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PubMed1993

Synthesis of rat brain natriuretic peptide 45 using tetrafluoroboric acid deprotection and silyl chloride disulfide formation.

A newly isolated rat brain natriuretic peptide 45 (rBNP45) was synthesized using the 9-fluorenylmethyloxycarbonyl (Fmoc)-based solid-phase method. Tetrafluoroboric acid (HBF4) deprotection was successfully applied for this synthesis, while the conventional trifluoroacetic acid (TFA)-thioanisole method gave unsatisfactory results. The disulfide bond of rBNP45 was constructed by using the silyl chloride method within 10 min, which was extremely advantageous to avoid the formation of Met(O)-rBNP45. The chick rectum relaxant activity of the synthetic rBNP45 was three times as potent as that of alpha-rat atrial natriuretic peptide (alpha-rANP).

Amino Acid Sequence↗
PubMed2004

Salmonella typhimurium recognizes a chemically distinct form of the bacterial quorum-sensing signal AI-2.

Bacterial populations use cell-cell communication to coordinate community-wide regulation of processes such as biofilm formation, virulence, and bioluminescence. This phenomenon, termed quorum sensing, is mediated by small molecule signals known as autoinducers. While most autoinducers are species specific, autoinducer-2 (AI-2), first identified in the marine bacterium Vibrio harveyi, is produced and detected by many Gram-negative and Gram-positive bacteria. The crystal structure of the V. harveyi AI-2 signaling molecule bound to its receptor protein revealed an unusual furanosyl borate diester. Here, we present the crystal structure of a second AI-2 signal binding protein, LsrB from Salmonella typhimurium. We find that LsrB binds a chemically distinct form of the AI-2 signal, (2R,4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran (R-THMF), that lacks boron. Our results demonstrate that two different species of bacteria recognize two different forms of the autoinducer signal, both derived from 4,5-dihydroxy-2,3-pentanedione (DPD), and reveal new sophistication in the chemical lexicon used by bacteria in interspecies signaling.

Amino Acid Sequence↗
PubMed2005

Localized influence of 2'-hydroxyl groups and helix geometry on protein recognition in the RNA major groove.

The local geometry of a DNA helix can influence protein recognition, but the sequence-specific features that contribute to helix structure are not fully understood, and even less is known about how RNA helix geometry may affect protein recognition. To begin to understand how local or global helix structure may influence binding in an RNA model system, we generated a series of DNA analogues of HIV and BIV TAR RNAs in which ribose sugars were systematically substituted in and around the known binding sites for argininamide and a BIV Tat arginine-rich peptide, respectively, and measured their corresponding binding affinities. For each TAR interaction, binding occurs in the RNA major groove with high specificity, whereas binding to the all-DNA analogue is weak and nonspecific. Relatively few substitutions are needed to convert either DNA analogue of TAR into a high-affinity binder, with the ribose requirements being restricted largely to regions that directly contact the ligand. Substitutions at individual positions show up to 70-fold differences in binding affinity, even at adjacent base pairs, while two base pairs at the core of the BIV Tat peptide-RNA interface are largely unaffected by deoxyribose substitution. These results suggest that the helix geometries and unique conformational features required for binding are established locally and are relatively insulated from effects more than one base pair away. It seems plausible that arginine-rich peptides are able to adapt to a mosaic helical architecture in which segments as small as single base steps may be considered as modular recognition units.

Amino Acid Motifs↗
PubMed1996

Synthesis of human C-type natriuretic peptide 22 using chlorotrityl resin and tetrafluoroboric acid deprotection.

Human C-type natriuretic peptide 22 (hCNP22), the third member of the natriuretic peptide family, was efficiently synthesized by Fmoc-based peptide chain construction on a 2-chlorotrityl (Clt) resin, followed by deprotection using tetrafluoroboric acid (HBF4). The use of Clt resin was effective in suppressing racemization at the C-terminal cysteine residue caused by the base treatment for Fmoc-cleavage. The disulfide bond of hCNP22 was constructed using the silyl chloride-sulfoxide method to avoid oxidation at the Met residue. Using amino acid- and dipeptide-resin derivatives, the effects of bases, protecting groups and resin supports on the racemization at the C-terminal Cys residue were examined in detail.

Amino Acid Sequence↗
PubMed1996

Discontinuous electrophoresis revisited: a review of the process.

The use and development of discontinuous buffer systems for the separation of proteins and nucleic acids are reviewed, and the advantages over a continuous buffer system are presented. Emphasis is given to the more recent applications in DNA separations where discontinuous systems have aided in the resolution and mobility tailoring of DNA fragments. Various DNA size ranges can be separated in short time periods by simple choice of buffer components rather than gel alterations. Guidelines for choosing appropriate buffer systems are offered as well as the application of borate complexes to modify the mobility of DNA. This article reviews the historical development of discontinuous buffers in the electrophoresis of proteins and nucleic acids with emphasis on the characteristics and applicability to nucleic acid separations.

Boric Acids↗
PubMed2005

A toxicity index of skin and wound cleansers used on in vitro fibroblasts and keratinocytes.

OBJECTIVE: To determine toxicity indexes of commercially available skin, wound, and skin/wound cleansers on in vitro fibroblasts and keratinocytes. DESIGN: Seventeen cleansers and 3 liquid bath soaps were evaluated for cytotoxic effect on human infant dermal fibroblasts and epidermal keratinocytes. Both skin cell types were exposed to serial 10-fold dilutions of each cleanser until treated cell viability was comparable to untreated controls. RESULTS: The experimental design allowed calculation of relative toxicity indexes ranging from 0 to 100,000. Shur-Clens, SAF-Clens, and saline were found to be the least toxic to fibroblasts (toxicity index 0); Dial Antibacterial Soap and Ivory Liqui-Gel were the most toxic (toxicity index 100,000). Biolex, Shur-Clens, and Techni-Care were the least toxic to keratinocytes (toxicity index 0); hydrogen peroxide, modified Dakin's solution, and povidone (10%) were found to be the most toxic (toxicity index 100,000). CONCLUSIONS: Successful cutaneous tissue repair depends on the viability of the principal cell types involved (fibroblasts and keratinocytes). Toxicity indexes provide helpful guidelines for subsequent in vivo evaluations and clinical applications. The study findings also suggest that judicious use of these supposedly innocuous agents should be considered in a clinical setting.

Acetic Acid↗