scholarly journals The conversion of 4-hydroxypyrazolo-[3,4-d]pyrimidine (allopurinol) into 4,6-dihydroxypyrazolo[3,4-d]pyrimidine (oxipurinol) in vivo in the absence of xanthine–oxygen oxidoreductase

1969 ◽  
Vol 112 (4) ◽  
pp. 527-532 ◽  
Author(s):  
R. A. Chalmers ◽  
R. Parker ◽  
H A Simmonds ◽  
W. Snedden ◽  
R. W. E. Watts
Keyword(s):  
Mass Spectrometry ◽  
Xanthine Oxidase ◽  
Infrared Spectra ◽  
Metabolic Pathway ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
Spectrometric Investigation ◽  
Mass Spectrometric Investigation ◽  
Congenital Deficiency

1. A patient with congenital deficiency of xanthine oxidase (EC 1.2.3.2) (xanthinuria) excreted the xanthine isomer 4,6-dihydroxypyrazolo[3,4-d]pyrimidine (oxipurinol) in his urine when the hypoxanthine isomer 4-hydroxypyrazolo[3,4-d]pyrimidine (allopurinol) was given by mouth. 2. The identity of the oxipurinol that the patient excreted was established by mass spectrometry. 3. The mass spectra and infrared spectra of allopurinol, oxipurinol, hypoxanthine and xanthine are compared. 4. A mechanism for the fragmentation of these compounds that occurs during their mass-spectrometric investigation is proposed. 5. A possible metabolic pathway for the oxidation of allopurinol to oxipurinol in the absence of xanthine oxidase is discussed.

Photochemical Studies by Means of a Field Ion Mass Spectrometer

1966 ◽  
Vol 21 (1-2) ◽  
pp. 135-140 ◽  
Author(s):  
H. Okabe ◽  
H. D. Beckey ◽  
W. Groth
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Flow System ◽  
Low Pressure ◽  
Ion Source ◽  
Mass Spectrometric ◽  
Gas Pressure ◽  
Spectrometric Investigation ◽  
Mercury Lamp ◽  
Mass Spectrometric Investigation

A mass spectrometric investigation was carried out on the direct photolyses of propene, 1-butene, and hydrazine at 1849 A with a field ion source in a flow system. Comparisons were made with Pt tip and wire emitters. It was found that, without illumination, mass spectra obtained with the wire were accompanied by a number of fragment peaks amounting to almost 1%. Since these peaks interfere with those produced photochemically, the tip emitter was used mostly for the photochemical studies although it gave 100 times less current and was less stable. The photochemical products formed at a gas pressure of 10 μ by a low pressure mercury lamp were detected after approximately 10 m sec. The three main peaks observed in the propene photolysis were at masses 27, 28, and 56, indicating the processes:C3H6+hv→C2H3+CH3, C3H6+hv→C2H4+CH2, CH2+C3H6→C4H8.The photolysis of 1-butene gave four main peaks at masses 40, 41, 42, and 70, suggesting steps, C4H8+hv→C3H4+ (H+CH3) or CH4, C4H8+hv→C3H5+CH3, C4H8+hv→C3H6+CH2, CH2+C4H8C5H10.The only peak found with the photolysis of hydrazine was at mass 17, indicating the step, N2H4+hv→NH3+NH.The possibility of forming these products by secondary processes is discussed.

scholarly journals A mass-spectrometric investigation of the mechanism of the semisynthetic transformation of pig insulin into an ester of insulin of human sequence

1984 ◽  
Vol 220 (1) ◽  
pp. 189-196 ◽  
Author(s):  
K Rose ◽  
J Gladstone ◽  
R E Offord
Keyword(s):  
Mass Spectrometry ◽  
New York ◽  
Oxygen Isotope ◽  
Carbonyl Group ◽  
Mass Spectrometric ◽  
Spectrometric Investigation ◽  
Mass Spectrometric Investigation ◽  
Alanine Residue ◽  
Human Sequence ◽  
Ester Product

In the trypsin-mediated semisynthetic transformation of pig insulin into an ester of insulin of human sequence, the B30 alanine residue of the pig hormone is replaced by an ester of threonine. The mechanism of this reaction was investigated by carrying out the transformation in a medium containing water enriched with 18O. Subsequent analysis by combined g.l.c.-mass spectrometry demonstrated that the oxygen isotope, is incorporated into the B29 carbonyl group of the insulin ester product. This result, together with those of appropriate controls, supports the conclusion that the transformation occurs, in the system studied, by a mechanism involving hydrolysis followed by coupling, and not by direct transpeptidation as has been previously found the case for another such system [Markussen & Schaumberg (1983) in Peptides 1982 (Bláha & Malon, eds.), pp. 387-394, W. de Gruyter, Berlin and New York].

ChemInform Abstract: Mass-Spectrometric Investigation of Ring-Chain Tautomers of 3-Amino(hydroxy)pyrazolidines.

ChemInform ◽  
1987 ◽  
Vol 18 (18) ◽  
Author(s):  
A. G. KALADARISHVILI ◽  
P. B. TERENT'EV ◽  
S. V. AFANAS'EVA ◽  
L. A. SVIRIDOVA ◽  
R. R. RAZAKOV ◽  
...  
Keyword(s):  
Mass Spectrometric ◽  
Spectrometric Investigation ◽  
Mass Spectrometric Investigation

Mass spectrometric investigation of the ionic polymerization in gaseous ethylenimine

1970 ◽  
Vol 66 ◽  
pp. 1464 ◽  
Author(s):  
A. Giardini-Guidoni ◽  
A. Mele ◽  
F. Vecchio Cattivi ◽  
F. Zocchi
Keyword(s):  
Mass Spectrometric ◽  
Spectrometric Investigation ◽  
Mass Spectrometric Investigation
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