ZIB

1

Digitale Medien

Packing interactions of crystallographically independent molecules in organic crystals (1993)

Karthe, P. ; Sadasivan, C. ; Gautham, N.

Copenhagen : International Union of Crystallography (IUCr)

Acta crystallographica 49 (1993), S. 1069-1071

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ISSN: 1600-5740

Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001

Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1107/S0108768193004410

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2

Digitale Medien

Space-group degeneracy in the packing of a non-selfcomplementary Z-DNA hexamer (1994)

Sadasivan, C. ; Karthe, P. ; Gautham, N.

Copenhagen : International Union of Crystallography (IUCr)

Acta crystallographica 50 (1994), S. 192-196

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ISSN: 1399-0047

Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001

Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik

Notizen: The X-ray diffraction pattern of the crystals of the non-selfcomplementary hexadeoxyribonucleotide d(CGCACG)·d(CGTGCG) can be indexed in four different space groups: (i) P65 and P21, with cell parameters a = 17.75 (1), b = 17.76 (1), c = 42.77 (3) Å, α = 90, β = 90, γ = 120°, and (ii) P212121 and C2, with cell parameters a = 17.75 (1), b = 30.74 (2), c = 42.77 (3) Å, α = 90, β = 90, γ = 90°. While the Rmerge for the equivalent reflections in the different space groups indicates that P21 is the correct choice in the present case, it is demonstrated that the near degeneracy of the space groups arises out of the fact that the DNA molecule is nearly cylindrical. A perfect cylinder would show perfect degeneracy.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1107/S0907444993011035

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3

Digitale Medien

Plasticity, Hydration and Accessibility in Ribonuclease A. The Structure of a New Crystal Form and its Low-Humidity Variant (1998)

Sadasivan, C. ; Nagendra, H. G. ; Vijayan, M.

Copenhagen : International Union of Crystallography (IUCr)

Acta crystallographica 54 (1998), S. 1343-1352

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ISSN: 1399-0047

Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001

Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik

Notizen: The structures of a new crystal form of ribonuclease A and its low-humidity variant, each containing two crystallographically independent molecules, have been determined and refined. A detailed comparison of these structures with those of the other known crystal forms of the enzyme, which have different packing arrangements and solvent composition, leads to a meaningful delineation of the rigid and flexible regions of the protein molecule and the nature of its plasticity. Many of the water molecules which are common to all the structures are involved in bridging different regions of the protein molecule, thus emphasizing the role of water in stabilizing the tertiary structure. The analysis of the structures shows that for a given N or O atom, the level of hydration increases with accessible surface area, but levels off at an area of about 10 Å2. Generally, the hydration level tends to drop when the area increases beyond about 20 Å2. This drop correlates with an increase in the displacement parameter. The analysis also suggests that the van der Waals radii and probe radius normally used in accessible surface area calculations are not appropriate for dealing with all situations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1107/S0907444998005149

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4

Digitale Medien

Molecular structure and activity of Vicolides isolated fromVicoa indica (1993)

Sadasivan, C. ; Pattabhi, Vasantha ; Gautham, N. ; [weitere]

Springer

Journal of chemical crystallography 23 (1993), S. 339-344

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ISSN: 1572-8854

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: Abstract Vicolide A to D, sesquiterpenoid lactones, were isolated from “Vicoa indica” and crystal structure of A and D were established by X-ray analysis. The structures were solved by direct methods and refined to an R index of 0.09. Vicolide B and D are reported to have anti-fertility activity while A and C are devoid of this activity. Conformational features of B and C are similar but differ from those of A and C.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01263596

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5

Digitale Medien

Molecular structure of Lantadene-B&C, triterpenoids ofantana camara, red variety: Lantadene-B, 22β-angeloyloxy-3-oxoolean-12-en-28-oic acid; Lantadene-C, 22 β-(S)-2′-methyl butanoyloxy-3-oxoolean-12-en-28-oic acid (1993)

Nethaji, M. ; Rufes, C. ; Sadasivan, C. ; [weitere]

Springer

Journal of chemical crystallography 23 (1993), S. 469-472

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ISSN: 1572-8854

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: Abstract (I)Lantadene-B: C35H52O5,M r =552.80, MonoclinicC2,a=25.65(1),b=6.819(9),c=18.75(1) Å,β=100.61(9),V=3223(5) Å3,Z=4,D x =1.14 g cm−3 CuKα (λ=1.5418A),μ=5.5 cm−1,F(000)=1208,R=0.118,wR=0.132 for 1527 observed reflections withF o ≥2σ(F o ). (II)Lantadene-C: C35H54O5·CH3OH,Mr=586.85, Monoclinic,P21,a=9.822(3),b=10.909(3),c=16.120(8)Å,β=99.82(4),V=1702(1)Å3,Z=2,D x =1.145 g cm−3, MoKα (λ=0.7107Å), μ=0.708 cm−1 F(000)=644,R=0.098, wR=0.094 for 1073 observed reflections. The rings A, B, C, D, and E aretrans, trans, trans, cis fused and are in chair, chair, sofa, half-chair, chair conformations, respectively, in both the structures. In the unit cell the molecules are stabilized by O-H⋯O hydrogen bonds in both the structures, however an additional C-H⋯O interaction is observed in the case of Lantadene-C.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01182520

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