Kluyveromyces marxianus protein hydrolysates were prepared by two different sonicated-enzymatic (trypsin and chymotrypsin) hydrolysis treatments to obtain antioxidant and ACE-inhibitory peptides. Trypsin and chymotrypsin hydrolysates obtained by 5 h, exhibited the highest antioxidant and ACE-inhibitory activities. After fractionation using ultrafiltration and reverse phase high performance liquid chromatography (RP-HPLC) techniques, two new peptides were identified. One fragment (LL-9, MW = 1180 Da) with the amino acid sequence of Leu-Pro-Glu-Ser-Val-His-Leu-Asp-Lys showed significant ACE inhibitory activity (IC = 22.88 μM) while another peptide fragment (VL-9, MW = 1118 Da) with the amino acid sequence of Val-Leu-Ser-Thr-Ser-Phe-Pro-Pro-Lys showed the highest antioxidant and ACE inhibitory properties (IC = 15.20 μM, 5568 μM TE/mg protein). The molecular docking studies revealed that the ACE inhibitory activities of VL-9 is due to interaction with the S2 (His513, His353, Glu281) and S'1 (Glu162) pockets of ACE and LL-9 can fit perfectly into the S1 (Thr345) and S2 (Tyr520, Lys511, Gln281) pockets of ACE.

Available online A B S T R A C TYeast protein hydrolysate may be considered as a good source of bioactive peptides. Yeast hydrolysate was prepared by two different physical-enzymatic and autolysis treatments to identify the most active angiotensin I-converting enzyme (ACE) inhibitory and antioxidant peptides. The most active hydrolysate was obtained after sonication-trypsin hydrolysis. The hydrolysate was subjected to fractionation by ultrafiltration. Fraction with molecular weight of <3 kDa exhibited the highest activity. Reverse phase high performance liquid chromatography (RP-HPLC) resolved this fraction into five fractions, one of which (fraction F3) with amino acid sequence of Tyr-Gly-Lys-Pro-Val-Ala-Val-Pro-Ala-Arg (MW:1057.45 Da) exhibited ACE inhibitory (IC50 = 0.42 ± 0.02 mg/ml) and antioxidant activities (26.25 ± 0.13 µM TE/µg protein). Taken together, the results of this study show that S. cerevisiae proteins contain specific peptides in their sequences which can be released by enzymatic hydrolysis. These peptides have excellent bioactive properties that can potentially replace the antioxidant and antihypertensive agents with chemical origin.

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Protein/peptide-based hydrogel biomaterial inks with the ability to incorporate various cells and mimic the extracellular matrix’s function are promising candidates for 3D printing and biomaterials engineering. This is because proteins contain multiple functional groups as reactive sites for enzymatic, chemical modification or physical gelation or cross-linking, which is essential for the filament formation and printing processes in general. The primary mechanism in the protein gelation process is the unfolding of its native structure and its aggregation into a gel network. This network is then stabilized through both noncovalent and covalent cross-link. Diverse proteins and polypeptides can be obtained from humans, animals, or plants or can be synthetically engineered. In this review, we describe the major proteins that have been used for 3D printing, highlight their physicochemical properties in relation to 3D printing and their various tissue engineering application are discussed.

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