Study protocol to investigate biomolecular muscle profile as predictors of long-term urinary incontinence in women with gestational diabetes mellitus.

BACKGROUND: Pelvic floor muscles (PFM) and rectus abdominis muscles (RAM) of pregnant diabetic rats exhibit atrophy, co-localization of fast and slow fibers and an increased collagen type I/III ratio. However, the role of similar PFM or RAM hyperglycemic-related myopathy in women with gestational diabetes mellitus (GDM) remains poorly investigated. This study aims to assess the frequency of pelvic floor muscle disorders and pregnancy-specific urinary incontinence (PS-UI) 12 months after the Cesarean (C) section in women with GDM. Specifically, differences in PFM/RAM hyperglycemic myopathy will be evaluated. METHODS: The Diamater is an ongoing cohort study of four groups of 59 pregnant women each from the Perinatal Diabetes Research Centre (PDRC), Botucatu Medical School (FMB)-UNESP (São Paulo State University), Brazil. Diagnosis of GDM and PS-UI will be made at 24-26 weeks, with a follow-up at 34-38 weeks of gestation. Inclusion in the study will occur at the time of C-section, and patients will be followed at 24-48 h, 6 weeks and 6 and 12 months postpartum. Study groups will be classified as (1) GDM plus PS-UI; (2) GDM without PS-UI; (3) Non-GDM plus PS-UI; and (4) Non-GDM without PS-UI. We will analyze relationships between GDM, PS-UI and hyperglycemic myopathy at 12 months after C-section. The mediator variables to be evaluated include digital palpation, vaginal squeeze pressure, 3D pelvic floor ultrasound, and 3D RAM ultrasound. RAM samples obtained during C-section will be analyzed for ex-vivo contractility, morphological, molecular and OMICS profiles to further characterize the hyperglycemic myopathy. Additional variables to be evaluated include maternal age, socioeconomic status, educational level, ethnicity, body mass index, weight gain during pregnancy, quality of glycemic control and insulin therapy. DISCUSSION: To our knowledge, this will be the first study to provide data on the prevalence of PS-UI and RAM and PFM physical and biomolecular muscle profiles after C-section in mothers with GDM. The longitudinal design allows for the assessment of cause-effect relationships between GDM, PS-UI, and PFMs and RAMs myopathy. The findings may reveal previously undetermined consequences of GDM.

Active site mapping of Loxosceles phospholipases D: Biochemical and biological features.

Brown spider phospholipases D from Loxosceles venoms are among the most widely studied toxins since they induce dermonecrosis, triggering inflammatory responses, increase vascular permeability, cause hemolysis, and renal failure. The catalytic (H12 and H47) and metal-ion binding (E32 and D34) residues in Loxosceles intermedia phospholipase D (LiRecDT1) were mutated to understand their roles in the observed activities. All mutants were identified using whole venom serum antibodies and a specific antibody to wild-type LiRecDT1, they were also analyzed by circular dichroism (CD) and differential scanning calorimetry (DSC). The phospholipase D activities of H12A, H47A, H12A-H47A, E32, D34 and E32A-D34A, such as vascular permeability, dermonecrosis, and hemolytic effects were inhibited. The mutant Y228A was equally detrimental to biochemical and biological effects of phospholipase D, suggesting an essential role of this residue in substrate recognition and binding. On the other hand, the mutant C53A-C201A reduced the enzyme's ability to hydrolyze phospholipids and promote dermonecrosis, hemolytic, and vascular effects. These results provide the basis understanding the importance of specific residues in the observed activities and contribute to the design of synthetic and specific inhibitors for Brown spider venom phospholipases D.

Structural insights into selectivity and cofactor binding in snake venom L-amino acid oxidases.

