Tryptophan-N-glucoside in Fruits and Fruit Juices

Abstract

In extracts prepared from various fruits as well as in fruit juices a single tryptophan glycoconjugate was detected by HPLC-MS analysis. Product ion spectra demonstrated the N-glycosidic linkage of a hexose moiety to the indole nitrogen. For structure elucidation, the novel tryptophan glycoside was isolated from pear juice and identified as N(1)-(beta-D-glucopyranosyl-(4)C(1))-L-tryptophan by (1)H, HH-COSY and (13)C NMR spectroscopy. Finally, we disclosed the biosynthetic origin of the novel tryptophan metabolite by demonstrating the enzymatic glycosylation of deuterium-labeled tryptophan, which was applied to pear fruit.

High-performance liquid chromatography with fluorescence detection for quantitation of tryptophan and tyrosine in a shrimp waste protein concentrate

“…This pattern was also shown for dried samples. These differences may be attributable to the fact that the tryptophan is a limiting factor in protein [37] or that the tryptophan content can be reduced in the protein hydrolysates [38]. Furthermore, the free tyrosine and tryptophan mean contents were, respectively, approximately 67% and 74% of their values in the total tyrosine and tryptophan for both protein concentrates.…”

Two new tryptophan derivatives from the seed kernels of Entada rheedei: Effects on cell viability and HIV infectivity

“…The 1 H and 13 C NMR chemical shifts (Table 1) of compounds 2 and 1 were almost superimposable. The 1 H NMR spectrum of 2 exhibited signals at δ 7.87 (brd, J = 8.2 Hz, H-7′); 7.16 (ddd, J = 1.3, 7.2, 8.2 Hz, H-6′); 7.08 (ddd, J = 1.2, 7.2, 7.9 Hz, H-5′), 7.67 (brd, J = 7.9 Hz, H-4′) amd 7.46 (brs, H-2′), characteristic of tryptophan derivatives [24,26,27]. The 13 C NMR spectrum showed a downfield shift of C-2 in compound 2 with respect to compound 1 (73.8 ppm in 2 vs 56.2 ppm in 1 ), suggesting the presence of an OH group at C-2 in compound 2 instead of the NH 2 group present in 1 .…”

Phosphorylation and Glycosylation of Bovine Lens MP20

“…It is possible that the glycosylation of MP20 involves an Nlinkage to the indole, as has been observed to occur through an enzymatic pathway in fruit. 35 A consensus sequence has been proposed, but proteins containing C-mannosylation show variability in this sequence, suggesting that more than one Cmannosyltransferase may be present or that other local features of the protein may be involved. 30 The in vivo function of C-mannosylation is not yet known, but site-directed mutagenesis of tryptophan residues that are C-mannosylated results in a loss of protein trafficking from the endoplasmic reticulum.…”