Solubility of phosphatidylcholine in chloroform. Formation of hydrogen bonding between phosphatidylcholine and chloroform

The solubility of phosphatidylcholine (PC) was studied by the spectroscopic analysis and the measurement of the solubility. The qualitative analysis of infrared absorptionspectra confirmed the existence of two types of hydrogen bondings between chloroform and PC, one between chloroform and the CO group of PC and the other between chloroform and the phosphorylcholine group of PC. The quantitative analysiss of the C6 stretching vibration bands of the chloroform-d solution of PC showed that the latter hydrogen bonding mainly contributes to the solubility and that PC dissolves in chloroform to form a complex consisting of a few or more molecules of chloroform and one molecule of PC. We discussed in this report about the molecular organization of PC in chloroform solution.     

Distribution of rhodopsin and retinochrome in the squid retina

The cephalopod retina contains two kinds of photopigments, rhodopsin and retinochrome. For many years retinochrome has been thought to be localized in the inner segments of the visual cells, whereas rhodopsin is in the outer segments. However, it is now clear that retinochrome can be extracted also from fragments of outer segments. In the dark-adapted retina of Loligo pealei retinochrome is distributed half-and-half in the inner and outer segments. Todarodes pacificus contains much more retinochrome than Loligo, and it is more abundant in the outer than in the inner segments. The outer segments of Loligo contain retinochrome and metarhodopsin in addition to rhodopsin, whether squids are kept in the dark or in the light. But there is extremely little metarhodopsin (about 3% of rhodopsin) even in light-adapted eyes. The inner segments contain only retinochrome, and much less in the light than in the dark. On the other hand, retinochrome in the outer segments increases markedly during light adaptation. These facts suggest the possibility that some retinochrome moves forward from the inner to the outer segments during light adaptation and there reacts with metarhodopsin to promote regeneration of rhodopsin.     

Effects of catecholamines on the lipolysis of two kinds of fat cells from adult rabbit.

The administration of various catecholamines and adrenocorticotropic hormone to adult rabbit elevated plasma glycerol concentration. These catecholamines also induced the in vitro lipolysis of isolated interscapular fat cells but could not bring about the lipolysis of epididymal ones, while adrenocorticotropic hormone induced the lipolyses of both kinds of fat cells. It may be speculated from these results that catecholamines liberated endogenously in adult rabbit cannot act on all systemic adipose tissues but have lipolytic effects on a part of them.     

Establishment and characterization of a human squamous cell carcinoma cell line LK-52 which produce direct activator of coagulant factor X]

Uterus origin squamous cell carcinoma cell line LK-52 was established from surgical specimen of lung metastatic nodule. LK-52 produce poorly differentiated squamous carcinoma in nude mouse, and doubling time in vitro was 38 hours. Chromosome analysis show various abnormality and main mode number was 67 and 68. LK-52 shed active procoagulant substance into culture medium. The culture medium of LK-52 shortening recalcification time of normal human plasma and factor VII or factor IX deficient plasma but not factor X deficient plasma. Procoagulant activity of LK-52 product may induced with direct activation of coagulant factor X. Procoagulant activity which produced by cancer cell may play a important roll in the unbalanced haemostasis of cancer patient.     

Enhanced leukotriene C4 synthase activity in thioglycollate-elicited peritoneal macrophages

The utilization of LTA4 by peritoneal macrophages (MO) obtained from untreated rats (control) as well as by those elicited from rats was investigated at designated intervals (on days 3, 7, and 14) following the intraperitoneal injection of thioglycollate (TG). On day 7 following the injection the elicited MO converted LTA4 to LTC4 at the highest rate while the resident MO showed the lowest rate. The conversion of LTA4 to LTC4 and LTB4 was next examined by using each MO lysate. The apparent LTC4 synthase activity was significantly higher in the MO lysate both on day 3 and day 7, with the latter being the highest value obtained. The GSH S-transferase activity in each lysate using as the substrate, DNCB was significantly lower on day 3 but significantly higher on day 7 as compared to control values. However, this elevated activity was less variable than that observed with LTC4 synthase. The possible implication for these observations is discussed.     

