Bioactive Proteins and Peptides from Food Sources. Applications of Bioprocesses used in Isolation and Recovery

Abstract

There are many examples of biologically active food proteins, with physiological significance beyond the pure nutritional requirements that concern available nitrogen for normal growth and maintenance. Moreover, there are many physiologically active peptides, derived by protease activity from various food protein sources; however, relationships between structural properties and functional activities have not been completely elucidated. Many bioactive peptides have in common structural properties that include a relatively short peptide residue length (e.g. 2-9 amino acids), possessing hydrophobic amino acid residues in addition to proline, lysine or arginine groups. Bioactive peptides are also resistant to the action of digestion peptidases. Antihypertensive peptides, known as Angiotensin I converting enzyme (ACE) inhibitors have been derived from milk, corn and fish protein sources. Peptides with opioid activities are derived from wheat gluten or casein, following digestion with pepsin. Exorphins, or opioid peptides derived from food proteins such as wheat and milk (e.g. exogenous sources) have similar structure to endogenous opioid peptides, with a tyrosine residue located at the amino terminal or bioactive site. Immunomodulatory peptides derived from tryptic hydrolysates of rice and soybean proteins act to stimulate superoxide anions (reactive oxygen species-ROS), which triggers non-specific immune defense systems. Antioxidant properties that prevent peroxidation of essential fatty acids have also been shown for peptides derived from milk proteins. The addition of a Leu or Pro residue to the N-terminus of a His-His, dipeptide will enhance antioxidant activity and facilitate further synergy with non-peptide antioxidants (e.g. BHT). We also show herein, that the tryptic digests of casein yielding caseinophosphopeptides exhibits both hydrophilic and lipophilic antioxidant activity due to both metal ion sequestering and quenching of ROS. The separation and purification of bioactive peptides which will involve development of automated and continuous systems is an important field for Food chemists. Much effort has been given to develop selective column chromatography methods that can replace batch methods of salting out, or using solvent extraction to isolate and purify bioactive peptides. Advances here will enable recovery of bioactive peptides with minimal destruction thus enabling utilization by returning these active peptides to functional food or specific nutraceutical applications.

The impact of milk proteins and peptides on blood pressure and vascular function: a review of evidence from human intervention studies

“…Bovine milk contains approximately 31 -33 g protein per litre, of which about 80 % is casein and 20 % is whey protein. Bioactive peptides are specific protein fragments that have been shown to influence physiological functions and, ultimately, health (31) . The activity of these peptides is based on their inherent amino acid composition and sequence.…”

Biotechnological richness of the northeastern semi-arid region: antioxidant activity of casein hydrolysates from Moxotó goat milk (Capra hircus Linnaeus, 1758) obtained by papain action

“…Antioxidant properties of caprine casein hydrolysates under studied conditions refer to the presence of peptides rich in amino acids such as histidine, lysine, proline and tyrosine (KITTS;WEILER, 2003), which were shown in some peptides sequences after sequencing analysis by MALDI-TOF-MS/MS. Moreover, the antioxidant activity of caprine casein hydrolysates can also be related to DH, specificity and origin of the enzyme used in the proteolytic digestion.…”

Immunomodulatory activities of whey β-lactoglobulin tryptic-digested fractions

“…It is known that primary sequences of whey proteins may contain many biologically active peptides, specific short protein fragments that have positive effects on human health apart from their nutritional characteristics (Kitts & Weiler, 2003). These peptides show no effects when contained within the whole protein sequence, but they can be released by enzymatic proteolysis.…”