Purification and characterization of a flavor-related enzyme, γ-glutamyl-transpeptidase, from Toona sinensis leaves. Issue 6 (1st November 2016)

• Record Type: Journal Article
• Authors: Liu, Chang-Jin; Jia, Jian-Ying; Wang, Hao-Yu; Xue, Li-Li; Kong, Yu; Wang, Fu-Xin
• Is Part Of: Journal of horticultural science & biotechnology. Volume 91:Issue 6(2016)
• Page Start: 611
• Page End: 618
• Publication Date: 2016-11-01
• Subjects: Toona sinensis -- ɣ-glutamyl-transpeptidase -- gel filtration chromatography -- LC-MS -- flavor precursor; Horticulture -- Periodicals; Plant biotechnology -- Periodicals; Biotechnology -- Periodicals; Biotechnology; Horticulture; Plant biotechnology; Periodicals; 635.05
• DOI: 10.1080/14620316.2016.1206455
• Languages: English
• ISSNs: 1462-0316

Abstract

ABSTRACT: A flavor-related enzyme from Toona sinensis (TS), ɣ-glutamyl-transpeptidase (GGT), was purified 40.67-fold with 13.40% recovery using ammonium sulfate precipitation, dialysis and gel filtration chromatography. Gel filtration chromatography and sodium dodecyl sulfate acryl amide gel electrophoresis (SDS-PAGE) revealed that GGT was a heterodimer with a molecular weight of 90 kDa, and the molecular size of its two subunits was 26 kDa and 64 kDa, respectively. The apparent Km and Vmax of GGT were 3.623 μmol/mL and 2.831 μmol/mL/min of protein, respectively. The optimum reaction temperature was 60°C, while the optimum pH was 7.0. GGT can tolerate temperatures of 70°C for a short time and can keep stable activity at 60°C for more than 2 hours. The effect of metal ions on GGT activity showed that Cu 2+ and Zn 2+ had strong inhibition, while Fe 3+ had strong activation, and other metal ions had only a slight effect. LC-MS analysis indicated that GGT catalyzed (S, S)-γ-glutamyl-(cis-S-1-propenyl)-thioglycine, a flavor precursor found in TS, to release glutamic acid moiety.