L-Amino acid oxidases (LAAOs) are flavoenzymes that catalytically deaminate L-amino acids to corresponding α-keto acids with the concomitant production of ammonia (NH(3)) and hydrogen peroxide (H(2)O(2)). Particularly, snake venom LAAOs have been attracted much attention due to their diverse clinical and biological effects, interfering on human coagulation factors and being cytotoxic against some pathogenic bacteria and Leishmania ssp. In this work, a new LAAO from Bothrops jararacussu venom (BjsuLAAO) was purified, functionally characterized and its structure determined by X-ray crystallography at 3.1 Å resolution. BjsuLAAO showed high catalytic specificity for aromatic and aliphatic large side-chain amino acids. Comparative structural analysis with prokaryotic LAAOs, which exhibit low specificity, indicates the importance of the active-site volume in modulating enzyme selectivity. Surprisingly, the flavin adenine dinucleotide (FAD) cofactor was found in a different orientation canonically described for both prokaryotic and eukaryotic LAAOs. In this new conformational state, the adenosyl group is flipped towards the 62-71 loop, being stabilized by several hydrogen-bond interactions, which is equally stable to the classical binding mode.

Intermolecular interactions and characterization of the novel factor Xa exosite involved in macromolecular recognition and inhibition: crystal structure of human Gla-domainless factor Xa complexed with the anticoagulant protein NAPc2 from the hematophagous nematode Ancylostoma caninum.

NAPc2, an anticoagulant protein from the hematophagous nematode Ancylostoma caninum evaluated in phase-II/IIa clinical trials, inhibits the extrinsic blood coagulation pathway by a two step mechanism, initially interacting with the hitherto uncharacterized factor Xa exosite involved in macromolecular recognition and subsequently inhibiting factor VIIa (K(i)=8.4 pM) of the factor VIIa/tissue factor complex. NAPc2 is highly flexible, becoming partially ordered and undergoing significant structural changes in the C terminus upon binding to the factor Xa exosite. In the crystal structure of the ternary factor Xa/NAPc2/selectide complex, the binding interface consists of an intermolecular antiparallel beta-sheet formed by the segment of the polypeptide chain consisting of residues 74-80 of NAPc2 with the residues 86-93 of factor Xa that is additional maintained by contacts between the short helical segment (residues 67-73) and a turn (residues 26-29) of NAPc2 with the short C-terminal helix of factor Xa (residues 233-243). This exosite is physiologically highly relevant for the recognition and inhibition of factor X/Xa by macromolecular substrates and provides a structural motif for the development of a new class of inhibitors for the treatment of deep vein thrombosis and angioplasty.

Purification, biochemical and functional characterization of miliin, a new thiol-dependent serine protease isolated from the latex of Euphorbia milii.

Miliin, a new thiol-dependent serine protease purified from the latex of Euphorbia milii possesses a molecular weight of 79 kDa, an isoelectric point of 4.3 and is optimally active at 60 degrees C in the pH range of and 7.5-11.0. Activity tests indicate that milliin is a thiol-dependent serine protease.

Crystallization and preliminary X-ray crystallographic analysis of the heterodimeric crotoxin complex and the isolated subunits crotapotin and phospholipase A2.

Crotoxin, a potent neurotoxin from the venom of the South American rattlesnake Crotalus durissus terrificus, exists as a heterodimer formed between a phospholipase A(2) and a catalytically inactive acidic phospholipase A(2) analogue (crotapotin). Large single crystals of the crotoxin complex and of the isolated subunits have been obtained. The crotoxin complex crystal belongs to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 38.2, b = 68.7, c = 84.2 A, and diffracted to 1.75 A resolution. The crystal of the phospholipase A(2) domain belongs to the hexagonal space group P6(1)22 (or its enantiomorph P6(5)22), with unit-cell parameters a = b = 38.7, c = 286.7 A, and diffracted to 2.6 A resolution. The crotapotin crystal diffracted to 2.3 A resolution; however, the highly diffuse diffraction pattern did not permit unambiguous assignment of the unit-cell parameters.

Insights into metal ion binding in phospholipases A2: ultra high-resolution crystal structures of an acidic phospholipase A2 in the Ca2+ free and bound states.

