organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
6-O-adenyltransferase. It could be a good starting compound
for the design of more efficient ‘decoy acceptors’ of amino-
glycoside-modifying enzymes (Latorre et al., 2007). Strepti-
dine is a metabolite but not the antibiotic itself. It is a potential
contributor to ototoxicity after prolonged antibiotic adminis-
tration since it acts as a damaging agent for the inner ear
(Meza & Granados, 2005). The only previous structural study
of this compound employed X-ray powder diffraction (Rose,
1954). We report here a single-crystal study of the title
compound, (I) (Fig. 1), at 100 K.
ISSN 0108-2701
Streptidinium sulfate monohydrate
a
b
b
´
Barbara Lesniewska, Said Jebors, Anthony W. Coleman
a
´
and Kinga Suwinska *
The sulfate anions of (I) are doubly charged but the water
molecule is not protonated. The stoichoimetry of the crystal
structure requires the streptidinium cation to carry two posi-
tive charges, which are located on the guanidine groups. The
planarity of these groups and their relative closeness to the
sulfate anions suggest that they must in fact be protonated.
The sulfate anion is disordered over two sets of atomic sites,
with occupancies of 0.786 (3) and 0.214 (3).
aInstitute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52,
b
´
PL-01 224 Warsaw, Poland, and Institut de Biologie et Chimie des Proteines, UMR
´
5086, CNRS, Universite Lyon 1, 7 Passage du Vercors, F69367 Lyon, France
Correspondence e-mail: kinga@ichf.edu.pl
Received 16 March 2009
Accepted 27 April 2009
Online 2 May 2009
The central cyclohexane ring adopts a classical chair
conformation. All H atoms occupy axial positions, while
hydroxyl groups and protonated guanidine groups occupy
equatorial positions. Streptidine is present in a cationic form
and the protonation is on the C NH N atom in both guani-
dine fragments. The same type of protonation was found in the
crystal structure of streptomycin oxime selenate tetrahydrate
(Neidle et al., 1978). From this result, the protonation on the
C—NH2 group of streptidine, as proposed by Latorre et al.
(2007), seems to be incorrect.
In streptidinium sulfate monohydrate {systematic name: 1,10-
[(1S,3R,4S,6R)-2,4,5,6-tetrahydroxycyclohexane-1,3-diyl]di-
2+
guanidinium sulfate monohydrate}, C8H20N6O4 ꢀSO42ꢁꢀH2O,
at 100 (2) K, the components are arranged in double helices
based on hydrogen bonds. One helix contains streptidinium
cations and the other contains disordered sulfate anions and
solvent water molecules. The helices are linked into a three-
dimensional hydrogen-bonded network by O—Hꢀ ꢀ ꢀO and
N—Hꢀ ꢀ ꢀO hydrogen bonds.
In both guanidinium groups, the N atoms have a planar
geometry. The C—N bond lengths are in the range 1.318 (5)–
Comment
˚
1.355 (5) A, intermediate between double (1.28 A; Interna-
˚
Streptidine {N,N000-[(1S,3R,4S,6R)-2,4,5,6-tetrahydroxycyclo-
hexane-1,3-diyl]diguanidine} is a substrate in the biosynthesis
of aminoglycosides as streptomycin, dihydrostreptomycin and
bluensomycin. Streptidine is a derivative of cyclohexane which
is substituted with four hydroxyl groups and two basic
guanidine groups, and it has been shown to be one of the eight
meso forms of 1,3-diguanido-2,4,5,6-tetrahydroxycyclohexane
(Carter et al., 1947). Streptidine is responsible for the Saka-
guchi reaction given by streptomycin, whereby guanidines in
alkaline solution develop an intense red colour when treated
with ꢀ-naphthol and sodium hypochlorite; this is a qualitative
test for arginine, whether free or combined within a protein.
Electrometric titration of streptidine dihydrochloride showed
it to be a very strong base (Fried et al., 1946).
tional Tables for Crystallography, 1999, Vol. C) and single
˚
(1.47 A) bonds, indicating delocalization of the double C
N
bond over all three C—N bonds. The guanidinium groups, N1–
Figure 1
The molecular structure of (I), showing the atom-labelling scheme. Only
the major component of the sulfate anion is shown. Displacement
ellipsoids are drawn at the 50% probability level and H atoms are shown
as small spheres of arbitrary radii.
Streptidine is a ‘decoy acceptor’ which allows the antibiotic
activity of streptomycin to recover against the Escherichia coli
strain overexpressing the aminoglycoside-modifying enzyme
o290 # 2009 International Union of Crystallography
doi:10.1107/S0108270109015650
Acta Cryst. (2009). C65, o290–o292