Enzymatic sulfation of galactosyl- and lactosylceramides in cell lines derived from renal tubules.

1. The renal cell lines, JTC-12 and MDCK, not only synthesize galactosylceramide 3-sulfate and lactosylceramide 3'-sulfate in vivo, but also contain enzymes that catalyze the transfer of sulfate to galactosylceramide and lactosylceramide in vitro. 2. Concentration of cations necessary for maximum sulfotransferase activity occurred at 40 mM Ca2+ with galactosylceramide and 15 mM Ca2+ with lactosylceramide as the substrate. Na+ was also found to stimulate the sulfation of galactosylceramide, but was slightly inhibitory for the sulfation of lactosylceramide. 3. The products of the in vitro assay mixture were characterized as galactosylceramide 3-sulfate and lactosylceramide 3'-sulfate by a variety of TLC separations. 4. The apparent Km of JTC-12 cells for galactosylceramide was 17 microM, while that for lactosylceramide was 82 microM. The Km values of MDCK cells were comparable to those of JTC-12 cells. Competition studies suggested that galactosylceramide and lactosylceramide were sulfated by a single enzyme in both cell lines.     

Sequence and over-expression of subunits of adenosine triphosphate synthase in thermophilic bacterium PS3

The primary structures of all the subunits of thermophilic ATP synthase were determined, and its alpha, beta and gamma subunits could be over-expressed in Escherichia coli, because these subunits were stable and reconstitutable. DNA of 7500 base pairs in length was found to contain a cluster of nine genes for subunits of ATP synthase. The order of their reading frames (size in base pairs) was: I(381): a(630): c(216): b(489): delta(537): alpha(1507): gamma(858): beta(1419): epsilon(396), I being a gene for a small hydrophobic, basic protein expressed in vitro. All the termini of TF0F1 subunits were confirmed by peptide sequencing. Large quantities of the overexpressed thermophilic alpha, beta and gamma subunits were prepared from the extract of E. coli, by a few purification steps.     

Characterization of sulfoglycosphingolipids by direct probe electron impact mass spectrometry

Novel mono- and bis-sulfoglycolipids, monosulfogangliotriaosylceramide, bis-sulfogangliotriaosylceramide, and bis-sulfogangliotetraosylceramide, were recently isolated from rat kidney. These sulfoglycolipids and their partially- or fully-desulfated products were characterized by direct probe electron impact mass spectrometry as permethylated derivatives. The fragment ions obtained from permethylated-fully-desulfated-remethylated glycolipids included ions containing up to four monosaccharides plus C-1 and C-2 of acylated sphingoids as well as those plus C-1 to C-3 of acylated sphingoids. By the use of trideuteriomethyl iodide instead of methyl iodide in the remethylation step after desulfation, the sequences of the monosaccharides containing the sulfate ester were established. When the sulfate ester was present, the intensity of the ions derived from the carbohydrate moiety was much weaker in comparison to that of those from the permethylated-fully desulfated derivative. Instead, the intensity of the fragments from the ceramide moiety was very strong in the presence of the sulfate ester.     

Isolation and identification of 1 alpha,25-dihydroxy-24-oxovitamin D3, 1 alpha,25-dihydroxyvitamin D3 26,23-lactone, and 1 alpha,24(S),25-trihydroxyvitamin D3: in vivo metabolites of 1 alpha,25-dihydroxyvitamin D3

Three new in vivo metabolites of 1 alpha,25-dihydroxyvitamin D3 were isolated from the serum of dogs given large doses (two doses of 1.5 mg/dog) of 1 alpha,25-dihydroxyvitamin D3. The metabolites were isolated and purified by methanol-chloroform extraction and a series of chromatographic procedures. By cochromatography on a high-performance liquid chromatograph, ultraviolet absorption spectrophotometry, mass spectrometry, Fourier-transform infrared spectrophotometry, and specific chemical reactions, the metabolites were identified as 1 alpha,25-dihydroxy-24- oxovitamin D3, 1 alpha,25-dihydroxyvitamin D3 26,23-lactone, and 1 alpha,24(S),25-trihydroxyvitamin D3. According to these procedures, the total amounts of the isolated metabolites were as follows: 1 alpha,25-dihydroxyvitamin D3, 23.6 micrograms; 1 alpha,25-dihydroxy-24- oxovitamin D3, 1.8 micrograms; 1 alpha,25-dihydroxyvitamin D3 26,23-lactone, 9.2 micrograms; 1 alpha,24(R),25-trihydroxyvitamin D3, 15.4 micrograms; 1 alpha,24(S),25-trihydroxyvitamin D3, 1.0 microgram. With recovery corrections, the serum levels of each metabolite were approximately 49 ng/mL for 1 alpha,25-dihydroxyvitamin D3, 3.7 ng/mL for 1 alpha,25-dihydroxy-24- oxovitamin D3, 19 ng/mL for 1 alpha,25-dihydroxyvitamin D3 26,23-lactone, 32 ng/mL for 1 alpha,24(R),25-trihydroxyvitamin D3, and 2.1 ng/mL for 1 alpha,24(S),25-trihydroxyvitamin D3.     

