Howard R. Morris

Fast atom bombardment: A new mass spectrometric method for peptide sequence analysis

Abstract We have studied a selection of peptides using a new mass spectrometric ionisation technique - fast atom bombardment (FAB). We define the fragmentation pathways observed and comment on the utility in sequence analysis. A simple acetylation experiment is shown to aid rapid sequence assignment.

FAB-MAPPING of recombinant-DNA protein products☆

A new method is described for screening and establishing the primary structure of proteins. The procedure is both rapid and sensitive and allows study of the C-terminus of the protein with equal facility to the N-terminus. This new strategy which is illustrated here for the polypeptide hormone Insulin, has obvious applications in recombinant DNA biotechnology research, in post-translational modification and site-directed mutagenesis studies, or any other aspect of modern protein chemistry requiring accurate definition of primary structure.

Fast-atom-bombardment mass-spectrometry for carbohydrate-structure determination

Abstract The potential of fast-atom-bombardment (f.a.b.) mass-spectrometry in the carbohydrate field was assessed with the aid of unmodified, permethylated, and peracetylated oligosaccharides and glycosphingolipids. F.a.b. spectra are presented for ( d -Gal→ d -GlcNAc) 5 →( d -Man) 3 → d -GlcNAc, permethylated ( d -Gal→ d -GlcNAc) 5 →( d -Man) 3 - d -[ 2 H]GlcNAcol, permethylated gangliotetraosylceramide, and reduced and peracetylated tetra- to hepta-saccharides from human milk. From unmodified oligosaccharides, pseudomolecular ions (M + Na + ) were obtained as major ions in the high-mass range. Permethylated oligosaccharides and glycosphingolipids gave pseudomolecular ions (M + H + ) of high intensity, together with fragment ions of high diagnostic importance. At ambient temperature, f.a.b. spectra could only be obtained for the lower homologs of per- O -acetylated oligosaccharides. Reduced and peracetylated penta- to hepta-saccharides from human milk gave f.a.b. spectra only after heating of the target.

The role of arachidonate lipoxygenase in the release of SRS-A from guinea-pig chopped lung.

The immunological release of SRS-A was investigated in guinea-pig chopped lung. A number of unsaturated fatty acids, all of which are substrates for arachidonate lipoxygenase were found to potentiate the release of SRS-A. This potentiation was enhanced by indomethacin, a cyclo-oxygenase inhibitor, and completely reversed by nordihydroguaiaretic acid (NDGA) and eicosatetraynoic acid (ETA) which inhibit lipoxygenase. This suggests that some aspect of arachidonate lipoxygenase action stimulates release of SRS-A and that release of SRS-A is increased by redirection of arachidonic acid (AA) metabolism via the lipoxygenase pathway (Hamberg, 1976). However, although exogenous 14C-AA increased SRS-A output it was not incorporated into SRS-A.

A rapid and specific method for the high resolution purification and characterization of neuropeptides.

Abstract: High resolution purification procedures for the separation and characterization of neuropeptides are described. The methods, which are complementary, are based on ion exchange chromatography and reverse phase high pressure liquid chromatography and are designed to be used in conjunction with radioimmunoassays and bioassays for known peptides or structural identification in the case of peptides of unknown sequence. The high pressure liquid chromatographic method is versatile, highly reproducible and applicable to picomolar quantities of peptides and it gives very high resolution between most of the neuropeptides of present‐day interest. The applicability of the method to the study of crude brain extracts is demonstrated.

Structure determination of carbohydrates and glycosphingolipids by fast atom bombardment mass spectrometry

Abstract We have used fast atom bombardment mass spectrometry to aid the structural analysis of blood group glycosphingolipids, carbohydrates excreted by gangliosidosis patients, glucans from fast growing Rhizobium species and a variety of plant cell wall oligosaccharides. Samples have been examined in their native form or as acetyl, permethyl, methoxime or pentafluorobenzyloxime derivatives. Negative FAB spectra of permethylated carbohydrates have been obtained for the first time by salt dosing. High sensitivity for permethylated samples has been achieved in the positive mode by ammonium cationisation. Spectra up to m/z 6620 are reported for permethylated glucans.

Platelet-activating factor stimulation of peptidoleukotriene release: inhibition by vasoactive polypeptide.

Leukotriene (LT) release stimulated by platelet activating factor was inhibited by vasoactive intestinal polypeptide (VIP) in an in vitro rat lung preparation. This was detected by HPLC and radioimmunoassay. LTC4, although the major species in the stimulatory model used, was not detected in peptide-treated preparations and LTD4 and LTE4 levels were considerably reduced.

Primary and secondary structure of antifreeze peptides from arctic and antartic zoarcid fishes

Antifreeze peptides were isolated from Rhigophila dearborni, an antarctic eel pout, and Lycodes polaris, an arctic eel pout (both from the family Zoarcidae). The primary structures of two peptides, one from each species, were determined using a combination of Edman degradation and mass spectrometric techniques. The two sequences show a high degree of homology with nearly 80% of the residues being identical. These peptides are also homologous to antifreeze peptides from a third eel pout which inhabits the north Atlantic Ocean. The CD spectra of all of these peptides are also very similar. Unlike the antifreeze peptides of cottid fishes, the structures of antifreeze peptides from zoarcid fishes appear to be highly conserved, despite the large geographic distances which separate the different species. The zoarcid peptides also appear to have structures very different from other fish antifreezes.

Glutamyl‐Taurine Is the Predominant Synaptic Taurine Peptide

Abstract: Several taurine‐containing peptides have been identified from trichloracetic acid extracts of synaptosomes and their subcellular vesicles prepared from calf brain. These peptides contain aspartic and glutamic acids, serine and taurine, and are often present in an N‐acetylated form. The peptides were isolated as single spots by TLC. Glutamyl‐taurine was found to be the predominant structure when analyzed by fast atom bombardment (FAB) mass spectrometry.

A mass spectrometric study of the structure of Sterol Carrier Protein SCP2 from ratliver

Abstract The amino acid sequence of Sterol Carrier Protein 2 (SCP 2 ) isolated from rat has been investigated. Using a novel mass spectrometric mapping approach, the C-terminus was found to be extended beyond the previously published sequence. Carbohydrate analysis of SCP 2 samples suggest the presence of tightly bound mannose oligosaccharide of 5–10 residues, although probably not in a glycoprotein linkage.