Mo-HLPs: New flocculating agents identified from Moringa oleifera seeds belong to the hevein-like peptide family.

Cationic peptides found in Moringa oleifera seeds belong to different protein families and are described as the main flocculating agents of the species. In this study we report the identification and isolation of four new flocculant peptides, called Mo-HLPs 1-4, belonging to the family of hevein-like peptides, previously only known for their members' antimicrobial activity. Purification of the peptides followed two sequential membrane ultrafiltration steps and separation by reverse-phase liquid chromatography. Proteomic analyses showed that Mo-HLPs are extremely basic (pI >10) cysteine-rich molecules with molecular masses between 4.5 and 4.8 kDa and with a highly conserved chitin-binding domain. Searches in BLAST revealed high similarity of Mo-HLPs with hevein and other hevein-like peptides and 90% identity with morintides, which are members of the 8C-hevein-like subfamily found in M. oleifera leaves. Mo-HLPs microflocculation assays showed distinct coagulation/flocculation efficiencies, promoting turbidity reduction levels between 67 and 89% in synthetic turbid water. Activity variations were attributed to the substitution of some amino acids among the isoforms, which may have altered the final net charge of the molecules. The identification of Mo-HLPs represents the discovery of a new group of cationic peptides involved in the flocculation properties of M. oleifera seeds. SIGNIFICANCE: The study reveals the presence of hevein-like peptides in Moringa oleifera seeds. It is reported for the first time that members of this family have properties to act as flocculating agents of importance for water treatment processes. The identification of these peptides as well as new functional assignment broadens the horizon for speculation on new species which could act as sources of green coagulants for sustainable water treatment, and contributes to the knowledge about occurrence, distribution, molecular and active diversity of peptides belonging to the hevein-like family.

Seed protein variation among pepper (Capsicum sp.) genotypes revealed by MALDI-TOF analysis.

A method for seed proteome analysis using MALDI-TOF mass spectrometry is described. The data were used to estimate the genetic diversity degree among twelve genotypes of pepper (Capsicum). The resulting spectra were converted into a binary matrix consisting of 23 protein data sets, and genetic similarity values were calculated with the FreeTree software and Jaccard's coefficient of similarity. We have also been able to identify the presence of certain proteins in the extracts, by checking their masses on on-line databases.

The binding of zinc(II) to Mung Bean Nuclease. A voltammetric study.

Binding of zinc to Mung Bean Nuclease was investigated by anodic stripping voltammetry and cyclic voltammetry. These methods rely on the direct monitoring of the oxidation current of zinc in the absence and presence of Mung Bean Nuclease. Titration curves of Zn(2+) with the enzyme were obtained in concentrations ranging from 1.08x10(-9) to 1.07x10(-8) M and 1.16x10(-8) to 1.04x10(-7) M. The acquired data were used to calculate the dissociation constant and the stoichiometry of the complex. The binding sites of zinc in the Mung Bean Nuclease molecule were investigated using cyclic voltammetry. Two types of binding sites for zinc were identified and were attributed to a mononuclear exposed zinc-binding site with catalytic function and to an inaccessible binuclear zinc-binding site with structural functions.

Characterization of pearl millet prolamins.

We report the physical-chemical characterization of the major alcohol-soluble proteins present in seeds of pearl millet (Pennisetum glaucum) by SDS-PAGE, bidimensional gel electrophoresis, MALDI-TOF/MS and RP-HPLC. We demonstrate the presence of three major prolamins, called A-, B- and C-pennisetin with mass values around 27, 22 and 12 kDa, respectively. We present partial amino acid sequences of these major proteins, which should allow the posterior isolation of the respective genes.