Purification and Characterisation of Endopeptidase Produced by Lactococcus Lactis Subsp. Lactis RI 11
In the this study, 10 isolates of Lactic Acid Bacteria (LAB) were isolated from ikan rebus (steam fish) purchased from a local market, was characterised by phenotypical and biochemical characteristics. Eight isolates were identified as Lactococcus lactis subsp. lactis and were evaluated for endop...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2001
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/8443/1/FSMB_2001_16_IR.pdf |
| Summary: | In the this study, 10 isolates of Lactic Acid Bacteria (LAB) were isolated from
ikan rebus (steam fish) purchased from a local market, was characterised by
phenotypical and biochemical characteristics. Eight isolates were identified as
Lactococcus lactis subsp. lactis and were evaluated for endopeptidase activity. As
the endopeptidase activity of the crude cell extracts varied among isolates, only
Lc. lactis subsp. lactis RI 11 was selected for further study. The optimum
endopeptidase activity was at pH 7.5 and 45°C. The crude enzyme preparation
was purified to apparent homogeneity by ammonium sulphate fractionation, muon
and cation exchange chromatography and gel filtration chromatography. The purification procedure has resulted 1.55% yield and 2.36 purification fold. As the
purified endopeptidase has 3 optimum temperatures (10°C, 50°C and 90°C) and
pH (3.5, 6.5 and 9.5), it was likely that the endopeptidase consist more than one
isoenzymes. The molecular mass of purified endopeptidase was approximately
14.15 kDa estimated with Sodium dodecyl sulphate-polyacrylamide gel
electrophoresis analysis. However, a lower molecular mass of 3.9 kDa was
obtained from gel filtration chromatography. In terms of substrate specificity, the
purified endopeptidase showed higher substrate affinity towards bradykinin with a
K.m value of 0.029 mM, whilst, oxidised insulin B chain demonstrated the highest
production rate with the Vmax value of 10.52. |
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