# Generation and Characterization of Novel Bioactive Peptides from Fish and Beef Hydrolysates
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & \multicolumn{3}{c}{**IC\({}_{\text{50}}\) (\(\mathrm{\SIUnitSymbolMicro m}\))**} \\ \cline{2-4}  & **ACE** & **Antioxidant** & **TEAC** \\ \hline Fish hydrolysates & 304.5 & 470.4 & 0.14 \\ F21 & 7.3 & 389.9 & 0.17 \\ Beef hydrolysates & 265.6 & 531.0 & 0.12 \\ B34 & 5.8 & negative & negative \\ \hline \hline \end{tabular} IC\({}_{\text{50}}\) was defined as the protein concentration required to inhibit 50\(\%\) ACE for ACE inhibitory activity and to inhibit 50\(\%\) of DPPH radicals for antioxidant activity. TEAC indicates the Trolox equivalent antioxidant capacity obtained with the IC\({}_{\text{50}}\) Trolox/IC\({}_{\text{50}}\) sample.  
\end{table} 
Table 2: ACE inhibitory activity and antioxidant properties of the hydrolysates F21 and B34. E. coli.The antimicrobial activity of peptides generated from meat varies greatly depending on the origin and their primary and secondary structures. The generation and characterization of new ACE inhibitors are required for applications in food and medicine. B34 showed a higher ACE inhibitory action than those reported by [PERSON] and [PERSON] [16]. They reported that ACE inhibitory peptide fractions extracted from beef hydrolysates with IC\({}_{50}\) values ranging from 23.11 to 24.15 \(\upmu\)g/mL. Furthermore, B34 was more potent than an ACE inhibitory peptide (IC\({}_{50}\) 28.5 \(\upmu\)M) generated by digestion of pork with pepsin [33]. On the other hand, the ACE inhibitory activity of peptide fractions obtained after hydrolysis of skin and bone gelatin of catfish by alcalase (IC\({}_{50}\) 3.2 \(\upmu\)g/mL and 1.3 \(\upmu\)g/mL, respectively) were more potent than F21. The amino acid sequence of the peptides with ACE inhibitory activity, the hydrophobic residues containing aliphatic side groups--such as Ile, Gly, Leu, Ala, and Val--at the C-terminus were responsible for enhancing the ACE inhibitory activity due to their increased binding capability with ACE [34]. Furthermore, positively charged residues, such as Arg and Lys, are also implicated in the greater efficacy of ACE inhibitory activity [35]. Additionally, the ACE inhibitory activity of peptides depends on their molecular masses; a study showed that peptides with a molecular mass < 3 kDa displayed greater ACE inhibitory activity than larger peptides [35]. Another general property of ACE inhibitory peptides is the occurrence of hydrophobic amino acid residues at the N-terminals of peptides [36]. B34 has more hydrophobic residues in the N-terminal--including Ala, Leu, and Ile--than the fish peptide, and this illustrates the higher ACE inhibitory activity of the pure beef peptide. However, the precise correlation between the functions of peptides and their structures is still unclear [37]. Free radicals target the main biological compounds, such as DNA, and negatively influence human health, leading to cardiovascular diseases and tumor formation. Utilization of antioxidant peptides derived from natural sources is a promising approach to attenuate the effects of free radicals. F21 exhibited greater antioxidant activity than bioactive peptides derived by enzymatic hydrolysis of tuna head (IC\({}_{50}\) value of 1.34 mg/mL) [38] and an antioxidant peptide derived from a ray gelatin hydrolysate (IC\({}_{50}\) value of 1.98 mg/mL) [39]. The location of the peptide in the protein composition, hydrophobicity, molecular weight, and amino acid sequence influence the antioxidant action of peptides.