•Seleno-β-lactoglobulin (Se-β-Lg) was firstly synthesized.•The method of synthesis of Se-β-Lg was simple.•The compound had high activity of antitumor.β-Lg is a major whey protein in cow’s milk. This study was aimed to find a new kind of organic selenium compound synthesized with β-Lg and selenium dioxide as raw materials under the conditions of vacuum and low temperature. Fourier transformed infrared spectroscopy revealed that seleno-β-lactoglobulin (Se-β-Lg) displayed a strong band at 878 cm−1, belonging to SeO. Circular dichroism spectra results indicated that the conformation of Se-β-Lg was transformed and α-helical, and unordered structures were increased by 9% and 11.2%, respectively, while β-sheet and β-turn were reduced by 14.2% and 6%, respectively. Electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry results showed that there were two protein bands (1-Seβ-Lg and 2-Seβ-Lg) in Se-β-Lg, only one β-Lg connected with selenate in 1-Seβ-Lg, but two β-Lgs, connected to each other, and with selenate, in 2-Seβ-Lg. Morphological observation and hematoxylin and eosin staining indicated that Se-β-lg could induce K562 cell apoptosis. These results indicated that Se-β-Lg could be synthesized by selenium conjugating β-Lg and it had antitumor activity.

•Se-β-lg was a novel organic selenium compound chemically synthesized.•Se-β-lg could protect oxidative stress in D-galactose-induced aging mice.•Se-β-lg could decrease TBARS and improve SOD and GSH-Px.The protective effect of Se-β-lg against oxidative stress was investigated in D-galactose (D-gal) induced aging mice. The mice were divided into seven groups: normal group, model group, selenium dioxide (SeO2) group, β-lactoglobulin group, low dose Se-β-lg group, middle dose Se-β-lg and high dose Se-β-lg group. The aging mice were induced by D-gal with subcutaneous injection. The ability of spatial learning was measured by Morris water maze (MWM). SOD, GPH-Px and thiobarbituric acid reactive substances (TBARS) were detected by Elisa assay and its gene expression was observed by real-time PCR. The results of MWM showed that Se-β-lg could remarkably enhance the ability of spatial learning and memory in the D-gal induced aging mice. Se-β-lg could significantly decrease the contents of TBARS and improve the protein and gene expression levels of SOD and GSH-Px. Our study revealed that Se-β-lg could enhance the activity of antioxidase to defend the D-gal induced aging.

•TGase enhanced the mechanical and barrier properties of gelatin–calcium carbonate composite films.•TGase promoted the crosslinking of gelatin–calcium carbonate composite films.•Gelatin–calcium carbonate composite films can act as a good edible film in food industries.The effects of transglutaminase (TGase) on the rheological profiles and interactions of gelatin–calcium carbonate solutions were studied. In addition, mechanical properties, water vapour permeability and microstructures of gelatin–calcium carbonate films were also investigated and compared. Fluorescence data suggested that the interaction of TGase and gelation-calcium carbonate belonged to a static quenching mechanism, and merely one binding site between TGase and gelatin–calcium carbonate was identified. Moreover, differential scanning calorimetry (DSC), the mechanical properties and the water vapour permeability studies revealed that TGase favoured the strong intramolecular polymerisation of the peptides in gelatin. The microstructures of the surfaces and cross sections in gelatin–calcium carbonate films were shown by scanning electron microscope (SEM) micrographs. The results of the fourier transform infrared spectroscopy (FTIR) indicated that TGase caused conformational changes in the proteins films. Therefore, TGase successfully facilitated the formation of gelatin–calcium carbonate composite films.