A monoclonal antibody recognizing an epitope shared by receptors for growth hormone, prolactin, interleukin 2 and interleukin 6.

Monoclonal antibody (MAb) termed R7B4 was generated throughout the idiotypic-anti-idiotypic network from mice immunized with human and bovine growth hormones (GH). The Ab was selected on the basis that it did not recognize human GH (hGH) neither insolubilized nor in solution but inhibited 125I-hGH binding to receptors from rat and rabbit liver and from Nb2-cell membranes. Since it inhibited Nb2-cell mitogenesis stimulated by hGH, prolactins or placental lactogens, MAb R7B4 behaved as an antagonist of lactogenic hormones.

Messages from ultrahigh resolution crystal structures.

The ever growing availability of macromolecular crystal structures determined at atomic resolution has now reached a critical size, making it possible to obtain statistically unbiased data on both protein stereochemistry and the validity of the parameters used in their refinement. Besides the determination of the precise geometry of proteins and their active sites, high resolution structures have made it possible to check the application of normal mode calculations, to calculate charge density distributions and to analyze hydration shells around protein molecules. Even if only a few structures involve protein complexes, either with ligands or prosthetic groups, the information obtained in these cases is of great interest for obtaining the physical parameters of these interactions.

Molecular cloning and bacterial expression of a general odorant-binding protein from the cabbage armyworm Mamestra brassicae.

A cDNA clone encoding a general odorant-binding protein (GOBP2) was isolated from antennal RNA of Mamestra brassicae by reverse transcription-PCR (RT-PCR) and RACE-PCR. The cDNA encoding the GOBP2 was further used for bacterial expression. Most of the recombinant GOBP2 (>90%) was found to be insoluble.

Packing forces in nine crystal forms of cutinase.

During the characterization of mutants and covalently inhibited complexes of Fusarium solani cutinase, nine different crystal forms have been obtained so far. Protein mutants with a different surface charge distribution form new intermolecular salt bridges or long-range electrostatic interactions that are accompanied by a change in the crystal packing. The whole protein surface is involved in the packing contacts and the hydrophobicities of the protein surfaces in mutual contact turned out to be noncorrelated, which indicates that the packing interactions are nonspecific.

Exploring hydrophobic sites in proteins with xenon or krypton.

X-ray diffraction is used to study the binding of xenon and krypton to a variety of crystallised proteins: porcine pancreatic elastase; subtilisin Carlsberg from Bacillus licheniformis; cutinase from Fusarium solani; collagenase from Hypoderma lineatum; hen egg lysozyme, the lipoamide dehydrogenase domain from the outer membrane protein P64k from Neisseria meningitidis; urate-oxidase from Aspergillus flavus, mosquitocidal delta-endotoxin CytB from Bacillus thuringiensis and the ligand-binding domain of the human nuclear retinoid-X receptor RXR-alpha. Under gas pressures ranging from 8 to 20 bar, xenon is able to bind to discrete sites in hydrophobic cavities, ligand and substrate binding pockets, and into the pore of channel-like structures. These xenon complexes can be used to map hydrophobic sites in proteins, or as heavy-atom derivatives in the isomorphous replacement method of structure determination.

Atomic resolution (1.0 A) crystal structure of Fusarium solani cutinase: stereochemical analysis.

X-ray data have been recorded to 1.0 A resolution from a crystal of Fusarium solani cutinase using synchrotron radiation and an imaging-plate scanner. The anisotropic treatment of thermal motion led to a fivefold increase in accuracy and to a considerable quality improvement in the electron density maps with respect to an intermediate isotropic model.

Crystal structure of cutinase covalently inhibited by a triglyceride analogue.

Cutinase from Fusarium solani is a lipolytic enzyme that hydrolyses triglycerides efficiently. All the inhibited forms of lipolytic enzymes described so far are based on the use of small organophosphate and organophosphonate inhibitors, which bear little resemblance to a natural triglyceride substrate. In this article we describe the crystal structure of cutinase covalently inhibited by (R)-1,2-dibutyl-carbamoylglycero-3-O-p-nitrophenylbutyl-phos phonate, a triglyceride analogue mimicking the first tetrahedral intermediate along the reaction pathway.

Dynamics of Fusarium solani cutinase investigated through structural comparison among different crystal forms of its variants.

In characterizing mutants and covalently inhibited complexes of Fusarium solani cutinase, which is a 197-residue lipolytic enzyme, 34 variant structures, crystallizing in 8 different crystal forms, have been determined, mostly at high resolution. Taking advantage of this considerable body of information, a structural comparative analysis was carried out to investigate the dynamics of cutinase. Surface loops were identified as the major flexible protein regions, particularly those forming the active-site groove, whereas the elements constituting the protein scaffold were found to retain the same conformation in all the cutinase variants studied.

Acyl glycerol hydrolases: inhibitors, interface and catalysis.

