Barley Grain Non-specific Lipid-Transfer Proteins (ns-LTPs) in Beer Production and Quality

Abstract

Plant non-specific lipid-transfer proteins (ns-LTPs) are known for their ability to transfer various lipids between membranes in vitro. These ubiquitous basic proteins, that all share alpha structure stabilized by four disulphide bridges, are characterized by the presence of a hydrophobic cavity able to accommodate lipid molecules. According to molecular mass, this multigene family is subdivided into two subfamilies, ns-LTP1 (9 kDa) and ns-LTP2 (7 kDa); both located in the aleurone layer of the cereal grain endosperm. Ns-LTP1 is a prominent protein in barley grain, malt and beer. Numerous studies performed on its structure and function confirm its important role in grain protection, as well as brewing technology. As the major beer protein crucial for many aspects of brewing, ns-LTP1 can affect beer production and quality. Comparatively, there is less data available on the less abundant ns-LTP2. In this review, the focus is on recent progress on the structure, biological and technological function of barley grain ns-LTP1 and ns-LTP2, with an emphasis on their importance in brewing.

Nonhost Resistance of Barley to Different Fungal Pathogens Is Associated with Largely Distinct, Quantitative Transcriptional Responses

“…Unigenes of these subsets associated with absolute DI values larger than 0.2 and 0.3 for Mag and PM interactions, respectively, are briefly discussed here. Four of the most prominently accumulating marker transcripts for the nonhost interaction with CD encode lipid transfer proteins, further supporting an important, defense-related role of this protein family in barley (Molina and Garcia-Olmedo, 1997) that is also impacting malt quality and plays a role as a major food allergen (Broekaert et al, 1997;Breiteneder and Mills, 2005;Stanislava, 2007). Among the genes with more strongly down-regulated transcript levels during CD interaction are four chloro- Table S2) is shown.…”

Long distance movement of DIR1 and investigation of the role of DIR1-like during systemic acquired resistance in Arabidopsis

“…DIR1 antibody signals of both ~7 and 15 kDa were detected in protein gel blot analysis of petiole exudates and IWFs collected from wild type plants suggesting that DIR1 is present in monomeric form and also exists as either a homodimer as is the case for the peach Prup3 LTP (Pasquato et al, 2005) or as a heterodimer with another LTP, as is the case for the barley LTP1-LTP2 complex (Gorjanović et al, 2005; Gorjanović, 2007). The LTP1-LTP2 dimer was disrupted in the presence of reducing agents suggesting that disulfide bonds hold the monomers together (Gorjanović, 2007).…”

“…The LTP1-LTP2 dimer was disrupted in the presence of reducing agents suggesting that disulfide bonds hold the monomers together (Gorjanović, 2007). Incubation of DIR1 exudates in elevated concentrations of a reducing agent (200 mM) resulted in the appearance of the ~7 kDa band.…”

Exploitation of Brewing Industry Wastes to Produce Functional Ingredients

“…The lipids in barley are located in the endosperm and embryo, as their role is to provide nutrients and energy for the new, germinating barley plant. Although the endosperm is almost completely solubilised in mashing, most of the lipids remain with spent grains and are not transferred to wort [54][55][56]. According to recent studies [5,8,55,57], the total lipid contents (TLs) of BSG [8,54].The predominant lipid classes identified in the total lipids of BSG were triacylglycerols (TAG) (55-67% total lipids), followed by free fatty acids (FFA) (18-30%), diacylglycerols (DAG) (7.7-5.7%), monoacylglycerols (MAG) (1.7%), phospholipids (PL) (9.1%) and steroid compounds (SC) (hydrocarbons, ketones, free sterols, sterol esters and sterol glycosides) (5%) [5,55].…”