## 4 Biological and Health-Promoting Properties of Potato Proteins  
Native potato proteins may also exhibit beneficial non-food properties, such as putative antimicrobial or antitumor [54], as well as antioxidant and antiradical [4; 22; 27; 33; 54; 55; 56; 57]. These authors stated that the proteins of the patatin fraction are active as lipid-acyl hydrolases (LAH) and catalyze non-specific hydrolysis of phospholipids, glycolipids, mono- and diacyl glycerols and esters of long-chain fatty acids. This activity is shown by the hydrolysates of potato proteins. Patatin protein hydrolysates obtained by [PERSON] and [PERSON] [2] from potato pulp using multi-enzymatic systems, particularly with the use of Depol 670 L, were characterized by high lipid acyl hydrolase (LAH) activity. In other studies, patatin proteins obtained in the acidic-based precipitation process showed high activity of LAH towards long-chain fatty acids, while those obtained by thermal/acidic and CMC-based protein isolates did not show such activity [33]. The antioxidant activity of patatin protein hydrolysates is also confirmed by the studies of other authors [17; 52]. They showed that cysteine and tryptophan, as functional groups of patatin proteins, can influence the activity of these protein fractions against radicals. Studies by [PERSON] et al. [57] showed that proteins isolated from potatoes, especially from sprouted tubers, as well as those obtained from by-products of the potato industry, had ACE-inhibitory potencies, and this activity increased as a result of hydrolysis of these proteins and reached IC\({}_{50}\) in the range of 0.018-0.086. The studies of the activity of potato protein fractions showed that patatin fractions were characterized by high antioxidant and antiradical activity. According to [PERSON] et al. [57], native potato protein isolates could be an important raw material for the preparation of bioactive ingredients exhibiting ACE inhibitors and radical scavenging potencies. In other studies, the proteins of the patatin fraction showed antiproliferative activity against mouse melanoma B16 [18]. It is believed that the glycoproteins from the group of heat-resistant lectins present in potatoes are among the proteins with potential allergenicity [9].  
Protease inhibitors play an important role by participating in plant defense mechanisms against the attack of certain microorganisms and insects by neutralizing the proteolytic enzymes secreted by them. The 21 kDa protease inhibitor proteins are believed to have anticarcinogenic activity, and protease inhibitors I and II, potato cysteine protease inhibitor and Kunitz-type inhibitors also show antimicrobial activity [1; 4; 58; 59]. It is all the more important that, among them, there were the two most numerous fractions of inhibitor proteins, i.e., the potato serine protease inhibitors (PSPI) and the potato cysteine protease inhibitors, with a molecular weight of 20.5 and 21.0 kDa, respectively [4; 20; 31; 49]. Additionally, other inhibitory proteins found in potato protein exhibit antimicrobial activity. For example, potato carboxopeptidase and potato cysteine inhibitors have shown to be active in inhibiting the growth of cancer cells and reducing the number of reactive oxygen species [60].