The genotyping of the various isoforms of Apolipoprotein E (apo E) has been performed using matrix-assisted laser desorption/ionization (MALDI-MS). The polymerase chain reaction was used to amplify the specific apo E gene sequence followed by digestion with Cfo I ( Clostridium formicoaceticum ), for generating restriction fragments for rapid and accurate mass analysis. An exonuclease I digestion step was introduced to remove the unused primers after PCR, which can otherwise interfere in the mass spectral analysis. By replacing the gel electrophoresis detection step with MALDI-MS, restriction isotyping of the apo E gene was achieved. Genotyping of an unknown sample obtained from an independent diagnostic laboratory demonstrated the validity of the MALDI-MS method for the routine clinical analysis of apo E. © 1998 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35073/1/281_ftp.pd

Akel, Nahida

Kachman, Maureen T.

Killeen, Anthony A.

Lubman, David M.

Siemieniak, David R.

Srinivasan, Jannavi R.

Rapid Communications in Mass Spectrometry

A semi‐preparative (high‐performance liquid chromatography) method for separation of cyclosporin metabolites in a fungal fermentation sample was developed. By using the optimized chromatographic separation, 20 cyclosporin metabolites in a process sample were isolated, and their molecular masses measured by double focusing sector mass spectrometry. The structures of some of the cyclosporin congeners were investigated by tandem sector mass spectrometry using fast atom bombardment ionization. The isobaric cyclosporins D ([Val2]CS) and G ([Nva2]CS) were differentiated by significantly different relative intensities of a fragment ion at m/z 30 [CH4N]+ from a precursor ion at m/z 72 [C4H10N]+. Otherwise the tandem mass spectrometry (MS/MS) spectra of the fragment ions of the two isomers are very similar. Cyclosporin A and iso‐cyclosporin A were also analysed by high energy MS/MS. No significant fragment ions were found to provide distinctions between them. Relatively good overviews of process samples containing very similar structures were achieved by combining LC separation, molecular ion recognition and MS/MS characterization

Tuominen, Jari

Suortti, Tapani

Ishikawa, K.

Lundell, J.

Koga, Y.

VTT Research System

Separation of cyclosporins by high-performance liquid chromatography and mass spectrometric study of cyclosporin metabolites

Using the condensation of N-protected amino acids with 2,6-bishydroxylmethyl pyridine, we synthesized six di-esters and four mono-esters. All ten esters are new compounds. They are all important intermediate compounds for synthesis of macrocylic compounds containing amino acid and pyridyl units. Because there are several complex sites in these macrocycles, they may be useful as enzyme models or as templates in asymmetric resolution. This paper reports fast-atom bombardment (FAB) mass spectrometry of these two kinds of esterification products, and electron impact (EI) of four mono-esters. Their FAB mass spectrometric behavior was studied with the aid of both mass-analyzed ion kinetic energy spectrometry and high-resolution data. The EI fragmentation mechanisms of the mono-esters are also studied with the aid of mass-analyzed ion kinetic energy spectrometry and high-resolution data. We discovered that, under FAB conditions, each mono-ester yields (2M+H](+) ions, and the ionizing proton is connected with the nitrogen atom in the pyridine ring. Through the high-resolution analysis of compound 10 under EI, we found two kinds of ions at m/z 139. One is a 2,6-bishydroxylmethyl pyridine residue, which is more stable than the other residue formed by the loss of one oxygen atom from p-toluenesulfonyl ion. Also of importance is the fact that a H-atom rearrangement proceeds via a four-membered ring intermediate under both FAB and EI conditions. (C) 1998 John Wiley &amp; Sons, Ltd.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000075351000004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, AnalyticalSpectroscopySCI(E)1ARTICLE161057-10621

Chen, YT

Hua, WT

He, MY

He, XR

Xing, QY

Institutional Repository of Peking University

Study of mass spectra of the esterification products synthesized from   N-protected amino acids and 2,6-bishydroxylmethyl pyridine

The mass spectrometric behaviour of seven tetrasubstituted 3a,4,5,11-tetrahydro-3H-1,2,4-triazolo[4,3d][1,5]benzothiazepines has been studied with the aid of mass-analysed ion kinetic energy spectrometry and exact mass measurements under electron impact ionization, All compounds show a tendency to eliminate a neutral substituted or unsubstituted styrene molecule from the thiazepine ring to yield 1,2,4-triazolo[4,3b][1,3]benzothiazole ions, and further undergo reverse 1,3-dipolar cycloadditions to give benzothiazole ions. The Formation of stable conjugated fused tetracyclic systems, substituted 1,2,4-triazolo[4,3-f]phenanthridine ions, under electron impact ionization, has also been found. (C) 1998 John Wiley &amp; Sons, Ltd.Chemistry, AnalyticalSpectroscopySCI(E)17ARTICLE161115-11171

Xu, JX

Jin, S

Mass spectrometric studies of tetrasubstituted   3a,4,5,11-tetrahydro-3H-1,2,4-triazolo[4,3-d][1,5]benzothiazepines

The chemical purity of two synthetic 4‐boronophenylalanine (BPA, C9H12O4BN) batches produced by two different pathways were investigated by high performance liquid chromatography/electrospray mass spectrometry. Currently, BPA is one of the most important clinical boron carriers in boron neutron capture therapy (BNCT). Low energy tandem mass spectrometry was used to elucidate the structure of BPA and two minor signals eluting later than the major compound. In the mass spectrom a very intense singly charged [M+H]+ ion m/z 209 was observed. The ratio of 10B/11B was estimated also. The product‐ion spectrum of BPA shows distinct losses of 18, 46 and 89 u. Based on the fragmentation of the major compound two impurities were characterized. In both cases an intense molecular ion, 244 u and 285 u was observed. Knowing the synthetic pathway and fragmentation of the major compound we suggest the following formulae for the impurities: C9H10O2BrN and C15H16O4BN. Further evidence to the first impurity is the detected isotope pattern, corresponding to bromine. The existence of the impurities can be explained and avoided by exploring the synthetic pathways used. High performance liquid chromatography/electrospray mass spectrometry was demonstrated to be an important novel analytical instrument to check the purity of BPA prior to clinical studies in BNCT

Vähätalo, Jyrki

Kokkonen, Juha

Kříž, Otomar

Karonen, Sirkka-Liisa

Kallio, Merja

Trace impurities identified by HPLC/Electrospray MS in two different synthetic batches of 4-boronophenylalanine

William Griffiths

Cronfa at Swansea University

Analysis of variant forms of porcine surfactant polypeptide-C by nano-electrospray mass spectrometry

Deep Blue Documents