PMID: 6412680Jul 1, 1983Paper

Physical and kinetic properties of a plasma-membrane-bound beta-D-glucosidase (cellobiase) from midgut cells of an insect (Rhynchosciara americana larva)

The Biochemical Journal
C Ferreira, W R Terra

Abstract

The midgut caecal cells from Rhynchosciara americana larvae possess a plasma-membrane-bound beta-D-glucosidase (cellobiase, EC 3.2.1.21), which is recovered (75-95%) in soluble form both after treatment with Triton X-100 and after treatment with papain. The Triton X-100-solubilized beta-D-glucosidase displays Mr106000 and pI 5.4, whereas the papain-released beta-D-glucosidase shows Mr65000 and pI 4.7. Thermal inactivations of the detergent-solubilized and the papain-released forms of beta-D-glucosidase both follow apparent first-order kinetics with similar half-lives. The papain-released beta-D-glucosidase, after being purified by density-gradient centrifugation, hydrolyses beta-D-glucosides, beta-D-galactosides and beta-D-fucosides at the same active site, as inferred from experiments of competition between substrates. The beta-D-glucosidase seems to operate in accordance with rapid-equilibrium kinetics, since the Km (0.61 mM) for the enzyme is constant over a wide range of pH. The hydrolysis of the beta-D-glucosidic bond catalysed by the beta-D-glucosidase occurs without inversion of configuration, delta-gluconolactone is a strong (Ki 0.5 microM) inhibitor of the enzyme and substituents in the substrate aglycone affect the ca...Continue Reading

Citations

Mar 26, 2016·Frontiers in Physiology·Ali ShariflooKhalil Talebi Jahroumi
Nov 30, 2014·Applied Biochemistry and Biotechnology·Bahaderjeet SinghAmarjeet Kaur
Jun 23, 2005·Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology·Gyeong Min ByeonByung Rae Jin
Sep 28, 2020·Pesticide Biochemistry and Physiology·Marziyeh OftadehAsgar Ebadollahi
May 22, 2002·Insect Biochemistry and Molecular Biology·J Pontoh, N H Low
Dec 3, 2002·Insect Biochemistry and Molecular Biology·Tamara R AzevedoClélia Ferreira

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