Find research datasets worth reusing

Fig. 22 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 22. Diverse products of allyl glucosinolate (GSL) depending on presence or absence of specifier proteins. The asterisks over the GSL, the isothiocyanate and the thiocyanate summarize the results of labeling studies (Benn, 1977; Rossiter et al., 2007) as previously detailed (Agerbirk and Olsen, 2012). All GSLs can form isothiocyanates, although some may be unstable, and nitriles. Only aliphatic GSLs with a terminal unsaturation can form epithionitriles. Only allyl GSL and two other GSLs (formally able to form a resonance-stabilized cation) can form organic thiocyanates. Some specifier proteins have other activities than those they are named from, as indicated in brackets. MYR, myrosinase; ESP, epithiospecifier protein; NSP, nitrile specifier protein; TFP, thiocyanate-forming protein.

Fig. 23 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 23. Participation of glutathione and a glutathione-S-transferase in forming a GSL-derived amine as a product of glucosinolate metabolism in intact cells, important for plant immunity. Question marks above some arrows signify steps that are demonstrated in vivo but for which specific enzymes are not yet known. Reactions are unbalanced. Amine and acid products are illustrated as the corresponding ammonium and carboxylate ions, as they would mainly exist at physiological pH. MYR, myrosinase.

Fig. 21 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 21. Selected examples of glucosinolate analogs synthesized for studying the interaction of natural glucosinolates with myrosinase.

Fig. 20 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 20. Synthesis of a glucosinolate epitope coupled to bovine serum albumin (BSA), intended for elicitation of an immune response.

Fig. 17 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 17. Two novel glucosinolates demonstrated by NMR and MS, but without conclusion of a single structure since the position of the methyl group is undetermined in each case.

Fig. 29 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 29. Possible sites for formation of isomers of the constant part of glucosinolates. Very high numbers of isomers of glucosinolates suggested in two recent publications could potentially be such "isoglucosinolates".

Fig. 16 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 16. Definition of the term selenoglucosinolate, precursor of an isoselenocyanate, according to the discoverers, Bertelsen et al. (1988).

Fig. 14 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 14. The usefulness of the J-resolved (JRES) spectrum for resolving overlapping signals. (A) The upfield part of the 1 H NMR spectrum of d40R in D O 2 and dioxane as internal standard (i.s.). A minor impurity (imp.) of MeOH from the HPLC isolation is seen. (B) In the JRES 1 H NMR spectrum, the splitting of signals is plotted (almost) perpendicular to the chemical shift x-axis, allowing resolution of signals at nearly identical chemical shift. The known coupling constants of the 6′a double doublet signal can be used for estimating coupling constants in the newly revealed signals. Three obvious triplets with coupling constant (J) of ca. 8 Hz can be seen. In addition, the complex multiplet of the 5′ proton is visible as a line of low intensity signals. Singlets from the i. s. and imp. do not show coupling, and all signals are seen at the same chemical shift coordinate as in the 1D spectrum. Unpublished results from identification of 40R (Agerbirk et al., 2001a).

Fig. 12 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 12. Complex coupling within branched aliphatic side chains in desulfoglucosinolates (dGSLs), and simplifying effect of substitution. (A) Side chain region of the 1 H NMR spectrum of 3-methylpentyl dGSL (d58) in D O 2 (Agerbirk et al., 2008, 2010a; Olsen et al., 2016). (B) Corresponding region of the spectrum of a hydroxyl derivative, 2-hydroxy-3-methylpentyl dGSL (d149) in D2O (Olsen et al., 2016). It is evident that the coupling of the 1a and 1b signals in B is now first order, and that the signals of the position 2 protons have disappeared from the illustrated range of chemical shifts (to be found at 3.95ppm). Occasional minor impurity peaks (imp) are generally recognizable by having peak areas less than unity.

Fig. 10 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 10. Logical sub-divisions in the group of "aromatic glucosinolates", defined as glucosinolates containing one or more aromatic moieties.

