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Biomedical subjects

W Fuller

Publications and source records attributed to W Fuller.

At least 37 records · Page 2Linked to original sources
PubMed1986

Time-resolved X-ray diffraction studies of the B in equilibrium D structural transition in the DNA double helix.

Because of the relation between topology and function, there has been much interest in the structural transitions of the various conformations of DNA polymers. The x-ray fiber diffraction analysis system at the Daresbury Synchrotron Radiation Source was used to study the reversible transition between the B and D forms of the synthetic DNA poly[d(A-T)].poly[d(A-T)]. The gradual progression of conformations between these two forms indicates that the DNA double helix does not undergo a change of handedness during this transition.

DNA↗
PubMed1983

Conformational transitions in the synthetic polynucleotide poly[d(G-C)] . poly[d(G-C)] double-helix.

Conditions are described for observing by X-ray fibre diffraction the A, B and S conformations of the poly[d(G-C)] . poly[d(G-C)] double-helix and also a new form designated as B". For fibres with an appropriate ionic content, transitions between these conformations can be induced by varying the relative humidity of the fibre environment. With increasing relative humidity the transitions B" leads to A leads to S leads to B occur. However, reducing the relative humidity does not result in a simple reversal of these transitions. If the relative humidity is reduced rapidly, a B leads to A transition is observed followed by an A leads to B" transition, but if it is reduced slowly, the transition is from B to S. Once the S form has been assumed, further reduction in the relative humidity does not result in a transition to the A form. The S form emerges as a particularly stable form of the poly[d(G-C)] . poly[d(G-C)] double-helix. From the point of view of its relationship to the classical A and B forms, the S form of poly[d(G-C)] . poly[d(G-C)] is shown to exhibit similarities to the D form of poly[d(A-T)] . poly[d(A-T)].

Humidity↗
PubMed1983

Conformational transitions in oriented fibres of the synthetic polynucleotide poly[d(AT)].poly[d(AT)] double helix.

The synthetic polynucleotide poly[d(AT)].poly[d(AT)] is of interest in studies of the relationship between nucleic acid structure and function. In particular, A + T-rich regions in DNA double helices have been invoked as centres for controlling the transcription of genetic information. Here we describe conditions for observing by X-ray fibre diffraction the A, B, C and D conformations of Na-poly[d(AT)].poly[d(AT)], and for inducing transitions between these conformations. The D form emerges as a particularly stable conformation; once assumed, it persists over a wide range of variation in the relative humidity of the fibre environment. Further, while transitions between the B and D conformations are readily reversible, transitions between A and D are much more complex.

Nucleic Acid Conformation↗
PubMed1969

Stereochemical analysis of the specificity of pancreatic RNAse with polyformycin as substrate: differentiation of the transphosphorylation and hydrolysis reactions.

A stereochemical analysis of the substrate and inhibitor specificities of bovine pancreatic ribonuclease A is presented. A scheme is proposed in which the binding specificity for this protein-nucleic acid interaction is rationalized in terms of a simple system of H-bonds. The functional groups that govern substrate binding for transphosphorylation and hydrolysis, respectively, are considered and differentiated, and predictions are offered concerning the interaction of presumptive substrates with RNase.

Animals↗