The last five years have witnessed the solution of a large number of lipase structures, which has led, among other insights, to the structural interpretation of the interfacial activation phenomenon in terms of 'lid' opening. This interpretation has been extended this year to include phospholipase A2. Recent structural studies on lipases have provided data on the detailed mechanisms underlying the behaviour of lipases: how they bind to inhibitors or substrates, and what interactions occur between their hydrophobic face and hydrophobic molecules, for example.

Dark solitons in degenerate optical parametric oscillators.

It is shown theoretically that a degenerate optical parametric oscillator with a frequency limiter and continuouswave pumping can generate stable dark solitons when it operates near antiresonance. These solitons are supported by the combined effect of pump depletion and spectral filtering, and their stability is ensured by the phase-dependent nature of the parametric gain.

Contribution of cutinase serine 42 side chain to the stabilization of the oxyanion transition state.

Cutinase from the fungus Fusarium solani pisi is a lipolytic enzyme able to hydrolyze both aggregated and soluble substrates. It therefore provides a powerful tool for probing the mechanisms underlying lipid hydrolysis. Lipolytic enzymes have a catalytic machinery similar to those present in serine proteinases.

Effects of dispersion on mode locking in optical parametric oscillators.

We discuss the role that group-velocity dispersion and cavity detuning play in the onset of mode locking in synchronously pumped optical parametric oscillators. Because of the phase-sensitive character of the parametric gain, it is shown for the degenerate case that dispersion effects associated with off-resonance operation can lead to subpulse structures and spectral splitting of the parametric pulses. This behavior is interpreted on the basis of a dispersion-induced interference phenomenon between the two nearly degenerate parametric photons produced by the conversion of one pump photon in the nonlinear medium.

Experimental analysis and theoretical modeling of a diode-pumped Er:Yb:glass microchip laser.

A comprehensive study of a diode-pumped Er:Yb:glass microchip laser, operating at 1530-nm wavelength, is presented. The operating conditions wherein a linearly polarized, single longitudinal and transverse mode operation is achieved are indicated. An optimum pump spot size that minimizes the threshold pump power and maximizes the slope efficiency is experimentally found and theoretically justified by a space-dependent rate-equation model.

Ultrashort-pulse generation in degenerate optical parametric oscillators.

Solitary-pulse generation in a degenerate optical parametric oscillator subjected to continuous-wave pumping is investigated theoretically. As with solitary lasers, pulse shaping is a phase effect induced by the interplay between self-phase modulation and group-delay dispersion, but pulse stability is ensured by the parametric gain itself and does not require any fast saturable absorber action.

Third-order-harmonic mode locking of a bulk erbium:ytterbium:glass laser at a 2.5-GHz repetition rate.

A bulk erbium:ytterbium:phosphate glass laser has been actively mode locked at the third-order harmonic by a bulk lithium niobate phase modulator. Light pulses of 9.6-ps duration, 2.

Variability within the Candida rugosa lipases family.

Several fungi secrete lipase isozymes differing in biochemical properties and in some cases in substrate specificity. In the yeast Candida rugosa, a family of related genes encodes for multiple lipase proteins, highly homologous in sequence but partially different in the regions interacting with the substrate molecule. Analysis of these substitutions performed on the basis of multiple alignments and using a 3-D model of the enzyme, allows identification of a restricted number of amino acids possibly involved in substrate specificity of Candida lipases.

Continuous-wave mode locking of a bulk erbium-ytterbium glass laser.

Continuous-wave mode-locking operation of a bulk Er:Yb:phosphate glass laser, pumped by either a Ti:sapphire or an InGaAs diode laser, is reported for what is to our knowledge the first time. Pulses with a 90-ps duration, a 100-MHz repetition rate, and as much as 7-mW average power have been obtained.

Diode-pumped microchip Er-Yb:glass laser.

A single-frequency, diode-pumped, Er-Yb:glass microchip laser at a 1530-nm wavelength has been designed and operated. An output power of greater than 25 mW, a linewidth narrower than 1 kHz, and a slope efficiency of 22% have been obtained.

Cloning and analysis of Candida cylindracea lipase sequences.

Lipases (Lip) hydrolyze triglycerides into fatty acids and glycerol. Lip produced by the yeast Candida cylindracea are encoded by multiple genomic sequences. We report the molecular cloning and characterization of three genes from this family.

Single-mode cw erbium-ytterbium glass laser at 1.5 microm.

Single-mode operation of a continuous-wave Er:Yb:phosphate glass laser pumped at 980 nm by a InGaAs index-guided diode laser has been achieved for what is to our knowledge the first time. The maximum output power obtained at 1540 nm is 10 mW, and the width of the spectral line is less than 15 kHz.

Homology-derived three-dimensional structure prediction of Candida cylindracea lipase.

We propose a structural model of Candida cylindracea lipase (CCL) based on the reported X-ray structure of the highly homologous Geotrichum candidum lipase (GCL). The network of interactions around the active site, the salt and disulfide bridge pattern is conserved in the proposed structure. Functional, structural and evolutionary aspects of the peculiar usage of CTG codons by C.