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Journal Issue - Volume 1 Issue 3 (March 1992)

Abstract The determination of the NMR structure of oxidized Escherichia coli glutaredoxin in aqueous solution is described, and comparisons of this structure with that of reduced E. coli glutaredoxin and the related proteins E. coli thioredoxin and T4 glutaredoxin are presented. Based on nearly complete sequence‐specific 1H‐NMR assignments, 804 nuclear Overhauser enhancement distance constraints and 74 dihedral angle constraints were obtained as the input...

Abstract We report the X‐ray analysis at 2.0 Å resolution for crystals of the aspartic proteinase endothiapepsin (EC 3.4.23.6) complexed with a potent difluorostatone‐containing tripeptide renin inhibitor (CP‐81,282). The scissile bond surrogate, an electrophilic ketone, is hydrated in the complex. The pro‐(R) (statine‐like) hydroxyl of the tetrahedral carbonyl hydrate is hydrogen‐bonded to both active‐site aspartates 32 and 215 in...

Abstract Leuconostoc mesenteroides glucose 6‐phosphate dehydrogenase (G6PD) was isolated in high yield and purified to homogeneity from a newly constructed strain of Escherichia coli which lacks its own glucose 6‐phosphate dehydrogenase gene. Lys‐21 is one of two lysyl residues in the enzyme previously modified by the affinity labels pyridoxal 5′‐phosphate and pyridoxal 5′‐diphosphate‐5′‐adenosine, which are competitive inhibitors ...

Abstract Native tropomyosin from rabbit skeletal muscle (RSTm) consists mainly of αα and αβ coiled coils (α/β ≈︁ 3–4/1). In some extant studies, no ββ molecules have been found. In this study, RSTm from several different preparations was disulfide cross‐linked, both preparation and cross‐linking being done under nondenaturing conditions. The cross‐linked product was assayed for the presence of ββ molecules cross‐linked at both C36 and C190 (β=β). In such...

Abstract Single tryptophan‐containing mutants of low adenylylation state Escherichia coli glutamine synthetase have been studied by frequency‐domain fluorescence spectroscopy in the presence of various substrates and inhibitors. At pH 6.5, the Mn‐bound wild‐type enzyme (wild type has two tryptophans/subunit) and the mutant enzymes exhibit heterogeneous fluorescence decay kinetics; the individual tryptophans are adequately described by a triple...

Abstract The glucose and N‐acetylglucosamine‐specific transporters (IIGlc/IIIGlc and IIGlcNAc) of the bacterial phosphotransferase system mediate carbohydrate uptake across the cytoplasmic membrane concomitant with substrate phosphorylation. The two transporters have 40% amino acid sequence identity. Eight chimeric proteins between the two transporters were made by gene reconstruction. All hybrid proteins could be expressed, some inhibited cell...

Abstract In vitro experiments employing the soluble proteins from Escherichia coli reveal that about half of them, in their unfolded or partially folded states, but not in their native states, can form stable binary complexes with chaperonin 60 (groEL). These complexes can be isolated by gel filtration chromatography and are efficiently discharged upon the addition of Mg · ATP. Binary complex formation is substantially reduced if chaperonin 60...

Abstract Tryptases are trypsin‐like serine proteinases found in the granules of mast cells. Although they show 40% sequence identity with trypsin and contain only 20 or 21 additional residues, tryptases display several unusual features. Unlike trypsin, the tryptases only make limited cleavages in a few proteins and are not inhibited by natural trypsin inhibitors, they form tetramers, bind heparin, and their activity on synthetic...

Abstract The β‐turn is a frequently found structural unit in the conformation of globular proteins. Although the circular dichroism (CD) spectra of the α‐helix and β‐pleated sheet are well defined, there remains some ambiguity concerning the pure component CD spectra of the different types of β‐turns. Recently, it has been reported (Hollósi, M., Koövér, K.E., Holly, S., Radics, L., & Fasman, G.D., 1987, Biopolymers 26,...

Abstract A combined force field of molecular mechanics and solvation free energy is tested by carrying out energy minimization and molecular dynamics on several conformations of the alanyl dipeptide. Our results are qualitatively consistent with previous experimental and computational studies, in that the addition of solvation energy stabilizes the C5 conformation of the alanyl dipeptide relative to the C7.

Abstract Proteins are generally classified into four structural classes: all‐α proteins, all‐β proteins, α+β proteins, and α/β proteins. In this article, a protein is expressed as a vector of 20‐dimensional space, in which its 20 components are defined by the composition of its 20 amino acids. Based on this, a new method, the so‐called maximum component coefficient method, is proposed for predicting the structural class of a protein...

Abstract The Protein Data Bank currently contains about 600 data sets of three‐dimensional protein coordinates determined by X‐ray crystallography or NMR. There is considerable redundancy in the data base, as many protein pairs are identical or very similar in sequence. However, statistical analyses of protein sequence‐structure relations require nonredundant data. We have developed two algorithms to extract from the data base...