Application of NMR Spectroscopy for Structural Characterization of Bioactive Peptides Derived from Food Protein

Traditionally, food has not only been the source of human nutrition but also an excellent factor for deriving nutraceuticals and pharmaceuticals. The biopolymers such as protein and polysaccharides derived from food sources have special significance as they are important part of human diet. Several important bioactive peptides have been discovered from food protein hydrolysates and fermented products that have shown to possess a spectrum of beneficial pharmacological activities. This chapter deals with food protein derived bioactive peptides and their structural characterization employing NMR spectroscopy. It is well known from the vast literature on bioactive peptides that NMR spectroscopy is an indispensable tool to fully characterize the structures of bioactive peptides in their inherent physiological state. However, limited literature exists on detailed structural characterization of food derived bioactive peptides. It is therefore very important to review the literature on structural aspects of food peptides and provide an appraisal of NMR techniques suitable for comprehensive structural characterization of this class of bioactive peptides.

This chapter is aimed to introduce NMR spectroscopy and its applications to a wide range of readers in the field of food chemistry in general and to the food peptide researchers in particular. The main objective is to review the literature on food derived bioactive peptides and highlight the potential of NMR spectroscopy to understand structure-activity relationship of bioactive peptides in order to boost further developments in this important field. With a view to make this chapter readable to beginners in the field, basic principles of NMR spectroscopy will also be included.

Application of solution NMR spectroscopy to bioactive peptides will then be described. Salient features including the size and structural differences of food bioactive peptides when compared to the other classes of bioactive peptides will then be discussed in order to make an informed assessment of choice of NMR techniques suitable for their structural characterization.

Keywords: ACE inhibitory peptides, Antimicrobial peptides, Antioxidative peptides, Bioactive peptides, Chemical shift index, Food proteins, Immunomodulatory peptides, Multidimensional NMR Spectroscopy, Nutraceutical value, Secondary structure, Structure activity relationship.