A monoclonal antibody against a native conformation of the porcine renal Na+/K(+)-ATPase alpha-subunit protein

A monoclonal antibody (mAb50c) against the native porcine renal Na+/K(+)-transporting adenosinetriphosphatase (EC 3.6.1.37, ATP phosphohydrolase) (Na+/K(+)-ATPase) was characterized. The antibody could be classified as a conformation-dependent antibody, since it did not bind to Na+/K(+)-ATPase denatured by detergent and its binding was affected by the normal conformational changes of the enzyme induced by ligands. The binding was the greatest in the presence of Na+, ATP or Mg2+ (E1 form), slightly less in the presence of K+ (E2K form) and the least when the enzyme was phosphorylated, especially in the actively hydrolyzing form in the presence of Na+, Mg2+ and ATP. The antibody inhibited both the Na+,K(+)-ATPase activity and the K(+)-dependent p-nitrophenylphosphatase activity by 25%, but it had no effect on Na(+)-dependent ATPase activity. The antibody partially inhibited the fluorescence changes of the enzyme labeled with 5'-isothiocyanatofluorescein after the addition of orthophosphate and Mg2+, and after the addition of ouabain. Proteolytic studies suggest that a part of the epitope is located on the cytoplasmic surface of the N-terminal half of the alpha-subunit.     

The role of protein kinase C in LH release

To investigate the postreceptor mechanism, especially the role of protein kinase C (C-kinase), in luteinizing hormone (LH) release from anterior pituitary cells, dispersed rat anterior pituitary cells were stimulated with luteinizing hormone-releasing hormone (LH-RH), [D-Ser(tBu)]6 des-Gly-NH2(10) ethylamide (Buserelin), 12-0-tetradecanoyl phorbol-13-acetate (TPA) and trifluoperazine (TFP) and the LH released into the medium was determined by radioimmunoassay. LH released by combined stimulation with TPA and either LH-RH or Buserelin was significantly less than that released by LH-RH or Buserelin alone (LH-RH: p less than 0.05; Buserelin: p less than 0.01). It is thought that this paradoxical phenomenon occurred due to desensitization accompanied by down-regulation of LH-RH receptors induced by TPA. This hypothesis was supported by the finding indicating that the binding capacity of LH-RH receptors decreased in a time-course manner during incubation with TPA. The amount of LH released by combined stimulation with TPA and TFP was significantly greater than with TPA alone (P less than 0.01). This suggests that TFP has dual actions, i.e., facilitating and inhibiting LH release.     

Isolation of proteins with carbonyl reductase activity and prostaglandin-9-ketoreductase activity from chicken kidney

Kidney has the greatest capacity among the tissues of chicken for reducing aromatic ketones, and two ketone reductases were separated from this tissue by DEAE-cellulose chromatography and isolated. Though both are monomeric proteins with a molecular weight of 29,500, and with similar amino acid compositions and immunological properties, they differ in their pI values. The two enzyme species show no apparent difference in catalytic properties; aromatic ketones, aldehydes and quinones are reduced at high rates and alicyclic ketones such as 3-ketosteroids and prostaglandin E2 at low rates. The substrate affinity for several representative substrates at pH 7.2 is higher than that at the optimal pH of 6.3. Both enzymes prefer NADPH to NADH as a cofactor. Low NADP+-dependent reverse reactions occur with 9- and 15-hydroxyprostaglandins and certain alcohols as substrates. The enzymes show similar sensitivities to heavy metal ions, SH-reagents, quercitrin, indomethacin, and FMN.     

Membrane glycoprotein synthesis: cleavage of the signal sequence in the absence of glycosylation

The controlled action of trypsin on porcine pancreatic procarboxypeptidase A releases a large activation peptide which contains the activation segment of the proenzyme. Circular dichroism studies indicate that the isolated activation peptide contains a high percentage of residues in ordered secondary structures (mainly α-helix). This result agrees with predictions of secondary structure carried out on the published amino acid sequence of the homologous rat proenzyme. Moreover, proton magnetic resonance spectroscopy shows that the peptide adopts a thermostable tertiary structure with characteristics typical of globular proteins. The results as a whole indicate that the activation segment of porcine pancreatic procarboxypeptidase A constitutes a folded structural domain.     

Elimination of plasmid-linked polyglutamate production by Bacillus subtilis (natto) with acridine orange.

Treatment of Bacillus subtilis (natto) strains Asahikawa, F, and M with acridine orange resulted in the conversion of approximately 64.2% of the Asahikawa population, 22.4% of the F population, and 9.2% of the M population to polyglutamate-nonproducing colonies. Such curing is suggestive of the involvement of plasmid DNA. Samples of cleared lysates of both parental and their cured strains were subjected to agarose gel electrophoresis to determine the plasmid composition. Parental strains were found to possess a plasmid, but polyglutamate-nonproducing derivatives were missing the plasmid. The plasmid-linked polyglutamate production, which was originally isolated from B. subtilis (natto), could be transformed in B. subtilis.