Alpha‐Lactalbumin: Its Production Technologies and Bioactive Peptides

Abstract

Alpha-lactalbumin (␣-La), a globular protein found in all mammalian milk, has been used as an ingredient in infant formulas. The protein can be isolated from milk using chromatography/gel filtration, membrane separation, enzyme hydrolysis, and precipitation/aggregation technologies. ␣-La is appreciated as a source of peptides with antitumor and apoptosis, antiulcerative, immune modulating, antimicrobial, antiviral, antihypertensive, opioid, mineral binding, and antioxidative bioactivities, which may be utilized in the production of functional foods. Nanotubes formed by the protein could find applications in foods and pharmaceuticals, and understanding its amyloid fibrils is important in drawing strategies for controlling amyloidal diseases. Bioactive peptides in ␣-La are released during the fermentation or ripening of dairy products by starter and nonstarter microorganisms and during digestion by gastric enzymes. Bioactive peptides are also produced by deliberate hydrolysis of ␣-La using animal, microbial, or plant proteases. The occurrence, structure, and production technologies of ␣-La and its bioactive peptides are reviewed.

Pilot-scale purification of α-lactalbumin from enriched whey protein concentrate by anion-exchange chromatography and ultrafiltration

“…The methods applied to obtain enriched fractions or purified α-La have recently been reviewed by Kamau et al (2010) and El-Sayed and Chase (2011). Extraction of α-La with high purity is not an easy task, especially at large-or pilot-scale purification, primarily due to the presence of the other major whey protein β-lactoglobulin (β-Lg).…”

Protein-Based Nanoparticles

“…α-LA nanotubes are very stable and due to their long linear structure can be used as viscosifying agents (Kaya-Celiker and Mallikarjunan 2012). The presence of an 8 nm cavity in these tubes could be useful for the possible encapsulation of nutraceuticals, vitamins, and prebiotics (Kamau et al 2010). This method is applicable to other proteins as well and has been investigated in the immobilization of enzymes or to prepare analogues to muscle fiber (Weiss et al 2006).…”

“…It is quantitatively the second most important protein in whey, has a molecular weight of 14.2 kDa, is able to bind calcium, and is the regulatory subunit of the enzyme lactose synthase (Kamau et al 2010;Kaya-Celiker and Mallikarjunan 2012). Partial hydrolysis of α-LA with a bacterial protease from Bacillus licheniformis was shown to induce the formation of nanotubes by self-assembly of the generated peptides.…”

“…At α-LA concentrations >3 % and in the presence of calcium, long tubular structures with diameters of about 20 nm can be obtained. At lower α-LA concentrations, linear fibrils with diameters of 5 nm or random aggregates are produced (Kamau et al 2010). α-LA nanotubes are very stable and due to their long linear structure can be used as viscosifying agents (Kaya-Celiker and Mallikarjunan 2012).…”

Proteolytic Digestion and TiO2Phosphopeptide Enrichment Microreactor for Fast MS Identification of Proteins

“…While this is an outcome of incomplete enzymatic digestion, the presence of such peptides results in a more complete amino acid sequence coverage, and a more reliable identification by MS. α-Lactalbumin could not be identified in any of the experiments conducted using the microreactor. Although it has a relatively small molecular weight (~16 kDa), its globular structure and the lack of a protein denaturing step led most likely to resisting proteolytic digestion with trypsin [35,36]. The performance of the microreactor compared with overnight digestion in terms of unique peptides and % amino acid sequence coverage, is provided in Figure 2, and shown as a range for three replicate Figure 1 experiments.…”