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Research has been conducted on the antimicrobial peptides which belong to the pediocin-like bacteriocin family. The role of the tryptophan residue mutations in the pediocin-like bacteriocin sakasin P has been investigated and the results are presented.

Research has been conducted on Escherichia coli tryptophan indole-lyase. The preparation of the mutant forms of the indole-lyase carried out in determining the role of these residues in the catalytic mechanism and in reaction specificity for L-tryptophan is reported.

Research has been conducted on the tryptophan-shifted mutant of phosphofructokinase from Bacillus stearothermophilus. The construction of this mutant with the fluorescence emission properties responsive to the binding of the allosteric ligands is described.

Research has been conducted on the amino acid binding domains of the tryptophanyl (TrpRS) and tryptophanyl-tRNA synthetases (TyrRS) of Bacillus stearothermophilus. The TrpRS residues mutation based on the identity of the TyrRS homologous positions has been investigated.

Fluorescence spectroscopy has been used to study single tryptophan mutants of apolipophorin-III from Locusta migratoria, apol.p-III, in discoidal lipoproteins of dimyristoylphosphatidylcholine. Helices 1, 4 and 5 appear to interact with the lipid surface, but helices 2 and 3 do not interact with the lipid. They may do it by taking on a different binding configuration from that in helices 1, 4 and 5.

An analysis of the triplet-state properties of several tryptophan analogues inserted in three nucleases of Staphylococcus is presented. Phosphorescence and optically detected magnetic resonance measurements have been done on the analogues 7-azatryptophan (7AW), 5-hydroxytryptophan (5HW) and 4-, 5-, and 6-fluorotryptophan (4FW, 5FW, 6FW). These analogues have been incorporated at position 140 of the wild-type nuclease, positions 66 and 140 of the V66W mutant and on the delta-137-149 fragment of the mutant.

Tryptophan (Trp) analogues have been inserted into Staphylococcus to study the guanidine-HCl induced unfolding of three types of nucleases. The three nucleases are the wild-type protein (WT), the V66W mutant and the delta-137-149 fragment of the mutant (V66W'). The Trp analogues used are 5-hydroxytryptophan (5HW), 7-azatryptophan (7AW), 4-fluorotryptophan (4FW), 5FW and 6FW. Results show that 5HW affects the stability of V66W' but not the WT nuclease. The 7AW analogue affects all the nucleases when substituted at positions 66 or 140. The three other analogues have negligible effect on the stability of the nucleases.

Tryptophan (Trp) analogues have been added into three nucleases of Staphylococcus to evaluate their use as intrinsic probes and their effect on the structure of the proteins. The nucleases are the the wild-type protein, its V66W mutant and the delta-137-149 fragment of the mutant. The wild-type protein has a single Trp at position 140, the V66W mutant has another Trp at position 66 and the delta-137-149 fragment has a Trp at position 66 only. The Trp analogues used include 5HW, 7AW, 4-fluorotryptophan (4FW), 5FW and 6FW.

A study was conducted to describe residual structures in an unfolfed form of yeast phosphoglycerate kinase. Fluorescence measurements were determined with a 2 mu-M protein concentration after incubation at 6 degrees C in various concentrations of Gdm-Cl or urea. A scattering solution of Ludox was utilized to record the instrumental function at the emission wavelength. Results showed that the decay of the wild-type protein was induced by two exponential terms.

The regions of the lac repressor protein involved in conformational changes in response to ligand binding in Escherichia coli were determined. Mutant repressor proteins with single tryptophans were produced by mutating each of the two native tryptophan residues to tyrosine and altering the residue of interest to tryptophan. Findings showed that in the investigated areas of the lac repressor, the inducer-bound form is different from the conformation of the unliganded form.