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Biomedical subjects

D C Richardson

Publications and source records attributed to D C Richardson.

At least 73 records · Page 4Linked to original sources
PubMed1979

The effect of situational contingencies on female retaliative behavior.

Most studies that have found sex differences in aggression have reported that males are more aggressive than females. Recent evidence, however, suggests that the expectation of female nonaggressiveness may be unwarranted. The present study attempted to reconcile these differences by considering the contingencies of female aggression. Thirty females competed in a task designed to measure aggression (a) alone, (b) in the presence of a silent observer, or (c) in the presence of a supportive observer. Results indicated that as provocation increased, women in the private condition responded more aggressively than did women in the public condition. Also, women who responded in the presence of an audience were more aggressive when the observer was supportive than when she was silent. It is concluded that the usual findings of female nonaggressiveness may be attributable to women's expectations of disapproval for aggressive behavior.

Adult↗
PubMed1978

The beta bulge: a common small unit of nonrepetitive protein structure.

A beta bulge is a region between two consecutive beta-type hydrogen bonds which includes two residues (positions 1 and 2) on one strand opposite a single residue (position x) on the other strand. Compared to regular beta structure, a beta bulge puts the usual alternation of side-chain direction out of register on one of the strands, introduces a slight bend in the beta sheet, and locally accentuates the usual right-handed strand twist. Almost all beta bulges are between antiparallel strands, usually between a narrow rather than a wide pair of hydrogen bonds. Ninety-one examples are listed. The two commonest types are the "classic" beta bulge, with position 1 in approximately alpha-helical conformation, and the "G1" beta bulge, with a required glycine at position 1 in approximately left-handed alpha-helical conformation, G1 bulges almost always occur in combination with a type II tight turn. The functional roles of beta bulges probably include compensating for the effects of a single-residue insertion or deletion within beta structure and providing the strong local twist required for form closed beta barrel structures.

Amino Acid Sequence↗
PubMed1977

Metal sites of copper-zinc superoxide dismutase.

Silver-copper and silver-cobalt proteins have been prepared in which Ag+ resides in the native copper site of superoxide dismutase and either Cu2+ of Co2+ reside in the zinc site. The electron paramagnetic resonance (EPR) spectrum of the copper and the visible absorption spectrum of the cobalt greatly resemble those of either Cu4 of Cu2,Cu2,Co2 proteins, respectively, in which the copper of the native copper sites has been reduced. It was found that, unlike cyanide, azide anion would not perturb the EPR spectrum of Ag2,Cu2 protein. Since azide produces the same perturbation upon the EPR spectrum of native and Cu2 proteins, it must bind to the copper and not the zinc of superoxide dismutase. A model of the metal sites of the enzyme has been fitted to a 3-A electron-density map using an interactive molecular graphics display. The model shows that histidine-61, which appears to bind both copper and zinc, does not lie in the plane of the copper and its three other histidine ligands, but occupies a position intermediate between planar and axial. This feature probably accounts for the rhombicity of the EPR spectrum and the activity of the enzyme.

Azides↗
PubMed1976

Nonelectric laparoscopic sterilization. Experience with a silastic band.

In an attempt to avoid the serious complications of electrosurgical sterilization via laparoscopy, specially designed applicators have been used to apply a silastic band to the fallopian tube, thereby occluding it. Two hundred and eighty cases have been performed, 70 of which have been followed for more than 1 year. There have been no pregnancies. The technic is relatively simple. Complications result when the tube is excessively thickened, when the tube is fixed in position by adhesion, or when the tube is grasped too close to the cornua or too rapidly. These complications have been relatively few and can be easily avoided.

Anesthesia↗
PubMed1975

Crystal structure of bovine Cu,Zn superoxide dismutase at 3 A resolution: chain tracing and metal ligands.

An electron density map at 3 angstrom resolution has been calculated for Cu2+, Zn2+ superoxide dismutase from bovine erythrocytes, and the course of the main chain has been traced. The dominant structural feature is an 8-stranded barrel of antiparallel beta-pleated sheet. There is one very short helical section and two long loops of non-repetitive structure. The Cu and Zn are bound between the loops and one side of the beta barrel and are about 6 Angstrom apart, with a common histidine ligand. The Cu has four histidine ligands in a somewhat distorted square plane, and the Zn has three histidines and an aspartate in approximately tetrahedral arrangement. The two coppers of a dimer are about 34 Angstrom apart. The two subunits have essentially the same conformation and have an extensive contact area that mainly involves hydrophobic side chain interactions. The overall folding pattern of the polypeptide chain is very similar to that of an immunoglobulin domain.

Animals↗
PubMed1969

The extracellular nuclease of Staphylococcus aureus: structures of the native enzyme and an enzyme-inhibitor complex at 4 A resolution.

Independent 4 A electron density maps calculated for the extracellular nuclease of Staphylococcus aureus (based on data from three heavy-atom derivatives) and for a nuclease-thymidine-3',5'-diphosphate-calcium ion complex (based on a single isomorphous derivative) show about 60 per cent of the chain resolved, including 3(1/2) turns of helix. The pyrimidine ring of the inhibitor fits into a pocket in the enzyme and appears to be parallel to the ring of a tyrosyl residue. Conformational changes can be observed between the nuclease and the nuclease-inhibitor complex, but the two structures seem to be identical over most of the molecule.

Crystallization↗