title: Heterologous expression and characterization of tyrosine decarboxylase from Enterococcus faecalis R612Z1 and Enterococcus faecium R615Z1.
abstract: Tyrosine decarboxylase (TDC) is responsible for tyramine production and can catalyze phenylalanine to produce β-phenylethylamine. Enterococcus strains are a group of bacteria predominantly producing tyramine and β-phenylethylamine in water-boiled salted duck. In this study, the heterologous expression and characterization of two TDCs from Enterococcus faecalis R612Z1 (612TDC) and Enterococcus faecium R615Z1 (615TDC) were studied. The recombinant putative proteins of 612TDC and 615TDC were heterologously expressed in Escherichia coli. 612TDC is a 620-amino-acid protein with a molecular mass of 70.0 kDa, whereas 615TDC is a 625-amino-acid protein with a molecular mass of 70.3 kDa. Both 612TDC and 615TDC showed an optimum temperature of 25 °C for the tyrosine and phenylalanine substrates. However, 612TDC revealed maximal activity at pH 5.5, whereas 615TDC revealed maximal activity at pH 6.0. Kinetic studies showed that 612TDC and 615TDC exhibited higher specificity for tyrosine than for phenylalanine. The catalysis abilities of both 612TDC and 615TDC for phenylalanine were restrained significantly with the increase in NaCl concentration, but this was not the case for tyrosine. This study revealed that the enzyme properties of the purified recombinant 612TDC and 615TDC were similar, although their amino acid sequences had 84% identity.
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Xu
authors.affiliation: College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210046, China.
authors.forename: Lihui
authors.initials: L
authors.lastname: Du
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Daoying
authors.initials: D
authors.lastname: Wang
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Yongzhi
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Geng
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors.forename: Muhan
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China. weiminxu2002@aliyun.com.
authors.forename: Weimin
authors.initials: W
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004372:Ducks / Q000382:microbiology; D013293:Enterococcus faecalis / Q000201:enzymology*; D016984:Enterococcus faecium / Q000201:enzymology*; D005511:Food Handling; D005516:Food Microbiology; D007700:Kinetics; D008970:Molecular Weight; D010627:Phenethylamines / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism*; D014439:Tyramine / Q000096:biosynthesis; D014445:Tyrosine Decarboxylase / Q000235:genetics / Q000378:metabolism*
chemical_list: D010627:Phenethylamines; D011994:Recombinant Proteins; C029261:phenethylamine; D014445:Tyrosine Decarboxylase; D014439:Tyramine