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Journal Issue - Volume 11 Issue 6 (June 2002)

Abstract Protein–substrate interactions in enzymatic, neurological, and immunological systems are typically characterized by a high degree of stereoselectivity towards complex substrates. We propose a novel stereocenter‐recognition (SR) model for stereoselectivity of proteins (or receptors in general) towards substrates that have multiple stereocenters, based on the topology of substrate stereocenters. The model provides the minimum...

Abstract Using hydrogen‐deuterium exchange (HX) and electrospray ionization mass spectrometry, we have investigated the stability and structural changes of recombinant human interferon‐γ (IFN‐γ) during aggregation induced by guanidine hydrochloride (GdnHCl) and potassium thiocyanate. First, HX labeling was initiated after the amorphous aggregates were formed to probe the tertiary structure of the aggregated state. Second, labeling...

Abstract 3H‐diazirine (3H‐DZN), a photoreactive gas similar in size to water, was used to probe the topography of the surface and inner space of proteins. On photolysis 3H‐DZN generates 3H‐methylene carbene, which reacts unselectively with its molecular cage, inserting even into C‐H bonds. Labeling of bovine α‐lactalbumin (α‐LA, MW: 14,200) with 1 mM 3H‐DZN yielded 0.0041 mol CH2/mol of protein, in agreement with the expectation for an...

Abstract We used site‐directed spin labeling and electron paramagnetic resonance spectroscopy to investigate dynamics and helical packing in the four‐helix transmembrane domain of the homodimeric bacterial chemoreceptor Trg. We focused on the first transmembrane helix, TM1, particularly on the nine‐residue sequence nearest the periplasm, because patterns of disulfide formation between introduced cysteines had identified that segment...

Abstract The structural stability of calmodulin (CaM) has been investigated previously by chemical and thermal methods. The calcium‐loaded form of CaM has been found to be exceptionally stable, because it can be exposed to temperatures >90°C or to a 9 M urea solution without a marked change in its tertiary structure, and is therefore not experimentally accessible for unfolding studies using conventional analytical methods. In...

Abstract A facile method for the formation of zero‐length covalent cross‐links between protein molecules in the lyophilized state without the use of chemical reagents has been developed. The cross‐linking process is performed by simply sealing lyophilized protein under vacuum in a glass vessel and heating at 85°C for 24 h. Under these conditions, approximately one‐third of the total protein present becomes cross‐linked, and dimer is...

Abstract By means of profile‐matching procedures, conservation of functionally important residues, and fold‐recognition techniques, we show that two distinct families of lipopolysaccharide kinases encoded in the genomes of Gram‐negative bacteria are related to each other and to two distinct classes of proteins, namely eukaryotic protein kinases and right open reading frame (RIO1). Members of one of the lipopolysaccharide kinase...