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Journal Issue - Volume 1 Issue 11 (November 1992)

Abstract Backbone amide proton exchange rates in the DNA‐binding domain of GAL4 have been determined using 1H–15N heteronuclear correlation NMR spectroscopy. Three forms of the protein were studied — the native Zn‐containing protein, the Cd‐substituted protein, and a Zn‐GAL4/DNA complex. Exchange rates in the Zn‐containing protein are significantly slower than in the Cd‐substituted protein. This shows that Cd‐substituted GAL4 is destabilized...

Abstract The structure of the long‐chain flavodoxin from the photosynthetic cyanobacterium Anabaena 7120 has been determined at 2 å resolution by the molecular replacement method using the atomic coordinates of the long‐chain flavodoxin from Anacystis nidulans. The structure of a third long‐chain flavodoxin from Chondrus crispus has recently been reported. Crystals of oxidized A. 7120 flavodoxin belong to the monoclinic space group P21 with a = 48.0, b =...

Abstract The 1:1 complex between horse heart cytochrome c and bovine cytochrome c oxidase, and between yeast cytochrome c and Paracoccus denitrificans cytochrome c oxidase have been studied by a combination of second derivative absorption, circular dichroism (CD), and resonance Raman spectroscopy. The second derivative absorption and CD spectra reveal changes in the electronic transitions of cytochrome a upon complex formation. These results could reflect...

Abstract The replacement of Arg‐54 by Ala in the active site of Escherichia coli aspartate transcarbamoylase causes a 17,000‐fold loss of activity but does not significantly influence the binding of substrates or substrate analogs (Stebbins, J.W., Xu, W., & Kantrowitz, E.R., 1989, Biochemistry 28, 2592–2600). In the X‐ray structure of the wild‐type enzyme, Arg‐54 interacts with both the anhydride oxygen and a phosphate oxygen of carbamoyl...

Abstract The three‐dimensional structure of a modified human lysozyme (HL), Glu 53 HL, in which Asp 53 was replaced by Glu, has been determined at 1.77 å resolution by X‐ray analysis. The backbone structure of Glu 53 HL is essentially the same as the structure of wild‐type HL. The root mean square difference for the superposition of equivalent Cα atoms is 0.141 å. Except for the Glu 53 residue, the structure of the active site region is largely...

Abstract The mechanism of protein‐mediated membrane fusion and lysis has been investigated by solution‐state studies of the effects of peptides on liposomes. A peptide (SI) corresponding to a highly amphiphilic C‐terminal segment from the envelope protein (gp41) of the human immunodeficiency virus (HIV) was synthesized and tested for its ability to cause lipid membranes to fuse together (fusion) or to break open (lysis). These...

Abstract A model structure has been constructed for a monoclonal anti‐dinitrophenyl antibody. The antibody, ANO2, has been sequenced and cloned (Anglister, J., Frey, T., & McConnell, H.M., 1984, Biochemistry 23, 1138–1142). Its amino acid sequence shows striking homology with the anti‐lysozyme Fab fragments HyHel5 (83%) and HyHel10 (73%). Based on this homology, a model for the ANO2 variable heavy and variable light chain framework was...