To obtain further insight into the pathogenesis of amyloidosis and develop therapeutic strategies to inhibit fibril formation we investigated: 1) the relationship between intrinsic physical properties (thermodynamic stability and hydrogen-deuterium (H-D) exchange rates) and the propensity of human immunoglobulin light chains to form amyloid fibrils in vitro; and 2) the effects of extrinsically modulating these properties on fibril formation. An amyloid-associated protein readily formed amyloid fibrils in vitro and had a lower free energy of unfolding than a homologous nonpathological protein, which did not form fibrils in vitro. H-D exchange was much faster for the pathological protein, suggesting it had a greater fraction of partially folded molecules. The thermodynamic stabilizer sucrose completely inhibited fibril formation by the pathological protein and shifted the values for its physical parameters to those measured for the nonpathological protein in buffer alone. Conversely, urea sufficiently destabilized the nonpathological protein such that its measured physical properties were equivalent to those of the pathological protein in buffer, and it formed fibrils. Thus, fibril formation by light chains is predominantly controlled by thermodynamic stability; and a rational strategy to inhibit amyloidosis is to design high affinity ligands that specifically increase the stability of the native protein.

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In today's volatile economy, innovation in providing interactive services to consumers through a variety of channels is critical in retailing. Interactive service innovations offer opportunities for retailers by creating new markets or offering new benefits in existing markets. They also pose threats as existing customers encounter new alternatives offered by competitors. This article explores some of the most promising opportunities in interactive retail services; namely, the increasing power of consumers, channel synergies, pre- and post-transaction service, optimal use of resources, and consumer heterogeneity. In discussing these areas of opportunity we identify knowledge gaps and suggest research questions relevant to these gaps that warrant attention. Collectively, these questions offer a research agenda for the topic of interactive retail service innovation.

Cystathionine beta-synthase (CBS), a pyridoxal 5'-phosphate (PLP) dependent enzyme, catalyzes the condensation of serine and homocysteine to form cystathionine. Mammalian CBS was recently shown to be a heme protein. While the role of heme in CBS is unknown, catalysis by CBS can be explained solely by participation of PLP in the reaction mechanism. In this study, treatment of CBS with sodium borohydride selectively reduced the Schiff base but did not affect the heme. Purification and sequencing of the PLP-cross-linked peptide from a trypsin digest of the reduced enzyme revealed the evolutionarily conserved Lys119 to be the residue forming the Schiff base. Serine and hydroxylamine form an alpha-aminoacrylate and an oxime with PLP in CBS, respectively. The sulfhydryl-containing substrate, homocysteine, disturbs the heme environment but does not interact with PLP. In contrast to other PLP-dependent enzymes, CBS emits no PLP-related fluorescence when excited at 296 or 330 nm. PLP but not heme dissociates from the enzyme in the presence of hydroxylamine. The dissociation of PLP is a multistage process involving a short approximately 500 s lag phase, followed by a rapid inactivation and a slower PLP-oxime formation. PLP-free CBS exhibits a decrease of secondary structure as well as loss of CBS activity that can be only partially restored by PLP. This study constitutes the first comprehensive investigation of PLP interaction with a heme protein.

The high aqueous solubility of ionic compounds can be attributed to the ease of solvation of the counter ions. Replacement of the counter ions with ionic detergents dramatically alters the solubility properties of the molecule. Not only does the aqueous solubility drop precipitously, but the solubility in organic phases increases as well. Consequently, the partition coefficient changes by orders of magnitude. This ion pairing phenomenon, which we term hydrophobic ion pairing (HIP), has been extended to polyelectrolytes, such as proteins and polynucleotides. These materials form HIP complexes that dissolve in a range of organic solvents, often with retention of native structure and enzymatic activity. The HIP process has been used to purify protein mixtures, conduct enzymatic reactions in nonaqueous environments, increase structural stability, enhance bioavailability, and prepare new dosage forms.