ABSTRACT
The angiotensin I-converting enzyme (ACE) inhibiting activity of bovine plasma hydrolyzates obtained by Alcalase 2.4 L at different degrees of hydrolysis (DH) was evaluated. For the evaluation of ACE inhibition (ACEI), Hippuryl-His-Leu was used as substrate and the amount of hippuric acid liberated by non-inhibiting ACE was determined by spectrophotometry at 228 nm. The results showed that the enzymatic hydrolysis increased the ACEI activity as compared with the un-hydrolyzed plasma. The highest activity was onbtained with a DH of 6.7%. The peptide fractions with the maximum activity were isolated using ultrafiltration membranes, ion exchange chromatography and high performance liquid chromatography on reverse phase (RP-HPLC). The fraction with highest ACEI activity, showed an IC50 of 0.18 mg/mL and contained peptides with sequences AGATGVTISGAG, YSRRHPEYAVS, Q(K)AW and L(l)I(I)VR, which were determined by MALDI-TOF-TOF. It was also found that after submitting such fraction to digestive conditions in vitro, the ACEI activity remained constant.
ABSTRACT
Objective To isolate new conotoxins of Conus textile from the South China Sea,provide new conopeptides for drug discovery and design, and investigate the effects of living environment on toxin secretion by comparing the compositions of the conotoxins of this species from different areas. Methods Crude conotoxins were purified by Sephadex G-25 and RP-HPLC, the amino acid sequences of the purified peptides were determined. Results More than 10 conotoxins were isolated from Conus textile, 4 conotoxins were firstly isolated and 6 conotoxins had the similar sequence as the reported peptides. Conclusion Many M-family conotoxins were isolated from Conus textile, the main compositions of the venom of Conus textile from the South China Sea were similar to those from Cebu and Marinduquc island in Philippines.