Study by liquid secondary ion and electrospray mass spectrometry of synthesized and formed-in-source metallocorroles

Liquid secondary ion and electrospray mass spectrometry were used to study the complexation in-source of 5,10,15-tris(pentafluorophenyl)corrole with several divalent transition-metal ions. The metallocorrole ions formed in-source were identified by comparing their product ion mass spectra with the spectra of the same ions formed from metallocorroles obtained from classical procedures. Positive metallocorrole ion formation is accompanied by oxidation of the metal centre. Mechanisms were proposed for the oxidation processes, and data from negative-ion spectra reinforced these mechanisms.     

痕量完整天然寡糖链的液态二次离子质谱测定

痕量、未衍生、完整的天然寡糖可用质谱法直接获得重要的结构信息。用负离子LSIMS测出了n mol级IgM中的高甘露糖型和杂交型糖链分子量及序列。对麦芽七糖、异麦芽七糖、古洛糖醛酸十聚体及若干天然寡糖谱图中碎片离子进行了研究,从糖链混合物的质谱图中也能分析出有用的分子结构。     

Structure of lipid A from the marine gram-negative bacterium <Emphasis Type="Italic">Pseudoalteromonas nigrifaciens</Emphasis> IAM 13010<Superscript>T</Superscript>

The structure of lipid A from the marine γ-proteobacterium Pseudoalteromonas nigrifaciens IAM 13010^T that was prepared by hydrolysis of the corresponding lipopolysaccharide by acetic acid (1%) was determined by chemical analysis, ¹³C NMR spectroscopy, and MALDI/TOF and LSIMS mass spectrometry. It was shown that lipid A is a β-1,6-bonded disaccharide of glucosamine that is substituted by two phosphoric acids (in the C1 and C4′ positions), two (R)-3-hydroxyalkanoic (normal and branched) acids with ester bonding (at the C3 and C3′-positions), and (R)-3-hydroxydodecanoic and (R)-3-dodecanoyloxydodecanoic acids (both with amide bonding at C2′ and C2, respectively). It was hypothesized that this type of structure is typical of lipid A from bacteria of the genus Pseudoalteromonas in general. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 425–429, September–October, 2007.