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J Santoro

Publications and source records attributed to J Santoro.

At least 55 records · Page 3Linked to original sources
PubMed1992

The homologous angiogenin and ribonuclease N-terminal fragments fold into very similar helices when isolated.

The solution structure of the N-terminal hexadecapeptide of human angiogenin, a protein of unknown tertiary structure, has been precisely delineated by the combined use of CD, NOE and secondary shift data. A helix that starts just after Ser 3 and ends at Asp 14 was stabilized in 30% trifluoroethanol. This helix is strikingly similar in origin and length to the one formed by its homologous, the S-peptide of Ribonuclease (conformationally reexamined here), despite their quite different sequences (only four conserved residues). These results support the idea that individual start and stop signals indeed govern the location and size of natural isolated helices.

Amino Acid Sequence↗
PubMed1992

Viral diagnosis.

Explore the source record for details and available documents.

Cytomegalovirus↗
PubMed1991

Tendamistat (12-26) fragment. NMR characterization of isolated beta-turn folding intermediates.

In order to determine whether regions of a protein that are turns in the native structure are able to maintain such a structure when isolated, we have studied the conformational properties of various peptide fragments corresponding to the 12-26-peptide region of the alpha-amylase inhibitor tendamistat, by NMR. Amide solvent accessibility, NOE spectroscopy (NOESY) and rotating-frame NOE spectroscopy (ROESY) data strongly support the conclusion that the 12-26 and 15-23 peptides adopt in aqueous solution, a set of turn-like structures located around the central region of their corresponding polypeptidic chains, the same region where a beta turn exists in the native protein. Such a set of structures are destabilized when one residue located within the native beta turn of the 15-23 peptide is modified Trp18----Ser. Our results indicate that the tendency to bend in a predetermined region of a protein chain seems to exist from the very beginning of the folding process and therefore it could drive the folding instead of being a consequence of the tertiary assembly of the protein.

Amides↗
PubMed1991

3D structure of bovine pancreatic ribonuclease A in aqueous solution: an approach to tertiary structure determination from a small basis of 1H NMR NOE correlations.

A method is proposed to generate initial structures in cases where the distance geometry method may fail, such as when the set of 1H NMR NOE-based distance constraints is small in relation to the size of the protein. The method introduces an initial correlation between the phi and psi backbone angles (based on empirical observations) which is relaxed in later stages of the calculation. The obtained initial structures are refined by well-established methods of energy minimization and restrained molecular dynamics. The method is applied to determine the solution structure of Ribonuclease A (124 residues) from a NOE basis consisting of 467 NOE cross-correlations (97 intra-residue, 206 sequential, 23 medium-range and 141 long-range) obtained at 360 MHz. The global shape and backbone overall fold of the eight final refined structures are close to those shown by the crystal structure. A meaningful difference in the positioning of the catalytically important His119 side chain in the solution and crystal structures has been detected.

Amino Acid Sequence↗
PubMed1990

Solution structure of the isolated ribonuclease C-terminal 112-124 fragment.

The conformational properties of the ribonuclease C-terminal 112-124 fragment have been studied by CD and 1H- and 13C-NMR in an attempt to determine whether native secondary structure elements other than alpha-helices have stability enough to be detected when isolated in aqueous solution. Only sequential alpha N and intraresidue NOE cross-peaks are observed in the NOESY spectra, a fact which points towards an essentially extended polypeptidic chain. Observed spectral variations with temperature, pH and urea addition allowed the identification of two non-random regions within the chain. The first one is located within residues 119-121, the same region where a native salt bridge (H119...D121) exists in the native protein, and the stability of that structure is affected by the protonation state of carboxylate groups. The second one involves the S123 and V124 residues at the C-terminal end. No signs of the native 112-115 beta-turn were detected which suggests that, in contrast to alpha-helices, long range interactions may be needed to stabilize these secondary structure elements.

Carbon Isotopes↗
PubMed1990

Effect of tenoxicam on inflammation and immune cellular function.

