Encrypted Antimicrobial Peptides from Plant Proteins.

Examples of bioactive peptides derived from internal sequences of proteins are known for decades. The great majority of these findings appear to be fortuitous rather than the result of a deliberate and methodological-based enterprise. In the present work, we describe the identification and the biological activities of novel antimicrobial peptides unveiled as internal fragments of various plant proteins founded on our hypothesis-driven search strategy. All putative encrypted antimicrobial peptides were selected based upon their physicochemical properties that were iteratively selected by an in-house computer program named Kamal. The selected peptides were chemically synthesized and evaluated for their interaction with model membranes. Sixteen of these peptides showed antimicrobial activity against human and/or plant pathogens, some with a wide spectrum of activity presenting similar or superior inhibition efficacy when compared to classical antimicrobial peptides (AMPs). These original and previously unforeseen molecules constitute a broader and undisputable set of evidences produced by our group that illustrate how the intragenic concept is a workable reality and should be carefully explored not only for microbicidal agents but also for many other biological functions.

Bradykinin-related peptides from Phyllomedusa hypochondrialis.

Bradykinin related peptides (BRPs) present in the water-soluble secretion and freshly dissected skin fragments of Phyllomedusa hypochondrialis were investigated by mass spectrometry techniques. Eighteen BRPs, along with their post-translational modifications, were characterized in the secretion by de novo MS/MS sequencing and direct MALDI imaging experiments of the frog skin. These molecules revealed strong sequence similarities to the main plasma kinin of some mammals and reptiles. Such a diversity of molecules, within the same peptide family, belonging to a single amphibian species may be related to functional specializations of these peptides and a variety of corresponding receptors that might be present in a number of different predators. Also, a novel analog, [Val]1,[Thr]6-bradykinyl-Gln,Ser had its biological activity positively detected in cell culture expressing the human bradykinin B2 receptor and in guinea pig ileum preparations.

Isolation and partial characterisation of a protein from buck seminal plasma (Capra hircus), homologous to spermadhesins.

Spermadhesins are a family of secretory proteins expressed in the male genital tract of pig, horse and bull. Their function and structure have been widely studied, especially those isolated from boar. However, there are no data concerning spermadhesins isolated from buck. Buck seminal plasma was collected and subjected to ion exchange chromatography on DEAE-Sephacel column followed by chromatography in a C18 column coupled to a HPLC system. The purification of the protein was determined by SDS-PAGE and MALDI-TOF analysis exhibiting a molecular mass of 12.5 KDa and showed to be structurally homologous to spermadhesins from boar and stallion.

Purification and characterization of a new lectin from the red marine alga Hypnea musciformis.

A lectin from the red marine alga Hypnea musciformis (HML) was purified by extraction with 20 mM PBS, precipitation with 70% saturated ammonium sulphate, ion-exchange DEAE-Cellulose chromatography and RP-HPLC. The 9.3 kDa polypeptide agglutinates erythrocytes from various sources and shows oligomerization tendencies under certain MALDI-TOF/MS conditions. Preliminary N-terminal sequencing and biological assays strongly suggest that the HML may belong to a new class of algae lectins.

[Bone marrow transplantation in chronic myeloid leukemia]. / Transplante de médula ósea en leucemia mieloide crónica.

Chronic Myelogenous Leukemia (CML) is an oncohematological disease characterized by a clonal proliferation concerning the primitive hematopoietic cell. A typical cytogenetic alteration known as Philadelphia Chromosome (Ph1), a 9:22 chromosomic translocation which produces a hybrid gene BCR/ABL, is present in 95% of the patients. Nineteen CML patients (9 female and 10 male) underwent Bone Marrow Transplantation (BMT). Median age was 32 years (range 9 to 47); 15 of them were in chronic phase (CP), and 4 in accelerated phase (AP). At diagnosis, all patients were Ph1+, BCR/ABL+. The conditioning regimen consisted of busulphan and cyclophosphamide while patients in AP received etoposide as well. Seventeen patients received cyclosporine A, methotrexate and methylprednisone as prophylaxis for Graft Versus Host Disease (GVHD) while 2 patients received only the first two drugs. The 9.22 translocation was determined by means of RT-PCT technique using the primers NB1+, Abl3, B2A, CA3 and A2. The sensitivity of the method was 1 x 10(-6). Among the 19 patients who entered the protocol, 14 are alive and in clinical, hematological and cytogenetic remission (Ph1-) and 3 patients died due to acute GVHD, 1 due to graft failure and 1 due to Hemolytic Uremic Syndrome. Of the 4 transplanted patients in AP, 3 are alive and in complete remission. The patients had a 74% survival, with a median follow-up of 655 days. Complete hematopoietic chimerism was demonstrated in 16 patients, with the study of 3 loci, D1S80, APO B and D17S30. No relationship was found between post BMT hybrid BCR/ABL (RT.PCR) persistence and disease relapse; the presence of acute and/or chronic GVHD did not influence the BCR/ABL positivity. In our experience, BMT has proved to be the only therapeutic alternative for CML with complete clinical, hematological and cytogenetic remission and a mean survival of 74%, comparable to the international experience.

Frontoxins, three-finger toxins from Micrurus frontalis venom, decrease miniature endplate potential amplitude at frog neuromuscular junction.

Neurotoxicity is a major symptom of envenomation caused by Brazilian coral snake Micrurus frontalis. Due to the small amount of material that can be collected, no neurotoxin has been fully sequenced from this venom. In this work we report six new three-finger like toxins isolated from the venom of the coral snake M. frontalis which we named Frontoxin (FTx) I-VI. Toxins were purified using multiple steps of RP-HPLC. Molecular masses were determined by MALDI-TOF and ESI ion-trap mass spectrometry. The complete amino acid sequence of FTx II, III, IV and V were determined by sequencing of overlapping proteolytic fragments by Edman degradation and by de novo sequencing. The amino acid sequences of FTx I, II, III and VI predict 4 conserved disulphide bonds and structural similarity to previously reported short-chain alpha-neurotoxins. FTx IV and V each contained 10 conserved cysteines and share high similarity with long-chain alpha-neurotoxins. At the frog neuromuscular junction FTx II, III and IV reduced miniature endplate potential amplitudes in a time-and concentration-dependent manner suggesting Frontoxins block nicotinic acetylcholine receptors.