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Introduction of Cystine Bridges into Collagen.

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The infrared spectrum shows two typical NH2 vibrational bands at 3495
and 3380 cni I and a C-C vibrational band at 1641 cm-1, which are not
i l l the spectrum OF the starting material, and the C s N band at 2186 cm.-I
is about 5 0 cm-1 lower than that in the starting material owing to
conjugation of the C E N group with the C-C group. The substance
evolves 1.04 mole Nz with HN02, in agreement with formula ( 2 ) , which
contains a primary amino group.
Adipodinitrile gave 2-amino-I-cyanocyclopent-I-ene by the method of
7 I i o n i p ~ v n[ I ] using sodium t-butoxide as condensing agent. In the same
manner. ( 2 ) can also be obtained from piperidinoacetonitrile. This
conlirms that ( 2 ) contains the same enaminonitrile grouping
N C C C NH2 as does 2-amino-I-cyanocyclopent-I-ene( 3 ) .
This new course of reaction seems to be of general importance. I t can be attributed to the bulky nature of the organic
component in t-butylmagnesium chloride, for n-butylmagnesium chloride and piperidinoacetonitrile d o not yield
the dimer, the Grignard reagent adding o n normally to give
n-butyl piperidinomethylketone in 64 "/, yield.
N C11:
Received, October 8th. 1962
[ Z 382/205 IEI
[ I1 Q . E. Thoinpsun, J. Amer. chem. SOC.80, 5485 (1958).
Condensation Reactions with Monochlorinated
By Dr. M.Wieber and Prof. Dr. M . Schmidt
lnstitut fur Anorganische Chemie
der Universitiit Marburg/Lahn (Germany)
Mixtures of chloromethyl-methylpolysiloxanes have already
been prepared by equilibrating cyclic dimethylpolysiloxanes
with chloromethyldimethylchlorosilane[l].
The availability of chloromethyldimethylsilanol (1) - synthetired by hydrolysis of 1,3-bischlorometbyltetramethylCH,
n $'=
6 ' C ; b.p. 47 "C/5 nim;
1.4402; d&
Introduction of Cystine Bridges into Collagen I*]
By Dr. F. Schade and Prof. Dr. H. Zahn
Deutsches Wollforschungsinstitut
an der Technischen Hochschule Aachen (Germany)
Nitrophenyl esters are generally suitable for introducing
mono- and poly-functional carboxylic acids into proteins
such as insulin, wool keratin, silk fibroin, and collagen [I].
We have been able to build authentic cystine bridges into
tendon collagen by treating it with the bis-(o-nitrophenyl
ester) of bis(carbobenzyloxy)cystine, to the extent of 5.5 or
1 1 millimoles of disulfide groups per gram of collagen. A
bifunctional reaction of the bis(nitropheny1 ester) is indicated
by the raising of the transition temperature (shrinking
temperature) from 64 "C (control experiment) to 69 "C, and
by the clear relationship between the transition temperature
and the number of disulfide groups during reduction and reoxidation: reduction with thioglycolic acid splits the disulfide
links and lowers the transition temperature,while re-oxidation
with air raises both the disulfide content and the transition
temperature. lrreversible destruction of the disulfide groups
by oxidation with performic acid lowered the transition
temperature. This lends support to the cross-linking theory
of tanning 121.
Experimental: 1 g of tendon collagen [3] was treated with a
solution of 0.5 g of the bis-(o-nitrophenyl ester) of bis(carbobenzy1oxy)cystine (made from bis(carbobenzy1oxy)cystine and o-nitrophenol with dicyclohexyl carbodiimide,
m.p. 125-126 "C) in 200 ml of dimethylformamide and 40 ml
of water for 100 hours at 20°C. The product was washed
with dimethylformamide. Excess bis(nitropheny1 ester) and
salt-like derivatives were removed by extraction at room
temperature with ether for 60 hours and with 0.1 N ammonia
for 24 hours. The disulfide content was estimated by the
method of Zahn and Traumann [4]. The disulfide bonds were
reduced with 1 N thioglycolic acid (distilled) adjusted to
p H 9.2 with ammonia for 4 hours at 20°C. Thiol group
analysis was carried out according to Zuhn, Gertksen, and
Meichelbeck [5]; performic acid oxidation of disulfide groups
was performed by the method of T/iompson [6]; shrinkage
temperature estimations were made according to Zahn and
Wegerle 171.
Received, October 15th, 1962
disilazane which has recently been prepared [2] -- enabled us
to prepare definite members of this series in quantitative
Thus, compound I reacts with dimethyldichlorosilane in
ether i n the presence of stoichiometric quantities of triethylamine to form 1,5-bischloromethyl-hexamethyltrisiloxane
(b.p. 109 'C/lO mm, nfy = 1.4304, d& = 1.023).
CICH2Si-0 -Si--O-Ai-CH2CI
+ 2[HN(C*H&]CI
Chlorosiloxanes form higher homologues correspondingly.
Compound I reacts in the same manner with dimethyldichlorogermane, giving germanosiloxane.
[Z 372/200 I € ]
[*] Communication No. 6 on collagen; communication No. 5 :
H. Zahn, F. Growitz, and G . C. yon Hey/, Kolloid-2. 180, 26
[l] F. Schade, Ph. D. thesis, Aachen 1962; reported briefly by
KI. Ziegler at the Informal Discussion on Fibrous Proteins and
Related Peptides of the Faraday Society on May 29th, 1962 in
Maidenhead, England.
121 See K . H . Gutstavson: The Chemistry and Reactivity of Collagen. Academic Press, New York 1956; W. Grassman, Das Leder
12, 165 (1961).
[3] Kindly supplied by the firm C. Freudenberg, WeinheimiBergstr., Germany.
[4] H.Zahn and K . Traumann, Melliand Textilber. 35,1069 (1954).
[5] H. Zahn, T. Gerthsen, and H. Meichelbeck, Melliand Textilber. 43, 1179 (1962).
[6] E. 0. P. Thompson, Aust. J. biol. Sci. 12, 282,490 (1959).
[7] H. Zahn and D . Wegerle, Kolloid-Z. 172, 30 (1960).
C'I CH2 SI 0 G e 0 S I - C H , -CI
(b p 95-98 "C/2 mm ,
The System Potassium AmideIAmmonia
By Prof. Dr. P.W. Schenk and cand. chem. H.Tulhoff
The use of dimethyldichlorostannane does not lead to the
corresponding stannosiloxane but to condensation of I to
I ,3-bischloromethyl-tetramethyldisiloxane.
Received October 8th, 1962
[Z 366/195 IE]
[ I ] J . L. Sparer, J . Amer. chem. SOC.71,273 (1949).
[2] M . Schtniclf and M . Wieber, Inorg. Chem., I , 909 (1962),
itrtcrrrtrt. Edit.
I (1962) 1 No. I2
lnstitut fur Anorganische Chemie
der Freien Universitiit Berlin (Germany)
Only few data are available on the solubilities of alkali metal
amides in liquid ammonia. According to Kraus [I],KN Hz is
more soluble than NaNH2, and Franklin [2] reports that a
saturated solution of KNH2 at -33.5 "C contains 45 g of
66 1
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introduction, cystine, bridge, collagen
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