Some visceral proteases of albacore tuna fish (Thunnus alalunga)
摘要：
The proteolytic enzymes in the visceral organs of albacore tunafish (Thunnus alalunga) were studied, initially as an extract of thewhole viscera, then as extracts of the individual organs. Preliminarystudies indicated three pH optima of activity in the whole visceraextracts pH 1.7, 3.1-3.5 and 9.5. Analysis of extracts of the individualorgans revealed the alkaline proteolytic activity was present in theintestine and the pyloric caeca, with the pyloric caeca showing thehighest activity. The stomach extract demonstrated high proteaseactivity at pH 1.7 and 3.5, while the remaining organs had relativeactivities at least ten times lower at these pH values.The extract obtained from pyloric caeca was studied in more detail.The approximate levels of trypsin-1ike and chymotrypsin-like activitieswere measured, and the effects of three inhibitors, phenylmethylsulfonylfluoride(PMSF), l-chloro-3-tosylamido-7-amino-L-2-heptanone (TLCK) andL-1-tosylamide-2-phenylethylchloromethylketone (TPCK), determined.Cationic discontinuous polyacrylamide gel electrophoresis coupled with asubstrate inclusion technique for localization of the separated proteasesof the pyloric caeca extract revealed the presence of ten proteolytic enzymes. One was active in acid solution (ca. pH 4) and was inhibitedby PMSF and TLCK. The remaining nine proteases were active at pH 8.0.Five of the alkaline proteases were serine proteases and one of theseshowed trypsin-like specificity including PMSF and TLCK inhibitionand activity against BANA. None of the electrophoretically separatedproteases showed specificities similar to chymotrypsin.
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DOI：
http://hdl.handle.net/1957/27019
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年份：
1976
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