کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2435293 | 1107066 | 2008 | 9 صفحه PDF | دانلود رایگان |
This study determined specificities of aminopeptidase N (PepN), endopeptidase E (PepE), endopeptidase O (PepO), endopeptidase O2 (PepO2), and endopeptidase O3 (PepO3), from Lactobacillus helveticus WSU19 on the αs1-CN f1-23 peptide, formed by residual chymosin during cheese ripening. Cell-free extracts (CFEs) were prepared from Escherichia coli DH5α derivatives expressing peptidase genes of Lb. helveticus WSU19. The αs1-CN f1-23 peptide was digested by CFEs under cheese ripening conditions. Degradation pattern was analyzed qualitatively using MALDI-TOF mass spectrometry. PepN exhibited activity on αs1-CN f1-23 only in the presence of an endopeptidase, particularly PepO-like endopeptidases. PepO, PepO2, and PepO3 cleaved αs1-CN f1-23 predominantly at Glu14–Val15, forming the bitter peptide αs1-CN f1-14. PepE cleaved αs1-CN f1-23 primarily at Lys3–His4, suggesting a role for PepE in degrading bitter peptides from the N-terminus of αs1-CN f1-23. Combinations of PepE/PepO and PepE/PepO2 were determined to have the potential to decrease the accumulation of αs1-CN f1-14.
Journal: International Dairy Journal - Volume 18, Issue 2, February 2008, Pages 178–186