Does teacher thinking match teaching practice? A study of basic science teachers.

Objective: To obtain an understanding of basic science medical teachers' conceptions of learning and their ideas for facilitation of learning.

Methods: Teaching staff at a biomedical centre (n = 62) were asked to describe their definitions of learning, their suggestions for how to solve an applied educational problem and their intended activities when teaching students. The research was carried out using a questionnaire consisting of open-ended and fixed-choice questions.

Glutaredoxin-3 from Escherichia coli. Amino acid sequence, 1H AND 15N NMR assignments, and structural analysis.

The primary and secondary structure of glutaredoxin-3 (Grx3), a glutathione-disulfide oxidoreductase from Escherichia coli, has been determined. The amino acid sequence of Grx3 consists of 82 residues and contains a redox-active motif, Cys-Pro-Tyr-Cys, typical of the glutaredoxin family. Sequence comparison reveals a homology (33% identity) to that of glutaredoxin-1 (Grx1) from E.

Analysis of an invariant cofactor-protein interaction in thiamin diphosphate-dependent enzymes by site-directed mutagenesis. Glutamic acid 418 in transketolase is essential for catalysis.

A homologous expression system and a purification protocol for pure, highly active recombinant yeast transketolase have been developed. The invariant transketolase residue Glu418, which forms a hydrogen bond to the N-1' nitrogen atom of the pyrimidine ring of the cofactor thiamin diphosphate has been replaced by glutamine and alanine. Crystallographic analyses of the mutants show that these amino acid substitutions do not induce structural changes beyond the site of mutation.

Refined structure of transketolase from Saccharomyces cerevisiae at 2.0 A resolution.

The crystal structure of transketolase from Saccharomyces cerevisiae has been refined to a crystallographic residual of 15.7% at 2.0 A resolution using the program package X-PLOR.

An elongated form of T4 glutaredoxin with four extra residues.

Two different forms of T4 glutaredoxin (thioredoxin) arising from the same gene on a multicopy plasmid in an Escherichia coli expression system have been isolated and characterized. Up to one-fourth of purified T4 glutaredoxin has an extension of four amino acids in the carboxy terminus, with the sequence aspartate, arginine, isoleucine, lysine. This four-residue extension may be caused by a translational +1 frameshift at the UGA terminator codon.

Crystal structure analysis of a mutant Escherichia coli thioredoxin in which lysine 36 is replaced by glutamic acid.

The structure of a mutant Escherichia coli thioredoxin with a glutamic acid substituted for a conserved lysine at position 36 adjacent to the active site has been solved using molecular replacement and refined at 2.0-A resolution to a crystallographic residual of 19.9%.

Characterization of the genes of the 2,3-butanediol operons from Klebsiella terrigena and Enterobacter aerogenes.

The genes involved in the 2,3-butanediol pathway coding for alpha-acetolactate decarboxylase, alpha-acetolactate synthase (alpha-ALS), and acetoin (diacetyl) reductase were isolated from Klebsiella terrigena and shown to be located in one operon. This operon was also shown to exist in Enterobacter aerogenes. The budA gene, coding for alpha-acetolactate decarboxylase, gives in both organisms a protein of 259 amino acids.

Reduction of mutant phage T4 glutaredoxins by Escherichia coli thioredoxin reductase.

Fifteen mutant T4 glutaredoxins (previously T4 thioredoxin) have been assayed for activity with Escherichia coli thioredoxin reductase. The mutations include substitutions in the region of the active site, in the 2 cysteines, and in the 2 residues between the cysteines forming the active-site disulfide bridge. Mutant thioredoxins where substitutions have been made in charged residues around the active site show the biggest differences in activity.

Structure of oxidized bacteriophage T4 glutaredoxin (thioredoxin). Refinement of native and mutant proteins.

The structure of wild-type bacteriophage T4 glutaredoxin (earlier called thioredoxin) in its oxidized form has been refined in a monoclinic crystal form at 2.0 A resolution to a crystallographic R-factor of 0.209.

A putative glutathione-binding site in T4 glutaredoxin investigated by site-directed mutagenesis.

A glutathione monomer has been docked into the active site cleft of T4 glutaredoxin (previously called T4 thioredoxin) using molecular graphics. The central part of the cleft is formed by the side chain of Tyr-16 on one side and the residues Thr-64, Met-65, and Pro-66 on the other. The entire glutathione molecule fits well into the cleft.