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C M Weeks

Publications and source records attributed to C M Weeks.

44 records · Page 3Linked to original sources
PubMed1976

Conformational influence of a 19-methyl substituent in 19-oxygenated steroid structures.

The crystal and molecular structure of (19R)-19-methyl-5-androstene-3beta, 17beta, 19-triol (C20H32O3) has been determined. The crystals are orthorhombic and the space group is P212121. The unit cell parameters are a =11.179 A, b = 21.485 A, and c = 7.328 A. The structure was solved using the direct methods program MULTAN and refined anisotorpically to an R of 7.2% for all data. The methyl substituent on C(19) is located over the B ring and the hydroxyl between the A and C rings. The flexible B ring has a distorted half-chair conformation. The 19R configuration suggests that the reaction mechanism for the formation of this compound proposed by Wicha and Caspi is incorrect. Furthermore, these results indicate that the stereochemical assignment of C(19) by Skinner and Akhtar resulting from a tritiated sodium borohydride reduction is also suspect.

Androstenols↗
PubMed1975

Deoxycorticosterone-adenine interactions in a crystalline complex.

Deoxycorticosterone-adenine monohydrate is the first complex involving a steroid and a component of DNA to be successfully crystallized and studied by single crystal x-ray analysis. Hydrogen bonds between O(20) and N(6) as well as O(21) and N(1) connect the corticoid side chain to an adenine molecule. The molecules are also packed such that a second adenine moiety is situated over the delta4-3-one region of the steroid. These observations of the solid state suggest ways in which steroids and nucleic acids may interact in vivo.

Adenine↗
PubMed1972

Valinomycin crystal structure determination by direct methods.

The conformation of an uncomplexed form of the antibiotic valinomycin (C(54)N(6)O(18)H(90)) has been determined by direct methods including a novel technique for strong enantiomorph discrimination via the calculation and systematic analysis of cosine invariants of a special type. The intramolecular hydrogen bonding scheme and the isopropyl group stereochemistry of uncomplexed valinomycin are compatible with interpretations of spectral measurements for the complexed and uncomplexed molecule in solution but are different from any previously proposed structure. The simple conformational change of a hydrogen bond shift, which could be induced by the process of potassium ion complexing, transforms the uncomplexed into the complexed structure.

Anti-Bacterial Agents↗
PubMedDate not supplied

Molecular conformation and protein binding affinity of progestins.

Analysis of X-ray data concerning 277 estranes, androstanes, and pregnanes and comparison with progesterone receptor binding data have prompted the following observations. In general: 1. The flexibility of natural steroid hormones permits them to take up conformations optimal for binding to sites on proteins that vary in individual structural requirements. 2. When substituents strain the fused ring system, the strain will be delocalized and often transmitted to the most flexible point of the molecule, thus giving rise to conformational transmission effects. Consequently, substituents will generally stabilize a specific conformation, limiting protein interaction and enhancing a specific hormone response. 3. Hydrogen bond patterns in crystals can be used to predict points of active site attachment. 4. Distortions resulting from crystal packing forms are insignificant. Progestin receptor binding affinity: 5. Complementarity of fit is not specific on the alpha and beta faces of the B, C, and D rings. 6. The delta4-3-one composition is the only consistently required element. 7. Five of the eight highest-affinity binders have inverted A rings. Others may be easily converted to it. 8. The inverted A ring is proposed as the optimal conformation and primary factor controlling binding. 9. An A ring binding pattern is apparent in other steroidal hormones. 10. The D-ring region is open to contribute to conformational change in the receptor or genome interaction.

Crystallization↗