Nuclease structure and catalytic function: Current Opinion in Structural Biology 1992, 2:84…-92

Secondary structure prediction: Current Opinion in Structural Biology 1992, 2:237–241

Antibody engineering.

Lipid transmembrane asymmetry and flip-flop in biological membranes and in lipid bilayers: Current Opinion in Structural Biology 1993, 3:489–494

Transcription factor interactions: basics on zippers: Current Opinion in Structural Biology 1991, 1:71–79

DNA conformation and configuration in protein-DNA complexes: Current Opinion in Structural Biology 1992, 2:71…-77

Updating structure-function relationships in the bZip family of transcription factors: Current Opinion in Structural Biology 1992, 2:116…-123

Protein engineering for molecular electronics.

HIV protease-ligand complexes: Current Opinion in Structural Biology 1993, 3: 868–874

Carbohydrates and glycoconjugates Biophysical methods: Web alert

Catalysis and regulation: Proteins: Web alert

Native Mass Spectrometry for Structural Biophysics

The electrostatic behavior of titrating groups in alpha-sarcin was investigated using 1H NMR spectroscopy. A total of 209 chemical shift titration curves corresponding to different protons in the molecule were determined over the pH range of 3.0-8.5. Nonlinear least-squares fits of the data to simple relationships derived from the Henderson-Hasselbalch equation led to the unambiguous determination of pKa values for all glutamic acid and histidine residues, as well as for the C-terminal carboxylate and most of the aspartic acids in the free enzyme. The ionization constants of catalytically relevant histidines, His50 and His137, and glutamic acid, Glu96, in the alpha-sarcin-2'-GMP complex were also determined. The pKa values of 15 ionizable groups (C-carboxylate, six aspartic acids, four glutamic acids, and four histidines) were found to be close to their normal values. On the other hand, a number of side chain groups, including those in the active center, showed pKa values far from their intrinsic values. Thus, the pKa values for active site residues His50, Glu96, and His137 were 7.7, 5.2, and 5.8 in the free enzyme and 7.6, approximately 4.8, and 6.8 in the alpha-sarcin-2'-GMP complex, respectively. The pKa values and the activity profile against ApA, as a function of pH, are in agreement with the proposed enzymatic mechanism (in common with RNase T1 and the family of the microbial ribonucleases), in which Glu96 and His137 act as a general base and general acid, respectively. In almost all microbial ribonucleases, a Phe-His interaction is present, which affects the pKa of one of the His residues at the active site (His137). The absence of this interaction in alpha-sarcin would explain the lower pKa value of this His residue, and provides an explanation for the decreased RNase activity of this protein as compared to those of other microbial ribonucleases.

Sexual Risk and Perception of Risk for HIV Infection Among Multiethnic Family-Planning Clients

More review content in TIM 2003

A nationwide study of sexual behavior was undertaken among 4,680 randomly selected Danes aged 18-59 years. The median number of sexual partners (lifetime) was highest for men aged 30-34 years (eight partners) and for women aged 25-29 years (seven partners). After adjustment for age and sex, having had greater than or equal to 5 sexual partners in the past year was strongly associated with living in larger cities, intravenous drug use, and having sex with a prostitute, a bisexual man, an intravenous drug user, or a resident of sub-Saharan Africa. The frequency of ever having had anal intercourse was highest among women aged 20-34 years (range, 27%-36%) and was independently associated only with increasing number of sexual partners (lifetime). Overall, 2.7% of men reported any homosexual experience, among whom most (88%) had also had heterosexual intercourse. Prostitute contact (ever) was reported by 13% of all men and was associated with a high educational level, a history of travel, a greater number of sexual partners, and intravenous drug use. Overall, sexual contact with someone considered at high risk of human immunodeficiency virus (HIV) infection (a homosexual/bisexual man, intravenous drug user, prostitute, or sub-Saharan African resident) was reported by 15.9% of men and 4.8% of women. Among active blood donors (past year), 12.5% of men and 4.0% of women had engaged in potentially risky behavior. HIV testing was deliberately sought more often by respondents exposed to someone at increased risk of HIV infection (10.6%) than by those unexposed (6.5%, p less than 0.01). Exposure to persons at risk of HIV infection is considerable in Denmark. The majority of persons who have had potential exposure to HIV have not yet been tested for HIV.