The electrophile Ca(2+) is an essential multifunctional co-factor in the phospholipase A(2) mediated hydrolysis of phospholipids. Crystal structures of an acidic phospholipase A(2) from the venom of Bothrops jararacussu have been determined both in the Ca(2+) free and bound states at 0.97 and 1.60 A resolutions, respectively. In the Ca(2+) bound state, the Ca(2+) ion is penta-coordinated by a distorted pyramidal cage of oxygen and nitrogen atoms that is significantly different to that observed in structures of other Group I/II phospholipases A(2). In the absence of Ca(2+), a water molecule occupies the position of the Ca(2+) ion and the side chain of Asp49 and the calcium-binding loop adopts a different conformation.

Functional expression, monodispersity and conformational changes in the SBMV virus viral VPg on binding TFE.

Southern bean mosaic virus (SBMV) RNA purified from infected plants was used for cloning the viral genome-linked protein (VPg) and was subsequently expressed in Escherichia coli. Circular dichroism (CD), dynamic light scattering (DLS) and saturation transfer difference (STD) by nuclear magnetic resonance (NMR) measurements were employed to determine the degree of monodispersity and to investigate the conformational changes in the absence and presence of trifluoroethanol (TFE) which indicated increased helical content with increasing concentration of TFE. 8-Anilino-1-naphthalenesulfonic acid (ANS) was used as a probe to compare the unfolding regions of the protein before and after addition of TFE. The results indicated that although the TFE concentration influences VPg folding, it does not play a role in nucleotide binding and that the local solvent hydrophobicity causes significant conformational changes.

Amino acid sequence of a myotoxic Lys49-phospholipase A2 homologue from the venom of Cerrophidion (Bothrops) godmani.

The complete amino acid sequence of myotoxin II (godMT-II), a myotoxic phospholipase A2 (PLA2) homologue from the venom of the Central American crotaline snake Cerrophidion (Bothrops) godmani, was determined by direct protein sequencing methods. GodMT-II is a class II PLA2 showing a Lys instead of Asp at position 49. An additional substitution in the calcium binding loop region (Asn instead of Tyr at position 28) suggests the lack of enzymatic activity observed in this toxin is due to loss of its ability to bind the co-factor Ca2+, since the residues involved in forming the catalytic network of PLA2s (His-48, Tyr-52 and Asp-99) are conserved in godMT-II. This myotoxin shows highest sequence homology with other Lys-49 PLA2 s from Bothrops, Agkistrodon and Trimeresurus species, suggesting that they constitute a conserved family of proteins, yet in contrast presents lower homology with Bothrops asper myotoxin III, a catalytically-active PLA2. The C-terminal region of godMT-II, which is rich in cationic and hydrophobic residues, shares high sequence homology to the corresponding region in the myotoxin II from B. asper, which has been proposed to play an important role in the Ca(2+)-independent membrane damaging activity.

The X-ray crystallographic structure of the angiogenesis inhibitor angiostatin.

Angiogenesis inhibitors have gained much public attention recently as anti-cancer agents and several are currently in clinical trials, including angiostatin (Phase I, Thomas Jefferson University Hospital, Philadelphia, PA). We report here the bowl-shaped structure of angiostatin kringles 1-3, the first multi-kringle structure to be determined. All three kringle lysine-binding sites contain a bound bicine molecule of crystallization while the former of kringle 2 and kringle 3 are cofacial. Moreover, the separation of the kringle 2 and kringle 3 lysiner binding sites is sufficient to accommodate the alpha-helix of the 30 residue peptide VEK-30 found in the kringle 2/VEK-30 complex. Together the three kringles produce a central cavity suggestive of a unique domain where they may function in concert.

Crystallization and preliminary X-ray crystallographic studies of the mesophilic xylanase A from Bacillus subtilis 1A1.

