This investigation was conducted to differentiate the esterases
in a water extract of freeze-dried green beans on the basis of inhibitor
and substrate specificities. An attempt was made to classify
these esterases according to the criteria used for animal esterases.
Activity of the esterases was measured manometrically using
the Gilson differential respirometer. Aqueous extracts of green
beans were found to hydrolyze the acetyl, propionyl, and n-butyryl
esters of glycerol, phenol, and 2-naphthol-6-SO₃Na. No hydrolysis
of triolein or long-chain 2-naphthol-6-SO₃Na esters was noted, indicating
the absence of lipases. A small amount of activity was observed
when the choline esters served as substrates, but this was
attributed to esterases other than cholinesterases. Optimum activity
of the extract on triacetin, tripropion, tributyrin, phenyl acetate,
and phenyl propionate occurred at pH 7.2.
The effects of organophosphorus inhibitors, diethyl p-nitrophenyl
thiophosphate, tetraethyl pyrophosphate, and diisopropylphosphorofluoridate,
at concentrations ranging from 10⁻¹ M to
10⁻¹⁰ M on the esterase activity was studied. These data show that
the green bean extract contains at least three esterases. One was
resistant to certain organophosphorus compounds, suggesting similarity
to animal arylesterases (aryl ester hydrolase, EC 3.1.1.2).
Various concentrations of organophosphorus compounds inhibited the
activity of the two other esterases. These were classified as carboxylesterases
(carboxylic ester hydrolase, EC 3.1.1.1). / Graduation date: 1968
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26803 |
| Date | 08 March 1968 |
| Creators | Putnam, Teryl Beebe |
| Contributors | Montgomery, Morris W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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