C. A. Hasselbacher

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Planar-supported phospholipid bilayers formed by the adsorption of vesicles are increasingly used in the investigation of lipid-dependent reactions. We have studied the way in which these bilayers are formed with phospholipid vesicles containing the transmembrane protein Tissue Factor (TF). TF complexed with the serine protease, factor VIIa, is the primary(More)
We have used a tryptophan-requiring Escherichia coli auxotroph to replace the three tryptophan residues of lambda cI repressor with 5-hydroxy-L-tryptophan (5-OHTrp). By using a nonleaky promoter, we have achieved > 95% replacement of tryptophan in the repressor. We show that the absorbance and fluorescence properties of 5-OHTrp-lambda cI are clearly(More)
Circular dichroic (CD) spectra of three related protein pigments from Halobacterium halobium, halorhodopsin (HR), bacteriorhodopsin (BR), and sensory rhodopsin I (SR-I), are compared. In native membranes the two light-driven ion pumps, HR and BR, exhibit bilobe circular dichroism spectra characteristic of exciton splitting in the region of retinal(More)
Circular dichroism spectroscopy has been used to investigate the binding of valinomycin to bacteriorhodopsin in purple membrane suspensions. Addition of valinomycin to purple membrane suspensions obtained from Halobacterium halobium causes the circular dichroism spectrum to shift from an aggregate spectrum to one resembling a monomer spectrum, indicating a(More)
Halorhodopsin (hR) is a light-driven chloride pump located in the cell membrane of Halobacterium halobium. Fourier transform infrared difference spectroscopy has been used to study structural alterations occurring during the hR photocycle. The frequencies of peaks attributed to the retinylidene chromophore are similar to those observed in the spectra of the(More)
Effects of membrane potential on photochemical reactions of three retinal-containing chromoproteins in Halobacterium halobium, sensory rhodopsin I (sR-I), bacteriorhodopsin, and halorhodopsin, are described. Each of the three exhibits a decreased rate of thermal decay of its principal intermediate when photoactivated in an artificially energized compared to(More)
In vivo radiolabeling of Halobacterium halobium phototaxis mutants and revertants with L-[methyl-3H] methionine implicated seven methyl-accepting protein bands with apparent molecular masses from 65 to 150 kilodaltons (kDa) in adaptation of the organism to chemo and photo stimuli, and one of these (94 kDa) was specifically implicated in phototaxis. The(More)
The local environments of the four tryptophan residues of the extracellular domain of human tissue factor (sTF) were assessed from difference absorption and fluorescence spectra. The difference spectra were derived by subtracting spectra from single Trp-to-Phe or Trp-to-Tyr replacement mutants from the corresponding spectrum of the wild-type protein. Each(More)
We have synthesized a neurohypophyseal hormone analogue containing an extrinsic fluorescence probe by linking a dansyl (DNS) group to the epsilon-amino group of the lysine at residue 8 of vasotocin. The fluorescence properties of this analogue have been characterized by steady-state and time-resolved spectroscopic methods and compared with those of(More)
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