Structure of <i>tert</i>-butyloxycarbonyl-L-alanyl-L-proline monohydrate (<i>t</i>-Boc-Ala-Pro)

Kamwaya, M. E.; Oster, O.; Bradaczek, H.; Ponnuswamy, M. N.; Parthasarathy, S.; Nagaraj, Ramakrishnan; Balaram, P.

doi:10.1107/s0567740882002313

Cited by 11 publications

(1 citation statement)

References 23 publications

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“…In many publications it is possible that lack of familiarity with English has led to confusing statements; thus Kamwaya et al (1982) seem to indicate that the correct absolute configuration had a worse R than the false one, while Nasini, Merlini, Andreeti, Bocelli & Sgarabotto (1982) seem to have compared refinement of the same absolute configuration for two data sets. Yamada et al (1982) seem to have established an absolute configuration opposite to the one refined, yet not to have repeated the refinement with the new configuration; it is thus not clear whether the tables correspond to the correct enantiomer.…”

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confidence: 99%

The determination of absolute structure. II. Absolute configurations from the Cambridge Crystallographic Data Centre files for 1982

Jones¹

1984

Acta Crystallogr A Found Crystallogr

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A survey of 102 structures flagged with 'absolute configuration' in the Cambridge Crystallographic Data Centre files for 1982 reveals many unsatisfactory features in the original publications. These are associated with data collection (lack of Friedel opposites and of absorption corrections), misinterpretation of the term 'absolute configuration' (claimed for achiral molecules and space groups), methods used to determine absolute configuration (over-optimistic interpretation of discriminatory tests) and presentation of results (little experimental detail, no prominent statement that an absolute configuration was assigned, no clear description of the methods used). Some confusion arises because of unintentional flagging of absolute configurations determined by solely chemical means.would today be either obviously correct or, in suspicious cases, easy to check. It therefore seemed worth while to inspect more recent reports of absolute structures to see if the situation had improved. This paper reviews such reports from the year 1982.

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Section: Use Of Englishmentioning

confidence: 99%

The determination of absolute structure. II. Absolute configurations from the Cambridge Crystallographic Data Centre files for 1982

Jones¹

1984

Acta Crystallogr A Found Crystallogr

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Crystal Structure and Conformation of Short Linear Peptides: Part VI: L‐Alanyl‐L‐Prolyl‐Glycine Monohydrate

Declercq

Tinant

et al. 1987

Bulletin des Soc Chimique

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C10H1,NIOr.H20, H r -261.28, orthorhybic, P212121, a -6.716;1), b = 11.780(1), c -16.248(?)1, Y -1285.6(2)1 , 2 = 4, Dr -1.35 g.cm' , CuKo, A -1.5418 A, u -9.28 cm-, P ( 0 0 0 ) -560, T 291K, R -0.063 for 2447 observed reflections. The molecule (hereafter APG) adop:s a collagen-like conformation at Pro residue with ( 0 2 , $12) values of (-66.6 , 156.9') and an extended form at the two terminal residues. The pyrrolidine ring is disordered with two positions for C(6) : its conformation is C2-CY-ondo for the major component(75%) end C2-Cy-eto for the minor one(250). The geometry and the main-chain conformation are both in excellent agreement with those found in the tripeptide L-Leu-L-Pro-Gly monohydrate (hereafter LPG) It seems that the atoms further than Cy of the Leu side chain do not affect significantly the conformation of peptide backbone in this case. The twofold screw axis in the LPG crystal structure corresponds to that of the APG in the a direction.

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Calibration of effective van der Waals atomic contact radii for proteins and peptides

1987

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Effective van der Waals radii were calibrated in such a way that molecular models built from standard bond lengths and bond angles reproduced the amino acid conformations observed by crystallography in proteins and peptides. The calibrations were based on the comparison of the Ramachandran plots prepared from high-resolution X-ray data of proteins and peptides with the allowed phi, psi torsional angle space for the dipeptide molecular models. The calibrated radii are useful as criteria with which to filter energetically improbable conformations in molecular modeling studies of proteins and peptides.

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Structure of tert-butyloxycarbonyl-L-alanyl-L-proline monohydrate (t-Boc-Ala-Pro)

Cited by 11 publications

References 23 publications

The determination of absolute structure. II. Absolute configurations from the Cambridge Crystallographic Data Centre files for 1982

The determination of absolute structure. II. Absolute configurations from the Cambridge Crystallographic Data Centre files for 1982

Crystal Structure and Conformation of Short Linear Peptides: Part VI: L‐Alanyl‐L‐Prolyl‐Glycine Monohydrate

Calibration of effective van der Waals atomic contact radii for proteins and peptides

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