Insecticidal Components from Field Pea Extracts: Sequences of Some Variants of Pea Albumin 1b

详细信息    查看全文

• 作者：Wesley G. Taylor ; Daniel H. Sutherland ; Douglas J. H. Olson ; Andrew R. S. Ross ; and Paul G. Fields
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2004
• 出版时间：December 15, 2004
• 年：2004
• 卷：52
• 期：25
• 页码：7499 - 7506
• 全文大小：85K
• 年卷期：v.52,no.25(December 15, 2004)
• ISSN：1520-5118

文摘

Methanol soluble insecticidal peptides with masses of 3752, 3757, and 3805 Da, isolated from crudeextracts (C8 extracts) derived from the protein-enriched flour of commercial field peas [Pisum sativum(L.)], were purified by reversed phase chromatography and, after reduction and alkylation, weresequenced by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometrywith the aid of various peptidases. These major peptides were variants of pea albumin 1b (PA1b)with methionine sulfoxide rather than methionine at position 12. Peptide 3752 showed additionalvariations at positions 29 (valine for isoleucine) and 34 (histidine for asparagine). A minor, 37 aminoacid peptide with a molecular mass of 3788 Da was also sequenced and differed from a knownPA1b variant at positions 1, 25, and 31. Sequence variants of PA1b with their molecular masseswere compiled, and variants that matched the accurate masses of the experimental peptides wereused to narrow the search. MALDI postsource decay experiments on pronase fragments helped toconfirm the sequences. Whole and dehulled field peas gave insecticidal C8 extracts in the laboratorythat were enriched in peptides with masses of 3736, 3741, and 3789 Da, as determined by high-performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry. It wastherefore concluded that oxidation of the methionine residues to methionine sulfoxide occurred primarilyduring the processing of dehulled peas in a mill.Keywords: Pisum sativum; pea albumins; sequence variants; mass spectrometry; oxidation; methionine; methionine sulfoxide