Negative ion fast atom bombardment-tandem mass spectrometry for structural analysis of isoprenoid diphosphates

Applicability of negative ion fast atom bombardment (FAB)-tandem mass spectrometry (MS/MS) was examined in trace mixture analyses and structural assignments of some isoprenoid diphosphates. Negative ion FAB-MS spectra using a glycerol matrix of these isoprenoid diphosphates showed predominantly molecular ions (M-H)- together with fragment ions at m/z 177 (H3P2O7)-, 176 (H2P2O7)-, 159 (HP2O6)-, and 79 (PO3)- which were characteristic of the diphosphate ester moiety. The molecular ions did not overlap with peaks arising from any impurities even when crude sample such as butanol extracts from enzymatic reaction mixtures were directly analyzed without any purification. Moreover, collisionally activated dissociation spectra of the molecular ion showed many structurally significant fragment ions which enabled us to elucidate the structures of such irregular alkyl chain moieties as those having a homoisoprenoid skeleton or substituted structures. These studies indicate that negative ion FAB-MS/MS is a simple and useful technique for trace mixture analysis and structure elucidation of isoprenoid diphosphates.     

Pulse sequences generated by a degenerate analog neuron model

The response characteristics of an electronic neuron model proposed by the authors are investigated. Periodic stimulating pulse sequences with a fixed frequency are applied to the analog neuron model and the response pulse sequences are studied. In the degenerate case, the state transition of the neuron model during one period of the stimulating pulse sequence is described by a first order piecewise linear difference equation with a jump. It is shown that the periodic response pulse sequences of the neuron model belong to a special class of pulse sequences generated by a simple algorithm, and that the relation between the pulse width (or amplitude) of the stimulating pulse and the firing rate of the neuron model takes the form of an extended Cantor function.     

Preparation of Uridine Diphosphate-N-Acetylgalactosamine from Uridine Diphosphate-N-Acetylglucosamine by Using Microbial Enzymes

A method was developed for the large scale preparation of uridine diphosphate-N-acetylgalactosamine (UDP-GalNAc) from uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) by means of microbial enzymes. With Bacillus subtilis cell-free extract as a source of UDP-GlcNAc 4-epimerase, about 35% of the UDP-GlcNAc added was converted to UDP-GalNAc. After the residual UDP-GlcNAc was degraded to uridine triphosphate and N-acetylglucosamine-1-phosphate with a protamine-treated extract of bakers' yeast as a source of UDP-GlcNAc pyrophosphorylase, UDP-GalNAc was separated by anion-exchange column chromatography. The nucleotide was recovered by adsorption on charcoal and elution with ammoniacal ethanol. The final yield was about 100 μmol.     

Degradation of Xyloglucan by Wall-bound Enzymes from Soybean Tissue I. Occurrence of Xyloglucan-degrading Enzymes in Soybean Cell Wall

An enzyme preparation that catalyzes the degradation of xyloglucanwas obtained by extraction of the cell walls of soybean hypocotylswith a buffer containing 1.0 M NaCl. The enzyme preparationwas shown to catalyze two-step degradation of xyloglucan. Thepolysaccharide was first degraded into comparatively large fragments,which were then further degraded into monosaccharides. In orderto elucidate the mode of degradation of the xyloglucan duringcell growth, the activities of xyloglucandegrading enzymes ofsoybean-hypocotyl segments were assayed at different stagesof elongation. The total activities of the degrading enzymeswere lower in the elongating regions than in the non-elongatingregions. However, high levels of endo-ß-l,4-glucanasewere found in the elongating regions. These results suggestthat xyloglucan is hydrolyzed by endo-ß-1,4-glucanaseinto comparatively large fragments at the initial stage of growthand the resulting fragments are further degraded into monosaccharidesduring cell elongation. (Received May 20, 1981; Accepted August 8, 1981)     

Interaction between Sendai virus and KB cell lines with altered cell fusion ability: a study employing electron spin resonance.

The nature of the interaction between Sendai virus and Sil mutant cells was examined by measuring a change in ESR spectrum of spin-labeled phosphatidylcholine molecules on the viral envelope. When spin-labeled virus was incubated with the Sil cells that had a reduced ability to respond to virus-induced cell fusion, interchange of the phospholipid molecules between viral envelope and cell surface membrane occurred to a smaller extent than that observed with parental cells. Moreover, the degree of the interchanging correlated with the degree of the fusion capacity of the mutant lines. The results show that the mutant cells carry such a lesion(s) on their surface membranes that the viral envelopes can hardly fuse into them.     

Studies in the Cyperaceae of Thailand I. New and otherwise noteworthy species of Fimbristylis

Six Thai species ofFimbristylis, including two new ones, are taxonomically discussed, and some range extensions into Burma are reported. Described as new areFimbristylis kernii from the neighborhood ofF. hookeriana, andF. smitinandii, a clearcut species of the sectionAbildgaardia.     

Effect of the pH of culture medium on the alkalophilicity of a species of Bacillus

The amino acid incorporation and -aminoisobutyric acid (AIB) uptake of an alkalophilic Bacillus grown at pH 8.2 (the pH 8-bacteria) were much less pH dependent (less alkalophilic) than those of the organisms grown at pH 10.0 (the pH 10-bacteria), respectively. The rate of AIB uptake of the pH 10-bacteria was almost the same as that of the pH 8-bacteria, while the rate of amino acid incorporation of the pH 10-bacteria was higher than that of the pH 8-bacteria in alkaline environments. The colloidal titration with clupein showed that the amount of negative charge on the pH 10-bacteria was greater than that of the pH 8-bacteria in alkaline environments. Considerable difference in protein composition was observed between the membranes of the pH 8-and 10-bacteria, while no difference was observed in phospholipid composition.Abbreviations AIB Amino-isobutyric acid     

Effect of light on nonphotosynthetic microorganisms. II. Photochromogenicity in genus Streptomyces.

The effect of light on the pigmentation of various strains belonging to the genus Streptomyces was investigated. It was revealed that six species of streptomycetes, S. massaporeus, S. phaeopurpureus, S. chibaensis, S. salmonicida, S. fluvissimus and S. longispororuber, were photochromogenic, i.e., these strains can be photoinduced to synthesize pigments. On the basis of these results, pigmentation in Streptomyces is discussed.     

Induction of hyaluronic acid synthetase activity in rat fibroblasts by medium change of confluent cultures

Hyaluronic acid synthesis in cultured cells usually occurs during the growth phase. The relation between hyaluronic acid synthetase activity and cell proliferation is studied. The synthetase activity in rat fibroblasts is high during the growth phase, but low in the stationary phase. When the old medium of stationary cultures is renewed with fresh medium containing 20% calf serum, DNA synthesis occurs synchronously between 12 and 20 hours, followed by cell division. Under these conditions, the hyaluronic acid synthetase activity is significantly induced within two hours, reaching a maximum level at 5–8 hours, and then decreases gradually. This induction of the synthetase, which shows a high turnover rate, requires continued synthesis of both RNA and protein. Furthermore, the induction of both DNA and hyaluronic acid synthesis is found to be caused by calf serum added in the medium. However, dialysis and ultrafiltration of the serum permit us to concentrate an active fraction with a high molecular weight, which induces the synthetase activity, but not DNA synthesis.