Substrate and inhibitor specificities have been used to classify
esterases. The purpose of this work was to determine the substrate
and inhibitor specificities of the esterases in an aquous extract of
lyophilyzed carrots.
Esterase activity was determined manometrically at 37°C. The
optimum pH of the carrot esterases with several substrates varied
from 6.8 to 7.2, and a pH of 7.2 was used in this study. The carrot
extract hydrolyzed acetyl, propionyl and butyryl esters of phenol,
2-naphthol-6-SO₃Na and glycerol. As the acyl chain length was
increased, activity decreased. Long-chain naphthyl esters and
triolein were not hydrolyzed, which suggested the absence of lipase
in the extract. Lack of activity with choline esters indicated the
absence of cholinesterases. EDTA did not exhibit appreciable
activation of carrot esterases.
The effect of parathion, diisopropyl phosphorofluoridate (DFP) and tetraethyl pyrophosphate (TEPP) at various concentrations on the
rate of hydrolysis of the acetyl, propionyl and butyryl esters, of
phenol, 2-naphthol-6-SO₃Na and glycerol indicated the presence of
six esterases. Inhibitor and substrate specificities of five
esterases were similar to carboxylesterases (EC 3.1.1.1). The
sixth esterase was similar to arylester as e (EC 3.1.1.2). An enzyme
hydrolyzing DFP and TEPP was suggested in the carrot extract. / Graduation date: 1968
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26804 |
| Date | 14 December 1967 |
| Creators | Carino, Lourminia Almeda |
| Contributors | Montgomery, Morris W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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