Forato Lucimara A, Doriguetto Antonio C, Fischer Hannes, Mascarenhas Yvonne P, Craievich Aldo F, Colnago Luiz A
Embrapa Instrumentação Agropecuária, Rua XV de Novembro, 1452, São Carlos, SP, Brazil.
J Agric Food Chem. 2004 Apr 21;52(8):2382-5. doi: 10.1021/jf035020+.
The alpha zein, the maize storage prolamin, is a mixture of several homologous polypeptides that shows two bands in SDS-PAGE, called Z19 and Z22. The conformation studies carried out by several authors in this mixture are conflicting. To elucidate these inconsistencies, we analyzed the conformation of the Z19 fraction, extracted from BR451 maize variety by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and small-angle X-ray scattering. The infrared results show that Z19 has 46% of alpha helix and 22% of beta sheet. The fast N-H to N-D exchange measured by (1)H NMR spectroscopy showed that Z19 is not a compact structure. The scattering measurements indicated an extended structure with 12 by 130 A. With these data, we have modeled the Z19 structure as a hairpin, composed of helical, sheet, turns, and secondary structures, folded back on itself.
α-玉米醇溶蛋白是玉米的贮藏醇溶蛋白，是几种同源多肽的混合物，在SDS-PAGE中显示两条带，称为Z19和Z22。几位作者对该混合物进行的构象研究结果相互矛盾。为了阐明这些不一致之处，我们通过傅里叶变换红外光谱、核磁共振和小角X射线散射分析了从BR451玉米品种中提取的Z19组分的构象。红外结果表明，Z19含有46%的α螺旋和22%的β折叠。通过（1）H NMR光谱测量的快速N-H到N-D交换表明，Z19不是紧密结构。散射测量表明其为12×130 Å的伸展结构。根据这些数据，我们将Z19结构模拟为一个发夹结构，由螺旋、折叠、转角和二级结构组成，自身折叠。
