Raj Krishnan Chandra, Talarico Lee A, Ingram Lonnie O, Maupin-Furlow Julie A
Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611-0700, USA.
Appl Environ Microbiol. 2002 Jun;68(6):2869-76. doi: 10.1128/AEM.68.6.2869-2876.2002.
Pyruvate decarboxylase (PDC) is the key enzyme in all homo-ethanol fermentations. Although widely distributed among plants, yeasts, and fungi, PDC is absent in animals and rare in bacteria (established for only three organisms). Genes encoding the three known bacterial pdc genes have been previously described and expressed as active recombinant proteins. The pdc gene from Zymomonas mobilis has been used to engineer ethanol-producing biocatalysts for use in industry. In this paper, we describe a new bacterial pdc gene from Zymobacter palmae. The pattern of codon usage for this gene appears quite similar to that for Escherichia coli genes. In E. coli recombinants, the Z. palmae PDC represented approximately 1/3 of the soluble protein. Biochemical and kinetic properties of the Z. palmae enzyme were compared to purified PDCs from three other bacteria. Of the four bacterial PDCs, the Z. palmae enzyme exhibited the highest specific activity (130 U mg of protein(-1)) and the lowest Km for pyruvate (0.24 mM). Differences in biochemical properties, thermal stability, and codon usage may offer unique advantages for the development of new biocatalysts for fuel ethanol production.
丙酮酸脱羧酶（PDC）是所有同型乙醇发酵中的关键酶。尽管PDC广泛分布于植物、酵母和真菌中，但在动物中不存在，在细菌中也很罕见（仅在三种生物中发现）。先前已经描述了编码三种已知细菌pdc基因的基因，并将其表达为活性重组蛋白。运动发酵单胞菌的pdc基因已被用于构建工业上用于生产乙醇的生物催化剂。在本文中，我们描述了来自棕榈发酵杆菌的一种新的细菌pdc基因。该基因的密码子使用模式与大肠杆菌基因的模式非常相似。在大肠杆菌重组体中，棕榈发酵杆菌PDC约占可溶性蛋白的1/3。将棕榈发酵杆菌酶的生化和动力学特性与来自其他三种细菌的纯化PDC进行了比较。在这四种细菌PDC中，棕榈发酵杆菌酶表现出最高的比活性（130 U mg蛋白-1）和最低的丙酮酸Km值（0.24 mM）。生化特性、热稳定性和密码子使用方面的差异可能为开发用于燃料乙醇生产的新型生物催化剂提供独特优势。