Xylanases have been the focus of research owing to their industrial potential in animal feed production, food processing and pulp and paper processes. In order to obtain insight into the structural stability of family 11 xylanases, the mesophilic family 11 xylanase (beta-1,4-xylan xylanohydrolase; EC 3.2.1.8) from Bacillus subtilis 1A1 has been crystallized and diffraction data have been collected to 1.7 A. The crystals belong to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 50.93, b = 70.50, c = 40.05 A. The structure has been determined by molecular replacement, resulting in a crystallographic residual of 36.4% after rigid-body refinement.

Structural Insights into Substrate Binding of Brown Spider Venom Class II Phospholipases D.

Phospholipases D (PLDs), the major dermonecrotic factors from brown spider venoms, trigger a range of biological reactions both in vitro and in vivo. Despite their clinical relevance in loxoscelism, structural data is restricted to the apo-form of these enzymes, which has been instrumental in understanding the functional differences between the class I and II spider PLDs. The crystal structures of the native class II PLD from Loxosceles intermedia complexed with myo-inositol 1-phosphate and the inactive mutant H12A complexed with fatty acids indicate the existence of a strong ligand-dependent conformation change of the highly conserved aromatic residues, Tyr 223 and Trp225 indicating their roles in substrate binding. These results provided insights into the structural determinants for substrate recognition and binding by class II PLDs.

Sequence of a cDNA encoding bothropstoxin I, a myotoxin from the venom of Bothrops jararacussu.

With the aim of further understanding the structure/function relationships in the membrane-damaging activity of the Lys49 phospholipase A2 (Lys49-PLA2) sub-family, we used PCR (polymerase chain reaction) on total venom gland cDNAs from Bothrops jararacussu with degenerate oligodeoxyribonucleotides encoding the N- and C-termini of myotoxin II, a Lys49-PLA2 from Bothrops asper. A 350-bp cDNA coding for bothropstoxin I (BtxtxI) was amplified. Sequencing of the amplified fragment shows that BtxtxI has a Lys49, and comparison with the known structure of myotoxin II showed that the amino acids involved in the formation of a novel dimeric structure in this protein were also conserved.

Isolation, characterization and biological activity of acidic phospholipase A2 isoforms from Bothrops jararacussu snake venom.

Acidic phospholipase A(2) (PLA(2)) isoforms in snake venoms, particularly those from Bothrops jararacussu, have not been characterized. This article reports the isolation and partial biochemical, functional and structural characterization of four acidic PLA(2)s (designated SIIISPIIA, SIIISPIIB, SIIISPIIIA and SIIISPIIIB) from this venom. The single chain purified proteins contained 122 amino acid residues and seven disulfide bonds with approximate molecular masses of 15 kDa and isoelectric points of 5.3. The respective N-terminal sequences were: SIIISPIIA-SLWQFGKMIDYVMGEEGAKS; SIIISPIIB-SLWQFGKMIFYTGKNEPVLS; SIIISPIIIA-SLWQFGKMILYVMGGEGVKQ and SIIISPIIIB-SLWQFGKMIFYEMTGEGVL. Crystals of the acidic protein SIIISPIIB diffracted beyond 1.8 A resolution. These crystals are monoclinic with unit cell dimensions of a = 40.1 A, b = 54.2 A and c = 90.7 A. The crystal structure has been refined to a crystallographic residual of 16.1% (R(free) = 22.9%). Specific catalytic activity (U/mg) of the isolated acidic PLA(2)s were SIIISPIIA = 290.3 U/mg; SIIISPIIB = 279.0 U/mg; SIIISPIIIA = 270.7 U/mg and SIIISPIIIB = 96.5 U/mg. Although their myotoxic activity was low, SIIISPIIA, SIIISPIIB and SIIISPIIIA showed significant anticoagulant activity. However, there was no indirect hemolytic activity. SIIISPIIIB revealed no anticoagulant, but presented indirect hemolytic activity. With the exception of SIIISPIIB, which inhibited platelet aggregation, all the others were capable of inducing time-independent edema. Chemical modification with 4-bromophenacyl bromide did not inhibit the induction of edema, but did suppress other activities.