1. We have shown that nonsteroidal anti-inflammatory drugs are potent inhibitors of neutrophil activation. Tenoxicam is a new compound of the oxicam family which has been shown to be effective for routine clinical use. 2. In the present study we examined the immune pharmacological effects of this compound on lymphocyte function by determining its effect on the expression of IL-2 receptors, on monocyte function by looking at chemotaxis and IL-1 release and on neutrophil function by evaluating the chemotactic response to a standard stimulus. 3. The data show that Tenoxicam inhibits the neutrophil and monocyte functional chemotactic response in vitro, and to some extent in vivo for monocytes, but has no effect on the expression of IL-2 receptors or IL-1 release. Tenoxicam inhibits the mobilization of neutrophils and monocytes to inflammatory sites, even though this effect was not clearly demonstrable when cells were tested after oral use.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

Sequential 1H-NMR assignment and solution structure of bovine pancreatic ribonuclease A.

Assignments for 1H-NMR resonances of most of the residues of bovine pancreatic ribonuclease (RNase A) have been obtained by sequence-specific methods. Identification and classification of spin systems have been carried out by two-dimensional phase-sensitive correlated spectroscopy (360 MHz) and single relayed coherence transfer spectroscopy. Sequence-specific assignments have been achieved by phase-sensitive two-dimensional nuclear Overhauser effect spectroscopy. To overcome the problem of spectral overlap use has been made of (a) an exhaustive analysis of partly exchanged RNase A (spectra in D2O), (b) a comparison with the subtilisin-modified enzyme (RNase S) and (c) small spectral perturbations caused by changes in pH and temperature. The secondary structure elements have been identified from the observed sequential, medium and long-range nuclear Overhauser effects together with data from amide-exchange rates. All information collected leads to the conclusion that the crystal and the solution structures are closely similar.

Amino Acid Sequence↗
PubMed1989

Vancomycin. A new old agent.

Interest in vancomycin has been rekindled by the emergence of resistant gram-positive pathogens and the improvement in drug purity. The antimicrobial activity, pharmacokinetics, clinical indications, dosing schedules, and adverse reactions of vancomycin are summarized.

Bacterial Infections↗
PubMed1988

Conformational properties of the isolated 1-23 fragment of human hemoglobin alpha-chain.

With the purpose of establishing whether, as a general rule, regions of a protein chain that are helical in the native structure maintain, at least partially, the same helical structure when isolated in solution, we have prepared the 1-23 fragment of human hemoglobin alpha-chain, and studied its conformational properties in aqueous solution by CD and 1H-NMR. From the analysis of CD and NMR spectral changes with temperature, salt and addition of trifluoroethanol (TFE) it can be concluded that the 1-23 peptide forms a measurable population (18% at 22 degrees C (pH 5.6) TFE/H2O, 30:70 (v/v)) of an alpha-helix structure that spans the same residues that are helical in the native protein (namely, 6 to 17). These results, taken together with similar ones obtained previously in the 1-19, 21-42 and 50-61 RNAase fragments, support the idea that no helices other than the native ones are actually formed in solution by protein fragments. This implies that the final helical structure of a protein is present from the very beginning of the folding process, and also that such elements of secondary structure can act as primary nucleation centers.

Circular Dichroism↗
PubMed1988

Nuclear Overhauser effects in aqueous solution as dynamic probes in short linear peptides.

The possibility of obtaining interresidue NOEs from short linear peptides in aqueous solution has been investigated from an experimental point of view using peptides of various lengths (namely GGRA, LHRH and RNase S-peptide). It is shown that, provided that long (approximately 800 ms) NOESY mixing times are used, complete sets of sequential alpha N NOEs are obtainable. From the intensities and signs of the observed NOEs, the relative mobilities of different parts of the polypeptide chain can be determined.

Gonadotropin-Releasing Hormone↗
PubMed1988

1H-NMR assignment and folding of the isolated ribonuclease 21-42 fragment.

We show in this paper that the isolated bovine ribonuclease 21-42 fragment is able to adopt in water solution a measurable population (14% at 22 degrees C, pH 5.4) of a native-like alpha-helical structure. Strong support for this conclusion is given by the analysis of CD data and 1H chemical shift variations with the temperature and the addition of stabilizing (trifluoroethanol) and denaturing (urea) agents. This results gives experimental support to the idea that native isolated secondary structure elements (at least alpha helices) are, as a rule, partially stable in solution and therefore they can act as independent protein-folding nucleation centers.

