Purification of porcine beta-casein, N-terminal sequence, quantification in mastitic milk

Natural peptide anti-glycation effect in the presence of Aloe vera phenolic components on human serum albumin

This study explores the anti-glycation effect of aloin, in the presence and absence of casein-derived peptides, on human serum albumin HSA.

Biological activity of camel milk casein following enzymatic digestion

The aim of this study was to investigate the effects of enzymatic hydrolysis with digestive enzymes of camel whole casein and beta-casein (β-CN) on their antioxidant and Angiotensin Converting Enzyme (ACE)-inhibitory properties. Peptides in each hydrolysate were fractionated with ultra-filtration membranes. The antioxidant activity was determined using a Trolox equivalent antioxidant capacity (TEAC) scale. After enzymatic hydrolysis, both antioxidant and ACE-inhibitory activities of camel whole casein and camel β-CN were enhanced. Camel whole casein and β-CN showed significant ACE-inhibitory activities after hydrolysis with pepsin alone and after pepsinolysis followed by trypsinolysis and chymotrypsinolysis. Camel β-CN showed high antioxidant activity after hydrolysis with chymotrypsin. The results of this study suggest that when camel milk is consumed and digested, the produced peptides start to act as natural antioxidants and ACE-inhibitors.

Protein analysis by 31p NMR spectroscopy in ionic liquid: quantitative determination of enzymatically created cross-links

Cross-linking of β-casein by Trichoderma reesei tyrosinase (TrTyr) and Streptoverticillium mobaraense transglutaminase (Tgase) was analyzed by (31)P nuclear magnetic resonance (NMR) spectroscopy in ionic liquid (IL). According to (31)P NMR, 91% of the tyrosine side chains were cross-linked by TrTyr at high dosages. When Tgase was used, no changes were observed because a different cross-linking mechanism was operational. However, this verified the success of the phosphitylation of phenolics within the protein matrix in the IL. Atomic force microscopy (AFM) in solid state showed that disk-shaped nanoparticles were formed in the reactions with average diameters of 80 and 20 nm for TrTyr and Tgase, respectively. These data further advance the current understanding of the action of tyrosinases on proteins on molecular and chemical bond levels. Quantitative (31)P NMR in IL was shown to be a simple and efficient method for the study of protein modification.

Influence of dietary components on development of the microbiota in single-stomached species

After birth, development of a normal microbial community occurs gradually, and is affected by factors such as the composition of the maternal gut microbiota, the environment, and the host genome. Diet also has a direct influence, both on composition and activity of this community. This influence begins with the milk, when specific components exert their growth-promoting effect on a beneficial microbiota, thereby suppressing potential pathogens. For example, breast-fed infants compared with formula-fed babies usually have a microbial community dominated by bifidobacteria. When solid food is introduced (weaning), dramatic changes in microbial composition occur, so pathogens can gain access to the disturbed gastrointestinal (GI) ecosystem. However, use of specific dietary components can alter the composition and activity of the microbiota positively. Of all dietary components, fermentable carbohydrates seem to be most promising in terms of promoting proliferation of beneficial bacterial species. Carbohydrate fermentation results in the production of SCFA which are known for their trophic and health-promoting effects. Fermentation of proteins, on the other hand, is often associated with growth of potential pathogens, and results in production of detrimental substances including NH3and amines. In terms of the GI microbiota, lipids are often associated with the antimicrobial activity of medium-chain fatty acids and their derivatives. The present review aims to provide deeper insights into the composition and development of the neonatal GI microbiota, how this microbiota can be influenced by certain dietary components, and how this might ultimately lead to improvements in host health.

A polymeric immunoglobulin receptor-like milk protein with inhibitory activity on human immunodeficiency virus type 1 reverse transcriptase

A protein with a molecular mass of 85 kDa and an N-terminal sequence resembling polymeric immunoglobulin receptor has been isolated from bovine milk. The isolation procedure involved removal of globulin from acid whey by precipitation with 1.8 M (NH(4))(2)SO(4) followed by addition of (NH(4))(2)SO(4) to attain a concentration of 3.6 M. Subsequent steps included chromatography on CM-Sepharose and Mono S and elution of the protein of interest with a linear NaCl concentration gradient. The polymeric immunoglobulin receptor-like milk protein inhibited HIV-1 reverse transcriptase (RT) with an IC(50) of 4.8 microM. However, it did not exhibit ribonuclease activity. Neither did it inhibit translation in a cell-free rabbit reticulocyte lysate system.