at a radius of abaut 55 A.

explanation of -1s is tbat thrs vim8 RM lies in this shsll.
natively, the high density my simply oarresmrt to a shell of Inw

hydsation.

Altar-

Zt is not, in gerur4, possible to attsimte certain parts

of an X-ray diagram to pestloular features ai tha diffracting struo-

?are.  However, in the case of halfoal atruc:\lres, anae the helioaA

pisrra~aeters have been eatabliahed there are eertaiir restriction8 on

-7-

building unit of the helix mmshta of two chemically equivalent

surface, may perhaps accmt for the surprising variety and extant of

the chemical modificzttimr which is possible to make in tobaoeo moralo

virus without braraking up the particle, and, in BOW cattea, rfthcmt

destroyiq it8 IILfeCtIVitYo

There Is thus reason to hope that htrther chemicfil work on

the accessibility of the, different Ezalno-acids together with X-ray

studies of :-he oh@mically mociificsd forms inay help to tlucidate not

only the configurations of the pmtein chains, but also the positions

of oertain amino acids in the vintes.

cerned vlth PBS~:~PC~ on ood and carbon, bath In unfve~sitiea and in

industrial organi sstlons.

fig. 1. X-ray diagram aP TMY gel. Orientated rporriren obtsiinnd

from H.W, Plrleb preparation of TMV, Rothamated

Culture, lmbnted With prat*alptio

pig. 3. Schamtict representation of proposed arrangement of

protein Sn TMB. S3.B. This drawbg Is inserted for
the aake of alarlty;
over-simplification, as vel1 as the insertion of
detail ach is of no quantitative signiflaa~ncre.

it Inevitably involve8 great

a) Vlew of a short length of virus partlcrlo showing

wlits aad subdts on 6 turns of the helix.

b) Axial seatlan of a short length of Vprus particle.

Shaded reg.ion represents RNA,