The Fourier synthesis of the crystal structure of strychnine sulphate pentahydrate

Bokhoven, C.; Schoone, J. C.; Bijvoet, J. M.

doi:10.1107/s0365110x51000891

Cited by 111 publications

(42 citation statements)

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“…In certain circumstances these relations may be useful however. The method of isomorphous replacement, as used by Bokhoven, Schoone & Bijvoet (1951), for example, gives phase angles with an inherent twofold ambiguity. If now the ambiguity is removed for some limited number of the larger unitary structure factors (by finding an approximate structure), these phases can be used to indicate which phase is correct for at least some of the remaining structure factors.…”

Section: Discussionmentioning

confidence: 99%

Relations between the phases of structure factors

Cochran¹

1955

Acta Cryst

185

128

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Section: Discussionmentioning

confidence: 99%

Relations between the phases of structure factors

Cochran¹

1955

Acta Cryst

185

128

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“…The optical rotation of this compound (aTO) was originally reported to be zero in acetone solvent but was subsequently determined to be (+) in hexane with a plane-positive optical rotatory dispersion curve (see footnote 35 and figure 1 Previous structure determinations on the absolute configuration of (-)-strychnine had produced conflicting results. The x-ray structure analysis was originally performed by Bokhoven et al (24) and by Robertson and Beevers (25,26). The former group (24) used the isomorphous replacement method with strychninium sulfate and strychninium selenate, whereas the latter group used strychnine hydrobromide dihydrate.…”

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confidence: 99%

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

Yuan

Stevens

Bau

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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The absolute configuration of (+)-neopentyl-1-d alcohol, prepared by the reduction of 2,2-dimethylpropanal-l-d by actively fermenting yeast, has been determined to be S by neutron diffraction. The neutron study was carried out on the phthalate half ester of neopentyl-l-d alcohol, crystallized as its strychnine salt. The absolute configuration ofthe (-)-strychninium cation was first determined by an x-ray anomalous dispersion study of its iodide salt. The chiral skeleton of strychnine then served as a reference from which the absolute configuration of the -O-CHD-C(CH3)3 group of neopentyl phthalate was determined. Difference Fourier maps calculated from the neutron data showed unambiguously that the -0-CHD-C(CH3)3 groups of both independent molecules in the unit cell had the S configuration. This work proves conclusively that the yeast system reduces aldehydes by delivering hydrogen to the re face of the carbonyl group. The enzymatic reduction of an aldehyde to an alcohol is an important example of a stereospecific biological process that has been studied extensively (1). It is a prototype reaction for many biochemically significant transformations involving the coenzyme NADH. In addition, optically active deuterated alcohols of the type R-CHD-OH have been of great importance in the elucidation of the stereochemistry of displacement reactions at primary carbons (1).The stereospecificity of enzymatic acetaldehyde reduction and ethanol oxidation was established (2-4) when it was discovered that reduction of acetaldehyde-1-d with NADH and yeast alcohol dehydrogenase (ADH) gave ethanol-1-d, which, upon enzymatic reoxidation, returned only acetaldehyde-1-d without loss of deuterium (Scheme I): chemistries were identical. Although neopentyl-1-d and benzyl-1-d alcohols have not been produced by reductions using purified NADH and yeast ADH, it is firmly believed that the NADH/yeast ADH system is responsible for those reductions in the actively fermenting yeast system. The structure ofhorse liver ADH, which is closely related to yeast ADH, has been determined to 2.4-A resolution by x-ray diffraction techniques (9)(10)(11)(12)(13)(14). A model of the active site has been proposed in which the oxygen atom of the substrate binds directly to the zinc atom, which fixes the orientation of the substrate with respect to the coenzyme and controls the stereospecificity of the reaction (14). In this mechanism, direct hydrogen transfer from NADH to substrate is believed to take place.For the most part, the absolute configurations of deuterated alcohols (R-CHD-OH) have been determined by comparison ofNMR and polarimetry data with related molecules ofknown stereochemistry (15, 16). For example, the absolute configuration of ethanol-1-d has been deduced by correlation with a pyranose sugar whose configuration at the CHD center was established by NMR (17) and by correlation with 2-butanol-2-d (18) and pentane-2-d (19) of known configuration. In addition, the absolute configuration of glycolic-d acid, determined by neutron diffrac...

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“…In phase determination of non-centrosymmetric reflexions the conventional isomorphous replacement method leads to an ambiguous result for the phase angle (Bokhoven, Schoone & Bijvoet, 1951). However, by including anomalous scattering information in the phase determination, this ambiguity may be resolved and a unique determination made (Ramachandran & Raman, 1956).…”

Section: (B) Difference Fourier Synthesesmentioning

confidence: 99%

The determination of the position of anomalously scattering heavy atom groups in protein crystals

Matthews¹

1966

Acta Cryst

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Methods are proposed by which isomorphous replacement and anomalous scattering measurements may be combined to locate anomalously scattering heavy atoms in protein structures. Both Patterson and Fourier methods are discussed and examples are given to illustrate the use of new methods.The examples show how the relative coordinates of heavy atom groups in different derivatives may be determined, and how the absolute configuration of these coordinates may be established.

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The Fourier synthesis of the crystal structure of strychnine sulphate pentahydrate

Cited by 111 publications

References 1 publication

Relations between the phases of structure factors

Relations between the phases of structure factors

Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.

The determination of the position of anomalously scattering heavy atom groups in protein crystals

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