Synthesis and biological activity of (22E,25R)- and (22,25S)-22-dehydro- 1 alpha,25-dihydroxy-26-methylvitamin D3

Both 25-epimers of (22E)-22-dehydro-1 alpha,25-dihydroxy-26-methylvitamin D3 [22-dehydro-26-methyl-1,25-(OH)2D3] were synthesized. The biological activity of these compounds was tested in binding affinity to chick intestinal receptor protein of 1 alpha,25-dihydroxy-vitamin D3 [1,25-(OH)2D3] and in stimulating for intestinal calcium transport and bone calcium mobilization with vitamin D-deficient rats. The relative potency of (25R)- and (25S)-22-dehydro-26-homo-1,25-(OH)2D3 and 1,25-(OH)2D3 in competing for the intestinal cytosolic binding was 1.7:1.5:1. A similar order of activity was observed on intestinal calcium transport and bone calcium mobilization. In the ability for stimulation of intestinal calcium transport, (25R)- and (25S)-22-dehydro-26-methyl-1,25-(OH)2D3 were about 3.6 and 2.1 times as active as 1,25-(OH)2D3, respectively. In bone calcium mobilization tests, (25R)- and (25S)-22-dehydro-26-methyl-1,25-(OH)2D3 were estimated to be 2.2 and 1.6 times as potent as 1,25-(OH)2D3, respectively.     

Effects of body and head positions on bilateral difference in tympanic temperatures

We have examined the nonparallel changes in tampanic membrane temperatures (T _ty) from the two ears in response to various changes in body and head positions. Upon assuming a lateral recumbent position, the T _ty on the lower side increased while that on the upper side decreased. Pressure application over a wide area of the lateral chest only caused inconsistent and obscure asymmetric changes in T _ty. A lateral flexion of the head with the subject sitting upright and a rotation of the head to the side in a supine position induced an increase in the T _ty on the lower side compared to that on the upper side. The temperature and blood flow of the forehead often decreased on the lower side and increased on the upper side, although such responses were not always concomitant with the asymmetric changes in T _ty. A dorsal flexion of the head with the subject in a reclining position caused a slight increase in the T _ty, whereas raising the head upright induced a slight decrease in them. Two additional experiments were carried out with single photon emission computed tomography using ^99mTc-hexamethylpropyleneamine oxime as tracer, and a slight, relative decrease in counts was noted in the right hemisphere during rotation of the head to the right. These results would strongly suggest that unilateral increases and decreases in T _ty could have been caused by one-sided decreases and increases, respectively, in blood flow to the brain and/or the tympanic membrane, induced by a vasomotor reflex involving vestibular stimulation.     

Nucleotide sequence of the gene coding for four subunits of cytochrome c oxidase from the thermophilic bacterium PS3

The gene coding for four subunits of cytochrome aa3-type oxidase was isolated from a genomic DNA library of the thermophilic bacterium PS3 and sequenced. The N-terminus of each subunit was also sequenced to verify the initiation site of the reading frame. The deduced amino acid sequences contained 615 amino acid residues for subunit I (CO1/caaB product), 333 residues for subunit II (CO2/caaA product), 207 residues for subunit III (CO3/caaC product), and 109 residues for subunit IV (CO4/caaD product) after processing. Re-examination of the sequencing of caa revealed a longer open reading frame for CO1, which contains 14 transmembrane segments instead of 12 [Sone et al. (1988) J. Biochem. 103, 606-610], although the main portions of the sequences constituting cytochrome a (FeA), cytochrome a3 (FeB), and CuB are correct. PS3 CO2 has an additional sequence for cytochrome c after the CuA binding protein portion with 2 transmembrane segments, which is homologous to the mitochondrial counterpart. PS3 CO3 has DCCD-binding glutamyl residues but contains only 5 transmembrane segments, unlike the mitochondrial counterpart, which has 7 segments. The subunits of PS3 cytochrome oxidase (aa3-type) show clear similarity in amino acid sequences with those of cytochrome bo-type oxidase from Escherichia coli as well, in spite of the difference of hemes. PS3 CO3 and CO4 are much more similar to E. coli CO3 and CO4 than to mitochondrial CO3 and CO4, respectively.