Summary. An oviposition-deterring pheromone (ODP) of the European cherry fruit fly Rhagoletis cerasi L. was isolated from faeces using cellulose and several reverse phase TLC and HPLC procedures. The biological activity was evaluated by means of behavior tests and by electrophysiological recordings from tarsal contact chemoreceptors. The compound was structurally characterized as a N[15(fl-glucopyranosyl)oxy-8-hydroxypalmitoyl]-taurine by spectroscopic means. The configurations of C-8 and C-15 of the fatty acid constituent remain to be established by synthetic work.

Natural human insulin-like growth factor (IGF) I is a relatively large single chain peptide (mol. wt 7649) with a known sequence of 70 amino acids. C6----C48, C47----C52 and C18----C61 assignments have been previously proposed for the three disulphide bonds linking six cysteine residues (C6, C18, C47, C48, C52 and C61), on the basis of analogy (and homology) with proinsulin. In this work, IGF I synthesized by recombinant DNA technology (r-IGF I, with identical biological activity and chromatographic behaviour) was subjected to a three-step mass spectrometric analysis in combination with degradation methods for structural verification. Firstly, the correct molecular weight of the intact peptide was determined by high-mass fast atom bombardment (FAB) analysis. Secondly, twofold enzymatic degradation (chymotrypsin followed by V8 protease, 'FAB mapping' of the cleavage products) was employed in order that fragments with 'isolated' S-S bonds would be produced which allow an unambiguous assignment. This immediately established the C18----C61 linkage as it was contained in a singly bridged two-chain peptide. The two other S-S bonds, which cross-link C6 and the 'tight' C47 to C52 segment, remained 'unresolved' within a more complex, doubly bridged triple-chain peptide. Thirdly, further degradation of this structural block, in which cleavage of the C47-C48 bond was required to discern these bonds, was carried out by using FAB tandem mass spectrometry and (for additional corroboration) manual Edman degradation. Both procedures confirmed the original C6----C48/C47----C52 prediction.(ABSTRACT TRUNCATED AT 250 WORDS)

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The conversion of dihydroneopterin triphosphate in the presence of 6-pyruvoyl tetrahydropterin synthase was followed by 'H-NMR spectroscopy. The interpretation of the spectra of the product is unequivocal: they show formation of a tetrahydropterin system carrying a stereospecifically oriented substituent at the asymmetric C(6) atom. The spectra are compatible with formation of a (3')-CH3 function, and with complete removal of the 1' and 2' hydrogens of dihydroneopterin triphosphate. The fast-atom-bombardment/mass spectrometry study of the same product yields a [M+H]+ ion at m/z 238 compatible with the structure of 6-pyruvoyl tetrahydropterin. The data support the proposed structure of 6-pyruvoyl tetrahydropterin as a key intermediate in the biosynthesis of tetrah ydrobiopterin.The biosynthetic pathway of tetrahydrobiopterin (BH,) has been elucidated in its prominent features in the past few years by the convergent efforts of several groups [I -91. The following sequence is now being widely accepted: GTP 4 7,X-dihydroneopterin triphosphate (NH2TP) + h-pyruvoyl-5,6,7,%tetrahydropterin (PPH,) 6-lactoyl-5,6,7,8-tetrahydropterin or 6-hydroxy-acetonoyl-5,6,7,X-tetrahydropterin + tetrahydrobiopterin (BH,).The enzymes involved have also been purified and characterized 14, 10-281. While the chemical structures and some of the properties of these intermediates are known, the mechanisms by which 7,s-dihydroneopterin triphosphate (NH2TP) and 6-pyruvoyl-5,6,7,8-tetrahydropterin (PPH4) are formed have not yet been elucidated. The first step, the conversion of GTP to NH2TP, is an apparently rather complicated process catalyzed by a single enzyme, GTP cyclohydrolase I, and involving ring opening of GTP, extrusion of a formyl equivalent, rearrangement of the ribosyl moiety and reclosure to form a six-membered ring [19, 201. The second step also involves two chemically distinct processes, the elimination of triphosphate from the terminal (C3') position of the C(6) side chain (23, 21 -231, and an internal, Amadori-type rearrangement during which the N(5)-C(6) double bond of NH2TP is reduced at the expense of oxidation of C(l')-OH to C(l')=O 13, 12,21,[23][24][25][26] A further major issue at the onset of our work was the chemical identity of PPH, and its properties. The intermediacy of this molecule in BH, biosynthesis had been proposed by several groups 16, 7, 23 -251, but its high instability and the difficulties in obtaining substantial quantities of material have hindered structural studies. In fact, the only feasible procedure for its preparation requires purified 6-pyruvoyl tetrahydropterin synthase and purified NH2TP [27], the latter also having to be prepared enzymatically from GTP [28]. Furthermore, the evidence presented for its structure was deduced from trapping experiments involving modifications of the pyruvoyl function such as reduction with NaBH4 or enzymatically with NADPH to BH4 [3, 4, 6, 8, 22, 23, 25, 26, 291. In the present work we report detailed 'H-NMR and fastatom-bombardment/mass spectrometry (FAB/MS) ...