Inglese J, Johnson D L, Shiau A, Smith J M, Benkovic S J
Department of Chemistry, Pennsylvania State University, University Park 16801.
Biochemistry. 1990 Feb 13;29(6):1436-43. doi: 10.1021/bi00458a014.
Glycinamide ribonucleotide transformylase (GAR TFase; EC 2.1.2.2) has been purified 70-fold to apparent homogeneity from Escherichia coli harboring an expression vector encoding the purN gene product, GAR TFase. The protein is a monomer of Mr 23,241 and catalyzes a single reaction. Steady-state kinetic parameters for the enzyme have been obtained. The structural requirements for cofactor utilization have been investigated and found to parallel those of the multifunctional avian enzyme. The enzyme was inactivated with the affinity label N10-(bromoacetyl)-5,8-dideazafolate in a stoichiometric and active-site-specific manner. The ionization state of the cofactor analogue in the enzyme-cofactor complex appears to require the dissociation of the proton at N3 of the pyrimidine within the complex.
甘氨酰胺核糖核苷酸转甲酰基酶（GAR TFase；EC 2.1.2.2）已从携带编码purN基因产物GAR TFase的表达载体的大肠杆菌中纯化了70倍，达到明显的均一性。该蛋白质是一个分子量为23241的单体，催化单一反应。已获得该酶的稳态动力学参数。对辅因子利用的结构要求进行了研究，发现与多功能禽类酶的要求相似。该酶被亲和标记物N10-（溴乙酰基）-5,8-二去氮叶酸以化学计量和活性位点特异性的方式灭活。酶-辅因子复合物中辅因子类似物的电离状态似乎需要复合物中嘧啶N3位的质子解离。
