scholarly journals Characterization of phospholipids accumulated in pulmonary-surfactant compartments of rats intratracheally exposed to silica

1989 ◽  
Vol 262 (3) ◽  
pp. 781-786 ◽  
Author(s):  
H Adachi ◽  
H Hayashi ◽  
H Sato ◽  
K Dempo ◽  
T Akino
Keyword(s):  
Molecular Species ◽  
Pulmonary Surfactant ◽  
Lamellar Bodies ◽  
Compositional Change ◽  
Substrate Specificities ◽  
Free Cells ◽  
Acidic Phospholipids ◽  
Silica Treatment ◽  
Intratracheal Injection

Phospholipids in the lung fractions, i.e. alveolar free cells, extracellular pulmonary surfactant, intracellular pulmonary surfactant (lamellar bodies) and microsomal fractions, of rats were examined 28 days after intratracheal injection of silica (40 mg/kg). Significant accumulations of phospholipids were observed in the extracellular- and intracellular-surfactant fractions of rats exposed to silica. The prominent phospholipid accumulated was phosphatidylcholine (PC), consisting mainly of the dipalmitoyl species. However, a compositional change in acidic phospholipids of surfactant fractions was produced by the silica treatment. The percentage of phosphatidylglycerol (PG) was significantly decreased; in contrast, that of phosphatidylinositol (PI) was increased. Thus the ratio PG/PI in the surfactant fractions was markedly decreased in response to silica. This compositional change in both acidic phospholipids occurred even in the early stages, i.e. before appreciable accumulations of alveolar phospholipids were noticed. The molecular-species profiles of both acidic phospholipids in the surfactant fractions were distinctly different from each other. The dipalmitoyl species accounted for more than 30% of PG and less than 6% of PI, respectively. These species patterns of PG and PI were similar in control and silica-treated rats. These findings suggest two possibilities that (1) PG and PI destined for pulmonary surfactant are synthesized from each specific CDP-diacylglycerol (DG) pool having different molecular species in the lung, or (2) individual enzymes responsible for synthesis of surfactant PG and PI have substrate specificities for molecular species of CDP-DG, thereby producing PG and PI having different molecular species in surfactant compartments.

scholarly journals Evidence for the regulation of guinea-pig heart microsomal phosphatidylcholine-hydrolysing phospholipase A1 by guanosine 5′-[γ-thio]triphosphate

1992 ◽  
Vol 288 (3) ◽  
pp. 965-968 ◽  
Author(s):  
K Badiani ◽  
X Lu ◽  
G Arthur
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Guinea Pig ◽  
Molecular Species ◽  
Inhibitory Effect ◽  
Phospholipase A1 ◽  
Guinea Pig Heart ◽  
Substrate Specificities ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

We have recently characterized lysophospholipase A2 activities in guinea-pig heart microsomes and postulated that these enzymes act sequentially with phospholipases A1 to release fatty acids selectively from phosphatidylcholine (PC) and phosphatidylethanolamine, thus providing an alternative route to the phospholipase A2 mode of release. In a further investigation of the postulated pathway, we have characterized the PC-hydrolysing phospholipase A1 in guinea-pig heart microsomes. Our results show that the enzyme may have a preference for substrates with C16:0 over C18:0 at the sn-1 position. In addition, although the enzyme cleaves the sn-1 fatty acid, the rate of hydrolysis of PC substrates with C16:0 at the sn-1 position was influenced by the nature of the fatty acid at the sn-2 position. The order of decreasing preference was C18:2 > C20:4 = C18:1 > C16:0. The hydrolyses of the molecular species were differentially affected by heating at 60 degrees C. An investigation into the effect of nucleotides on the activity of the enzyme showed that guanosine 5′-[gamma-thio]triphosphate (GTP[S]) inhibited the hydrolysis of PC by phospholipase A1 activity, whereas GTP, guanosine 5′-[beta-thio]diphosphate (GDP[S]), GDP, ATP and adenosine 5′-[gamma-thio]triphosphate (ATP[S]) did not affect the activity. The inhibitory effect of GTP[S] on phospholipase A1 activity was blocked by preincubation with GDP[S]. A differential effect of GTP[S] on the hydrolysis of different molecular species was also observed. Taken together, the results of this study suggest the presence of more than one phospholipase A1 in the microsomes with different substrate specificities, which act sequentially with lysophospholipase A2 to release linoleic or arachidonic acid selectively from PC under resting conditions. Upon stimulation and activation of the G-protein, the release of fatty acids would be inhibited.

Characterization of two differently glycosylated molecular species of yeast-derived hepatitis B vaccine carrying the pre-S2 region

1992 ◽  
Vol 26 (2-3) ◽  
pp. 155-162 ◽  
Author(s):  
Makoto Kobayashi ◽  
Tsuneo Asano ◽  
Kazunobu Ohfune ◽  
Koichi Kato
Keyword(s):  
Hepatitis B ◽  
Molecular Species ◽  
Hepatitis B Vaccine

scholarly journals Regiodivergent Biocatalytic Hydroxylation of L-Glutamine Facilitated by Characterization of Non-Heme Dioxygenases from Non-Ribosomal Peptide Biosyntheses

2021 ◽  
Author(s):  
Hans Renata ◽  
Emily Shimizu ◽  
Christian Zwick
Keyword(s):  
Amino Acid ◽  
Building Block ◽  
Solid Phase ◽  
Functional Characterization ◽  
Free Standing ◽  
Substrate Specificities ◽  
Total Turnover

We report the functional characterization of two iron- and a-ketoglutarate-dependent dioxygenases that are capable of hydroxylating free-standing glutamine at its C3 and C4 position respectively. In particular, the C4 hydroxylase, Q4Ox, catalyzes the reaction with approximately 4,300 total turnover numbers, facilitating synthesis of a solid-phase compatible building block and stereochemical elucidation at the C4 position of the hydroxylated product. This work will enable the development of novel synthetic strategies to prepare useful glutamine derivatives and stimulate further discoveries of new amino acid hydroxylases with distinct substrate specificities.<br>

scholarly journals Regiodivergent Biocatalytic Hydroxylation of L-Glutamine Facilitated by Characterization of Non-Heme Dioxygenases from Non-Ribosomal Peptide Biosyntheses

2021 ◽  
Author(s):  
Hans Renata ◽  
Emily Shimizu ◽  
Christian Zwick
Keyword(s):  
Amino Acid ◽  
Building Block ◽  
Solid Phase ◽  
Functional Characterization ◽  
Free Standing ◽  
Substrate Specificities ◽  
Total Turnover

We report the functional characterization of two iron- and a-ketoglutarate-dependent dioxygenases that are capable of hydroxylating free-standing glutamine at its C3 and C4 position respectively. In particular, the C4 hydroxylase, Q4Ox, catalyzes the reaction with approximately 4,300 total turnover numbers, facilitating synthesis of a solid-phase compatible building block and stereochemical elucidation at the C4 position of the hydroxylated product. This work will enable the development of novel synthetic strategies to prepare useful glutamine derivatives and stimulate further discoveries of new amino acid hydroxylases with distinct substrate specificities.<br>

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