**1. Introduction**

Proteins or bioactive active substance-made drugs have become an integral class of therapeutics serving as auspicious alternatives to treat many diseases that have till now proven recalcitrant to treatment [1]. The nutritional benefits of root vegetables are no longer in doubt nowadays as they are known to be bioactive proteins making them one of the heartiest and healthiest foods around with therapeutic benefits. Hence, they essentially serve as an alternative protein source rich in phytochemicals such as polyphenols, carotenoids, etc. This among other reasons which are environmental and physiological has made an increasing number of people now include one root vegetable or the other in their staple food [2, 3]. The burden of necessity is been placed on the increasing demand for proteins, especially those from plants and in particular root vegetables. This is owing to the growing world's population which

stands at around 6.5 billion and is expected to double by the year 2063. This increased demand for root vegetable protein is further corroborated statistically as two-thirds of the planet's dietary protein comes from vegetables [4]. There exist a broad range of biological activities exhibited by bioactive proteins, and these activities are responsible for their application and interest in foods, supplements, and medicine [5].

The tremendous attention bioactive proteins have gained over the years is not unconnected with their disease prevention and treatment ability, which is owing to their multi-target health benefits. To this end, it becomes imperative to know their distinctive functionalities by separating them from their natural matrices and carrying out their characterization. This separation brings about the unfolding of their functional groups, which interact with target tissues [6]. For scientists to have a deeper understanding of such (potential or already established) therapeutic candidates' biomolecular mechanisms and interactions, biophysical and biochemical characterization of specific quality and functions becomes imperative. This is as characterization provides information in respect of identity (structure), purity, potency, safety, and stability. Also, these characterizations give insight and understanding into some of the compelling parameters essential for the maintenance of protein's activity as well as the conformation of the higher-order structure (HOS). These HOS include the tertiary structure (3-dimensional structure), secondary structure (protein's folding), and quaternary structure (sub-unit association) [7]. The increasing significance of biophysical analysis in the characterization of therapeutics such as bioactive proteins stems from the fact that it enhances the investigation and characterization of such biomolecules using physical techniques [8]. A typical characterization technique employed or carried out by researchers looked at the various structural make-up, functionalities, and stability of a bioactive protein. This is because they have varying degrees of implications as they affect the bioactivity of such bioactive proteins.

These physical techniques employed circular dichroism (CD), Fouriertransmission infrared (FTIR), spectroscopy, differential scanning calorimetry (DSC), intrinsic and extrinsic fluorescence, and dynamic light scattering, among others to elucidate their spectroscopic, thermodynamic, and hydrodynamic parameters [9–11]. The significance of a biochemical assay or characterization stems from the fact that this approach helps detect, quantify, and or study biological molecules such as bioactive protein's binding or activity [12].

### **2. Root vegetables bioactive proteins**

Food proteins, particularly root vegetable bioactive proteins, generally now have scientific bases to be regarded as having nutritional and physiological functionalities, regulated by some encrypted peptides in their native protein sequence [13]. Carrot (*Daucus carota* L,), onion (*Allium cepa* L,), and lettuce (*Lactuca sativa*), among others, are globally seen as belonging to the most common root vegetables which are known to have specialized. Although these compounds or molecules are secondary metabolites that do not contribute to the root vegetables' vital process, they are however beneficial to many living organisms on health grounds [2]. These molecules or compounds which herein are referred to as bioactive proteins will at one time or the other need to be purified, compounded, and stored by targeting the biophysical properties of these bioactive proteins [14]. Root vegetables' bioactive proteins vary in the bioactive compound from one root vegetable to the other with some conferring characteristic color, taste, etc. For example, while carrot's (*D. carota* L,) characteristic *Principles of Biophysical and Biochemical Characterization of Root Vegetables' Bioactive Proteins DOI: http://dx.doi.org/10.5772/intechopen.107986*

orange color is largely due to the β-carotene presence in it, onion's (*A. cepa* L,) antioxidant, anti-inflammatory, and antimicrobial properties on the other hand have been linked to the presence of biologically active phytochemicals such as flavonoids, etc. [15]. Potato (*Solanum tuberosum* L,) as a root vegetable is also rich in bioactive phytochemicals such as β-carotene or carotenoids, ascorbic acids, polyphenols, and natural phenols among others, which determine the color of the potato's skin and pulp [16].
