Expression and bioactivity analysis of recombinant beta-CPP dimer

Transcriptomic and Metabolomic Changes Reveal the Immunomodulatory Function of Casein Phosphopeptide-Selenium Chelate in Beagle Dogs

Casein phosphopeptide-selenium chelate (CPP-Se) is an organic compound produced by the chelation of casein phosphopeptide with selenium. This compound showed the ability to modulate canine immune response in our previous study; but its effect on the peripheral blood transcriptome and serum metabolome was unknown. This study aims to reveal the potential mechanism behind the immunomodulatory function of CPP-Se. We have identified 341 differentially expressed genes (DEGs) in CPP-Se groups as compared to the control group which comprised 110 up-regulated and 231 down-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis found that DEGs were mainly involved in immune-related signaling pathways. Moreover, the immune-related DEGs and hub genes were identified. Similarly, metabolomics identified 53 differentially expressed metabolites (DEMs) in the CPP-Se group, of which 17 were up-regulated and 36 were down-regulated. The pathways mainly enriched by DEMs were primary bile acid biosynthesis, tryptophan metabolism, and other amino acids metabolic pathways. Combined analysis of transcriptomic and metabolomic data showed that the DEGs and DEMs were commonly enriched in fatty acid biosynthesis, pyrimidine metabolism, glutathione metabolism, and glycerolipid metabolic pathways. Taken together, our findings provided a theoretical basis for further understanding of the immunomodulatory function of CPP-Se as well as a scientific reference for the future use of CPP-Se in pet foods as a dietary supplement to modulate the immunity.

From amino acid sequence to bioactivity: The biomedical potential of antitumor peptides

Chemoprevention is the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. In this field, the use of antitumor peptides is of interest as, (i) these molecules are small in size, (ii) they show good cell diffusion and permeability, (iii) they affect one or more specific molecular pathways involved in carcinogenesis, and (iv) they are not usually genotoxic. We have checked the Web of Science Database (23/11/2015) in order to collect papers reporting on bioactive peptide (1691 registers), which was further filtered searching terms such as "antiproliferative," "antitumoral," or "apoptosis" among others. Works reporting the amino acid sequence of an antiproliferative peptide were kept (60 registers), and this was complemented with the peptides included in CancerPPD, an extensive resource for antiproliferative peptides and proteins. Peptides were grouped according to one of the following mechanism of action: inhibition of cell migration, inhibition of tumor angiogenesis, antioxidative mechanisms, inhibition of gene transcription/cell proliferation, induction of apoptosis, disorganization of tubulin structure, cytotoxicity, or unknown mechanisms. The main mechanisms of action of those antiproliferative peptides with known amino acid sequences are presented and finally, their potential clinical usefulness and future challenges on their application is discussed.

An E. coli over-expression system for multiply-phosphorylated proteins and its use in a study of calcium phosphate sequestration by novel recombinant phosphopeptides

Phosphoproteins and phosphopeptides were expressed by E. coli to give yields of 30-200mg of purified protein per litre with an average degree of phosphorylation at multiple sites of 61-83%. The method employed two compatible cohabiting plasmids having low and high copy number, expressing a protein kinase and, more abundantly, the substrate (poly)peptide, respectively. It was used to phosphorylate recombinant beta-casein or osteopontin at multiple casein kinase-2 sites. Two constructs were designed to produce shorter peptides containing one or more clusters of phosphorylation sites resembling the phosphate centres of caseins. In the first, a 53-residue 6-His tagged phosphopeptide was expressed at a 5-fold higher molar yield. The second had multiple tandem repeats of a tryptic phosphopeptide sequence to give a similar increase in efficiency. Each recombinant phosphopeptide was purified (30-100mg) and small-angle X-ray scattering measurements showed that they, like certain casein and osteopontin phosphopeptides, sequester amorphous calcium phosphate to form calcium phosphate nanoclusters. In principle, the method can provide novel phosphopeptides for the control of biocalcification or be adapted for use with other kinases and cognate proteins or peptides to study the effect of specific phosphorylations on protein structure. Moreover, the insertion of a phosphate centre sequence, possibly with a linker peptide, may allow thermodynamically stable, biocompatible nanoparticles to be made from virtually any sequence.