Abstract
The inhibition of the enzyme dipeptidyl-peptidase IV (DPP-IV) is an effective pharmacotherapeutic approach for the management of type 2 diabetes. Recent findings have suggested that dietary proteins, including bovine α-lactalbumin, could be precursors of peptides able to inhibit DPP-IV. However, information on the location of active peptide sequences within the proteins is far from being comprehensive. Moreover, the traditional approach to identify bioactive peptides from foods can be tedious and long. Therefore, the objective of this study was to use peptide arrays to screen α-lactalbumin-derived peptides for their interaction with DPP-IV. Deca-peptides spanning the entire α-lactalbumin sequence, with a frame shift of 1 amino acid between successive sequences, were synthesized on cellulose membranes using “SPOT” technology, and their binding to and inhibition of DPP-IV was studied. Among the 114 α-lactalbumin-derived decamers investigated, the peptides 60WCKDDQNPHS69 (αKi = 76 µM), 105LAHKALCSEK114 (Ki = 217 µM) and 110LCSEKLDQWL119 (Ki = 217 µM) were among the strongest DPP-IV inhibitors. While the SPOT- and traditionally-synthesized peptides showed consistent trends in DPP-IV inhibitory activity, the cellulose-bound peptides’ binding behavior was not correlated to their ability to inhibit the enzyme. This research showed, for the first time, that peptide arrays are useful screening tools to identify DPP-IV inhibitory peptides from dietary proteins.
Highlights
Dietary proteins are known to be instrumental in a wide range of nutritional and biological processes [1].Over the last two decades, a growing body of research has shown that they can be precursors of an array of biologically active peptides that have the potential to improve human health [2]
Peptides derived from dietary proteins have not yet been shown to prevent the degradation of the incretins in vivo, the discovery of their ability to inhibit the activity of the dipeptidyl-peptidase IV (DPP-IV) enzyme in vitro has triggered great interest in the bioactive peptide research area
DPP-IV revealed that a number of α-lactalbumin-derived peptides are able to interact with the enzyme
Summary
Dietary proteins are known to be instrumental in a wide range of nutritional and biological processes [1].Over the last two decades, a growing body of research has shown that they can be precursors of an array of biologically active peptides that have the potential to improve human health [2]. Even though bioactive peptides have been found encrypted in the sequence of a number of proteins from both plant and animal sources, milk proteins are currently considered the most important precursors of peptides with biological activities [3]. In addition to containing protein fragments with anti-hypertensive, anti-bacterial, anti-cariogenic, anti-oxidative, mineral binding, opioid and immunomodulating activities [4,5,6], dietary proteins, whey proteins, have recently been found to contain within their sequence peptides able to inhibit the activity of the enzyme dipeptidyl-peptidase IV (DPP-IV) in vitro [7,8,9,10,11,12,13,14,15]. Peptides derived from dietary proteins have not yet been shown to prevent the degradation of the incretins in vivo, the discovery of their ability to inhibit the activity of the DPP-IV enzyme in vitro has triggered great interest in the bioactive peptide research area
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