STRUCTURE OF POLYGLYCINE II

By DIL F. H. c. CRlCt
Da. ALEX&k RICH@

The StNOtUW5 WB PTOpOdB 63
simple. All the polypeptide oh8inm
~plU'dh~eadeeohOllehM8
threefoldtxwewaxia. Thecheinsere
lJ=-~~~-w,~
chain lleiug hytkgen-hollded to
e8ohofitfJl3ixlK@&oum. These
hyQogenbondsllerot@lyperpen-

dlreotionsandnotmerelyinone
dire&ion 88 in a iSsta-uf3ture. This
CsnkiweninFig. 1,whiehiee

Another view of t&4 structure
bEhOWIliIlFig.2. ThieiSepro-
jection along the s-&a and perpen-
dioul8rtolihemrewaxia(thsr~),
which NM wrtidy, The4 eeaieetl
W8~tO-thOOtNOtMObtO
look8toneofther&due68tthe
bottomoft&eflgure. Thi8lhnm
that the planer peptide group ia
illdhl0d 8t 8bOUt 26' to t&J flbl'9
de, and has ita plane perpen-

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NO, 4406  October 22 1955

NATURE

of one awymmetrio unit (excepting hydrogeu atoms)
amgiveninTablel,tothemsmtO-OIA.

2.78 A, whioh in e little ahort, but quite moeptabw.
ThehydrogenbondQalmetmtrai&t,aeoenbe
menfrom-w-All-.byurder Warlr4t-
tmmeareaooept&le,sndinGofispaoe-flllingmodela
show that the ohains paok @@her in 8 comfortable
manner.
Sinoe there in no IMQWUII&~~O carbon atom in poly-
giycim, the mirror itnttge struuture (opeoe group
P3,) ie eqtutlly pwriile.

We have calmlaw fhe spacings and intmaitiee
expeutedfromthilJt3tmtlm fdr all redexiona out to
1*8k Dr.C.aBlunfordandhilJ~lleagueehave
kindly shown ua the originml of the powder photo-
graph (their Fig. 1). Their X-ray data ore in good
qu3litative agreement with our cabulationa The
wry otrong 4*16A. reflexion L 1010, A @we at
Fig. 1 &own that thin will be i&mm. The 3*1-A.
reflexion has e amall ooatributioa fium 0008, but imp
meetly due to 1012, epaaing 5~0% A The &mmgtb

the pxwent qmlit&m Jtgnmlmtwiththem-,
memtale&ieumemnkmit~oertainthstthe
etrwttwofpol~inelxiaofthiageuttwlfypa
Tb&enableetprtooomlu~th&onlypoly&mine
canfo?mEmohelattice+themLnoroomfor6ide-
ohaiminthelattioermlwmmeofthehydrogen
..m.ere broken.
          -.--. I
WeJl8BllOCJplUd remo2i*~ysdn@epdy&miw
ohftinahouldtltkeupthbplwbecionugtwti~;
thiaimpremnnablydi&&idbytheiutera&~
between neighbouring obaism, whioh im
exmt three-foldmew&. We note wi t!r-
                         intmmt
th8t polyprolim* the lMuotmw OfWhiOhberllboeol
            hi%
bemreportedbyCowanandlKoGIevin',andw'
iSlUltLbbtOfOrm~bCN2lb,~~8rimilu
baokbone~~