Abstract
L-Glutamate decarboxylase, an enzyme under the control of the asexual developmental cycle of Neurospora crassa, was purified to homogeneity from conidia. The purification procedure included ammonium sulfate fractionation and DEAE-Sephadex and cellulose phosphate column chromatography. The final preparation gave a single band on sodium dodecyl sulfate-polyacrylamide gels with a molecular weight of 33,200 +/- 200. A single band coincident with enzyme activity was found on native 7.5% polyacrylamide gels. The molecular weight of glutamate decarboxylase was 30,500 as determined by gel permeation column chromatography at pH 6.0. The enzyme had an acidic pH optimum and showed hyperbolic kinetics at pH 5.5 with a Km for glutamic acid of 2.2 mM and a Km for pyridoxal-5'-phosphate of 0.04 microM.
Highlights
One enzyme that is stored in dormant conidia is glutamate decarboxylase (GAD,’ E.C.4.1.1.15) ( 5 )
Even though GAD activity is high in dormant conidia, it does not catalyze the metabolism of glutamic acid until germination (5, 6, 8)
This paper is the first report of the purification ofGAD from fungi, and the firstreport of the purification to homogeneity of an intracellular enzyme from N . crassa conidia
Summary
These values were calculated based on the frequency of histidine. b T h e molecular weight of GAD was takenas 33,200 from the results of SDS-PAGE. A unit of GAD activity will catalyze the release of 1pmol of COZ from glutamic acid per min a t 37 “C. Specific activity was defined as unitsof GAD activity per mg of protein
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
