Characterization of a 19 kDa -Zein of High Purity

详细信息    查看全文

• 作者：Vanessa Cabra ; Roberto Arreguin ; Amanda Galvez ; Maricarmen Quirasco ; Rafael Vazquez-duhalt ; and Amelia Farres
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2005
• 出版时间：February 9, 2005
• 年：2005
• 卷：53
• 期：3
• 页码：725 - 729
• 全文大小：127K
• 年卷期：v.53,no.3(February 9, 2005)
• ISSN：1520-5118

文摘

A highly pure images/gifchars/alpha.gif" BORDER=0>-zein was extracted from corn flour using ethanol (95%). Subsequently, ion-exchangechromatography was performed, using SP-Sepharose that yielded a highly homogeneous protein.This protein migrated as a single band in 20% SDS-PAGE and in pH gradient gels, showing anisoelectric point of 6.8. Mass spectrometry (MALDI-TOF-MS) showed a single peak with a molecularmass of 24 535 Da. It was identified as Z19, when comparing the sequence obtained in an automaticEdman sequencer with the Swissprot database using BLAST. The molar extinction coefficient,determined by dry weight in 70% methanol, was 12 415.49 M^-1 cm^-1 at 280 nm. Light scatteringshowed its presence in a monodispersed state of 44-66 kDa aggregates in methanol (70%). Circulardichroism spectra allowed the estimation of an images/gifchars/alpha.gif" BORDER=0>-helix content that was lower than the one found fora mixture of two images/gifchars/alpha.gif" BORDER=0>-zeins but with a higher content of images/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> sheets.Keywords: Zein; protein characterization; Z19; MALDI-TOF-MS; circular dichroism