Crystallization and preliminary diffraction data of two myotoxins isolated from the venoms of Bothrops asper (Terciopelo) and Bothrops nummifer (jumping viper).

Two myotoxins isolated from B. asper (myotoxin II) and B. nummifer (myotoxin I) snake venoms have been crystallized and their diffraction properties are described. These myotoxins are phospholipase A2 variants which lack enzymatic activity; B. asper myotoxin II is a lysine-49 phospholipase. Crystals were obtained at room temperature by standard hanging-drop vapour diffusion methods. Crystals diffracted to a resolution of 2.8 and 2.3 A, respectively.

A structure based model for liposome disruption and the role of catalytic activity in myotoxic phospholipase A2s.

Venom phospholipase A2s (PLA2s) display a wide spectrum of pharmacological activities and, based on the wealth of biochemical and structural data currently available for PLA2s, mechanistic models can now be inferred to account for some of these activities. A structural model is presented for the role played by the distribution of surface electrostatic potential in the ability of myotoxic D49/K49 PLA2s to disrupt multilamellar vesicles containing negatively charged natural and non-hydrolyzable phospholipids. Structural evidence is provided for the ability of K49 PLA2s to bind phospholipid analogues and for the existence of catalytic activity in K49 PLA2s. The importance of the existence of catalytic activity of D49 and K49 PLA2s in myotoxicity is presented.

Phospholipase A2--a structural review.

Phospholipases A2 (PLA2) are widely distributed in nature and are well characterized proteins with respect to their catalytic and pharmacological activities. A wealth of structural information has recently become available both from X-ray diffraction and NMR studies, and although a detailed model of the catalytic mechanism of PLA2 has been proposed, the structural bases of other aspects of PLA2 function, such as interfacial activation and venom PLA2 pharmacological activities, are still under debate. An appreciation of the PLA2 protein structure will yield new insights with regard to these activities. The salient structural features of the class I, II and III PLA2 are discussed with respect to their functional roles.

At the interface: crystal structures of phospholipases A2.

The protein content of many snake venoms often includes one or more phospholipases A2 (PLA2). In recent years a growing number of venoms from snakes of Agkistrodon, Bothrops and Trimeresurus species have been shown to contain a catalytically inactive PLA2-homologue in which the highly conserved aspartic acid at position 49 (Asp49) is substituted by lysine (Lys49). Although demonstrating little or no catalytic activity, these Lys49-PLA2s disrupt membranes by a Ca2+-independent mechanism of action. In addition, this family of PLA2s demonstrates myotoxic and cytolytic pharmacological activities, however the structural bases underlying these functional properties are poorly understood. Through the application of X-ray crystallography in combination with biophysical and bioinformatics techniques, we are studying structure/function relationships of Lys49-PLA2s. We here present results of a systematic X-ray crystallographic and amino acid sequence analysis study of Lys49 PLA2s and propose a model to explain the Ca2+-independent membrane damaging activity.

Crystallization and preliminary diffraction data of bothropstoxin I isolated from the venom of Bothrops jararacussu.

The myotoxic Lys-49 phospholipase bothropstoxin I was crystallized, and X-ray diffraction data were collected to 3.5 A resolution. Preliminary analysis reveals the presence of four molecules in the asymmetric unit.

Structure of a Lys49-phospholipase A2 homologue isolated from the venom of Bothrops nummifer (jumping viper).

Lys49-Phospholipase A2 (Lys49-PLA2) homologues damage membranes by a Ca2+-independent mechanism which does not involve catalytic activity. We have solved the structure of myotoxin-I, a Lys49-PLA2 homologue isolated from the venom of Bothrops nummifer (jumping viper) at 2.4 A resolution using molecular replacement techniques. The final model has been refined to a final R-factor of 18.4% (R-free = 23.2%), and shows excellent geometry. The myotoxin-I from Bothrops nummifer is dimeric in the crystalline state as has been observed for other Lys49-PLA2 homologues. In addition, a continuous electron density in the active site and substrate binding channel could be successfully modeled as a fatty-acid molecule.