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Milk-clotting mechanism of Dregea sinensis Hemsl. protease.
- Source :
-
Journal of Dairy Science . Dec2015, Vol. 98 Issue 12, p8445-8453. 9p. - Publication Year :
- 2015
-
Abstract
- Dregea sinensis Hemsl. is used as a milk coagulant to produce goat milk cakes in Yunnan, China. However, the composition of milk-clotting compounds and the related mechanism have not been reported. Crude protease was extracted from the stem, purified, and then separated with a Millipore ultrafiltration centrifuge tube. Cysteine protease (procerain B) was identified as the main milk-clotting protein through electrospray ionization mass spectrometry, and its molecular weight was 23.8 kDa. The protease can partially degrade α-casein (CN) and completely degrade β- and κ-CN, and κ-CN degradation resulted in milk clotting. The molecular weight and AA sequence of the peptide fractions were determined through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and a peptide sequencer, respectively. The enzyme cleaved κ-CN at Ala90-Gln91 and produced deputy κ-CN and caseinomacropeptide with molecular weights of 12 and 6.9 kDa, respectively. This cleavage site differed from the majority of chymosins cleaved at Phe105-Met106. [ABSTRACT FROM AUTHOR]
- Subjects :
- *PROTEOLYTIC enzymes
*GOAT milk
*CASEINS
*MILK proteins
*COAGULANTS
Subjects
Details
- Language :
- English
- ISSN :
- 00220302
- Volume :
- 98
- Issue :
- 12
- Database :
- Academic Search Index
- Journal :
- Journal of Dairy Science
- Publication Type :
- Academic Journal
- Accession number :
- 110739906
- Full Text :
- https://doi.org/10.3168/jds.2015-9851