Fig. 2 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 2. Definition of the parent glucosinolate ion (A), and its use in naming natural derivatives (B, D), with numbering system indicated, using the originally proposed writing of names in one word (Dateo, 1961). The numbering system is retained in the isothiocyanate product (C). The modern practice by many authors of splitting glucosinolate anion names in two (given below each name) is followed in the rest of the text. Both practices are considered generally accepted.

Fig. 3 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 3. Examples of glucosinolates derived directly from a standard amino acid precursor, and meaning of the abbreviation 'GSL' in condensed structures.

Fig. 7 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 7. Biosynthesis of the rare, unusual glucosinolate (GSL) 3-methoxycarbonylpropyl GSL (Kjaer and Gmelin, 1957a) as evidenced by traditional tracer studies in an Erysimum sp. (Chisholm, 1973). Positions of radiolabeling are indicated with asterisks. Apart for the terminal methyl group derived from Met, the GSL was biosynthesized from homoGlu (probably derived from Glu), making it the only documented GSL biosynthesis from Glu. A more recent paper (Radulović et al., 2011) reported the free carboxylic acid, 3-carboxypropyl isothiocyanate from autolyzed Erysimum diffusum Ehrh. (diffuse wallflower), further supporting GSL biosynthesis from homoGlu in Erysimum spp. The brackets indicate the lack of modern spectroscopic confirmation of this structure, which is, however, based on very solid classical work.

Fig. 1. A in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 1. A simple glucosinolate (GSL) and its enzymatic conversion to an isothiocyanate (ITC). (A) Structure of benzyl GSL and hydrolysis to the aglucone. (B) Spontaneous rearrangement of the aglucone to benzyl ITC. (C) Configuration of the thiohydroximate double bond and some common terms used in discussing GSL structures. (D) The relation of a thiohydroximate ion to thiohydroxamic and –imic acids.

Fig. 5 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 5. Secondary modifications in glucosinolate (GSL) biosynthesis. (A) Biosynthesis of secondary modifications in Trp-derived GSLs ("indole GSLs") in Arabidopsis thaliana (Pfalz et al. 2011, 2016). (B) Biosynthesis of a more complex indole GSL is still unknown. (C) Two possible biosyntheses of p-hydroxybenzyl GSL (23), the relative importance of which in nature is not known. In the current paper, bold and square brackets around GSL numbers indicate incomplete MS and NMRdocumentation for their existence (Section 2).

Fig. 4 in Glucosinolate structural diversity, identification, chemical synthesis and metabolism in plants

Fig. 4. Biosynthesis of benzyl glucosinolate from Phe (Wittstock and Halkier, 2000; Wittstock and Halkier, 2002; Mikkelsen et al., 2002). An oxime is the first intermediate, followed by a complex transformation to the thiohydroximate, and finally glucosylation and sulfation. By introduction of the sulfate group in the final step, the unstable intermediate that leads to isothiocyanate formation (Fig. 1) is avoided. The donor of the thioglucose S is glutathione (Schläppi et al., 2008; Geu-Flores et al., 2009a). The relevant (E)-oxime is the immediate product of the CYP79 (Clausen et al., 2015). In the further core biosynthesis not shown, the identity of one intermediate is yet uncertain (either an aci-nitro or a nitrile oxide functionality) (Sønderby et al., 2010a).

publicMar 2022View details →

Data from: Context-dependent effects of shifting large herbivore assemblages on plant structure and diversity

Open the record for dataset details and reuse information.

publicJun 2013View details →

Data from: Rapid buildup of genetic diversity in founder populations of the gynodioecious plant species Origanum vulgare after semi-natural grassland restoration

Open the record for dataset details and reuse information.

publicAug 2019View details →

Data from: Functional diversity is a passenger but not driver of drought-related plant diversity losses in annual grasslands

Open the record for dataset details and reuse information.