Animals↗
PubMed1987

1H NMR and CD evidence of the folding of the isolated ribonuclease 50-61 fragment.

In our search for potential folding intermediates we have prepared and characterized the fragment of RNase A corresponding to residues 50-61. Proton chemical shift variations with temperature, addition of stabilizing (TFE) or denaturing agents (urea) provide a strong experimental basis for concluding that in aqueous solution this RNase fragment forms an alpha-helix structure similar to that in the intact RNase A crystal. This conclusion lends strong support to the idea that elements of secondary structure (mainly alpha-helices) can be formed in the absence of tertiary interactions and act as nucleation centers in the protein folding process.

Circular Dichroism↗
PubMed1987

Clinical efficacy of ciprofloxacin therapy for gram-negative bacillary osteomyelitis.

The efficacy and toxicity of ciprofloxacin, an orally administered fluoroquinolone, were evaluated in 24 infections in 23 patients with osteomyelitis caused by aerobic gram-negative bacilli. The diagnosis was confirmed by surgical findings and the results of bone biopsy and culture of bone or deep soft tissue. The aerobic gram-negative bacilli were Pseudomonas aeruginosa (15 isolates), Serratia marcescens (five isolates), Escherichia coli (three isolates), Enterobacter species (three isolates), Proteus mirabilis (one isolate), Pseudomonas fluorescens (one isolate), and Klebsiella pneumoniae (one isolate). Minimal bactericidal concentrations (MBCs) were 1.56 micrograms/ml or less for all but one isolate. Nine infections were polymicrobial, involving aerobic gram-positive cocci or anaerobes in addition to aerobic gram-negative bacilli. Additional antibiotics to which the aerobic gram-negative bacilli were resistant were given when the additional organisms were resistant to ciprofloxacin. Patients received 750 mg of ciprofloxacin twice daily for a mean of 62 days. Peak serum levels of ciprofloxacin were at least threefold higher than the MBCs in 20 of 24 patients. Twenty of 22 infections in which a full course of therapy was completed were without evidence of active disease at one to 17 months posttreatment. A sternotomy wound infection relapsed after eight weeks of therapy with a newly resistant S. marcescens strain, and an infection of a compound fracture relapsed two months posttreatment with a still sensitive P. aeruginosa strain. Toxicity was minimal in most patients: eosinophilia (six patients), nausea (eight patients), mild elevation in transaminase levels (three patients), pruritus (one patient), diarrhea (two patients), thrush (two patients), rash (two patients), and mild leukopenia (one patient). Two additional patients had severe side effects (vertigo in one and acute renal failure in another) that required discontinuation of ciprofloxacin therapy. Overall, ciprofloxacin is a promising agent for the oral treatment of gram-negative bacillary osteomyelitis.

Administration, Oral↗
PubMed1987

1H-n.m.r. study of the folding of ribonuclease 12-(beta-(3-pyridyl)-L-Ala) S-peptide (1-14).

The 1H-n.m.r. spectra (360 MHz) of 12-(beta-(3-pyridyl)-L-Ala) ribonuclease S-peptide (1-14), a tetradecapeptide incorporating (beta-3-pyridyl-L-Ala) instead of His at position 12, have been assigned. The shift vs. temperature dependence has been analyzed at three different pD's in terms of a two-state helix (3-13) in equilibrium coil equilibrium, and the corresponding values for the thermodynamic quantities delta H degrees and delta S degrees determined. Helix populations at 0 degrees C have been measured as a function of pD, showing their dependence on two apparent pKa's at approximately 3.3 and 5.5, with a maximum at pD approximately 4.2. All the obtained results show that the new peptide has very similar folding properties to those shown by S-peptide and particularly to those of C-peptide. The 3-13 helix formed is stabilized by two interactions: a salt-bridge Glu 2-...Arg 10+ and a partial stacking between the aromatic rings of residues Phe 8 and His 12. Calculations involving ring current shifts and potential energies validate the possible existence of this latter interaction, which must present a local geometry defined by chi 81 180 degrees, chi 82 100 degrees, chi 121-60 and chi 122 80.

Kinetics↗