241
sequencing. Also other techniques have been used in combination with MS for
peptide identification (Agrawal et al. 2016, 2017). For example, MALDI MS is
frequently used without any upstream fractionation or any real separation. In certain
cases, HPLC coupled with MS/MS or high-resolution MS has been used for the
identification.
In some cases, HPLC coupled with MS/MS or high-resolution MS is used, and
sequences are provided for the peptides in selected fractions or in the whole hydrolysate. It has also been combined with traditional identification methods, like in the
study of Pihlanto et al. (2010) where ACE-inhibitory peptides in fermented milk
were identified using matrix-assisted laser desorption ionization-time of flight
(MALDI-TOF) and Edman degradation sequencing. MS equipment has advantages
like sensitive and accurate mass information, with a short-term analysis (D’siva and
Mine 2010).
Electrospray (ESI), a type of ionization source, has displaced previous ionization
methodology like fast atom bombardment (del Mar Contreras et al. 2008; SanchezRivera et al. 2014). Also, MS coupled with on-line HPLC has allowed discovery of
antihypertensive peptides from peptic digestion of lactoferrin (Ruiz-Gimenez et al.
2012). This study used ESI as ionization source and ion trap mass analyzer (IT).
Another implementation of ESI was in characterization of bioactive peptides in
infant milk formulas where two mass analyzers (ESI-IT and ESI-TOF) were used
(Catala-Clariana et al. 2010). MALDI is another type of ionization source that is
employed in identification of longer peptides and has some advantages over ESI:
higher sensitivity, lower susceptibility to impurities and single charged ions.
However, MALDI does not permit on-line chromatographic coupling like ESI does
(Mamone et al. 2009). Table 1 shows some examples where MALDI presented with
TOF (MALDI-TOF) was used to identify peptides, like antimicrobial activity of
peptic hydrolysate from lactoferrin (Chan and Li-Chan 2007).
Processing of Bioactive Peptides
Industrial scale production of bioactive peptides in sufficient amounts for human
trials involves various purification and concentration steps. This can lead to changes
in the structure of peptides as well as alter how the peptides interact with surrounding matrix, which will consequently influence the bioavailability and activity of
peptides. Moreover, the products used in experiment to generate peptides may have
the presence of unknown compounds that could affect peptide activity and may give
rise to side effects (Bougle and Bouhallab 2017). Lastly, it is reported that storage
can shorten the shelf-life of peptides and modify their bioavailability (Rao et al.
2012). Thus, care must be taken when industrial process of producing bioactive
peptides is carried out.
Bioactive Peptides Derived from Different Sources
sequencing. Also other techniques have been used in combination with MS for
peptide identification (Agrawal et al. 2016, 2017). For example, MALDI MS is
frequently used without any upstream fractionation or any real separation. In certain
cases, HPLC coupled with MS/MS or high-resolution MS has been used for the
identification.
In some cases, HPLC coupled with MS/MS or high-resolution MS is used, and
sequences are provided for the peptides in selected fractions or in the whole hydrolysate. It has also been combined with traditional identification methods, like in the
study of Pihlanto et al. (2010) where ACE-inhibitory peptides in fermented milk
were identified using matrix-assisted laser desorption ionization-time of flight
(MALDI-TOF) and Edman degradation sequencing. MS equipment has advantages
like sensitive and accurate mass information, with a short-term analysis (D’siva and
Mine 2010).
Electrospray (ESI), a type of ionization source, has displaced previous ionization
methodology like fast atom bombardment (del Mar Contreras et al. 2008; SanchezRivera et al. 2014). Also, MS coupled with on-line HPLC has allowed discovery of
antihypertensive peptides from peptic digestion of lactoferrin (Ruiz-Gimenez et al.
2012). This study used ESI as ionization source and ion trap mass analyzer (IT).
Another implementation of ESI was in characterization of bioactive peptides in
infant milk formulas where two mass analyzers (ESI-IT and ESI-TOF) were used
(Catala-Clariana et al. 2010). MALDI is another type of ionization source that is
employed in identification of longer peptides and has some advantages over ESI:
higher sensitivity, lower susceptibility to impurities and single charged ions.
However, MALDI does not permit on-line chromatographic coupling like ESI does
(Mamone et al. 2009). Table 1 shows some examples where MALDI presented with
TOF (MALDI-TOF) was used to identify peptides, like antimicrobial activity of
peptic hydrolysate from lactoferrin (Chan and Li-Chan 2007).
Processing of Bioactive Peptides
Industrial scale production of bioactive peptides in sufficient amounts for human
trials involves various purification and concentration steps. This can lead to changes
in the structure of peptides as well as alter how the peptides interact with surrounding matrix, which will consequently influence the bioavailability and activity of
peptides. Moreover, the products used in experiment to generate peptides may have
the presence of unknown compounds that could affect peptide activity and may give
rise to side effects (Bougle and Bouhallab 2017). Lastly, it is reported that storage
can shorten the shelf-life of peptides and modify their bioavailability (Rao et al.
2012). Thus, care must be taken when industrial process of producing bioactive
peptides is carried out.
Bioactive Peptides Derived from Different Sources