The proteolytic enzymes in the visceral organs of albacore tuna
fish (Thunnus alalunga) were studied, initially as an extract of the
whole viscera, then as extracts of the individual organs. Preliminary
studies indicated three pH optima of activity in the whole viscera
extracts pH 1.7, 3.1-3.5 and 9.5. Analysis of extracts of the individual
organs revealed the alkaline proteolytic activity was present in the
intestine and the pyloric caeca, with the pyloric caeca showing the
highest activity. The stomach extract demonstrated high protease
activity at pH 1.7 and 3.5, while the remaining organs had relative
activities 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 activities
were measured, and the effects of three inhibitors, phenylmethylsulfonylfluoride
(PMSF), l-chloro-3-tosylamido-7-amino-L-2-heptanone (TLCK) and
L-1-tosylamide-2-phenylethylchloromethylketone (TPCK), determined.
Cationic discontinuous polyacrylamide gel electrophoresis coupled with a
substrate inclusion technique for localization of the separated proteases
of the pyloric caeca extract revealed the presence of ten proteolytic enzymes. One was active in acid solution (ca. pH 4) and was inhibited
by PMSF and TLCK. The remaining nine proteases were active at pH 8.0.
Five of the alkaline proteases were serine proteases and one of these
showed trypsin-like specificity including PMSF and TLCK inhibition
and activity against BANA. None of the electrophoretically separated
proteases showed specificities similar to chymotrypsin. / Graduation date: 1976
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27019 |
| Date | 28 April 1976 |
| Creators | Sullivan, Daniel Park |
| Contributors | Montgomery, Morris W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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