1,721,118 research outputs found
BINDING OF DIAZEPAM, SALICYLIC-ACID AND DIGITOXIN TO ALBUMIN ISOLATED FROM FETAL AND ADULT SERUM
No full textAlbumin was isolated from pooled fetal serum obtained at normal delivery at term and from pooled adult plasma. Albumin isolation was carried out by means of PEG precipitation followed by ion exchange chromatography on DEAE-Sephadex A 50 and then on SP-Sephadex C 50. The binding of diazepam (1-mu-M, salicylic acid (2 mM) and digitoxin (6 nM) to albumin (40 g/l) was measured by equilibrium dialysis at 37-degrees-C. The unbound fraction (mean +/- SD) for fetal and adult albumin of diazepam was 1.86 +/- 0.24 and 1.82 0.15% (NS), that of digitoxin was 3.18 +/- 0.27 and 3.36 +/- 0.04% (NS) and that of salicylic acid was 11.65 +/- 0.99 and 9.47 +/- 0.75% (p < 0.05), respectively. With both fetal and adult albumin, a single class of binding sites was observed for diazepam and digitoxin, whereas two classes of binding sites were observed for salicylic acid. The number of binding sites (n, moles of drug per mole of albumin) for fetal and adult albumin was 0.83 and 1.02 for diazepam and 0.014 and 0.018 for digitoxin, respectively. For salicylic acid, n was 1.45 (fetal albumin) and 1.55 (adult albumin) for the higher affinity site, and 3.06 (fetal albumin) and 3.27 (adult albumin) for the lower affinity site. The association constant (K(a), M-1) for diazepam was 1.36 X 10(5) (fetal albumin) and 1.00 X 10(5) (adult albumin) and that for digitoxin was 4.12 X 10(6) (fetal albumin) and 2.7 X 10(6) (adult albumin). For salicylic acid, K(a) was 38.4 X 10(3) (fetal albumin) and 35.8 X 10(3) (adult albumin) for the higher affinity site, and 2.7 X 10(3) (fetal albumin) and 4.3 X 10(3) (adult albumin) for the lower affinity site. This work shows that fetal and adult albumin have similar binding properties and corroborates our previous findings with furosemide
DIFFERENTIAL DISTRIBUTION OF PHENOL AND CATECHOL SULFOTRANSFERASES IN HUMAN LIVER AND INTESTINAL-MUCOSA
No full text
DISTRIBUTION OF UDP-GLUCURONOSYLTRANSFERASE AND ITS ENDOGENOUS SUBSTRATE URIDINE 5'-DIPHOSPHOGLUCURONIC ACID IN HUMAN TISSUES
No full textThe activity of UDP-glucuronosyltransferase (UDPGT) and the concentration of its endogenous substrate, 5'-diphosphoglucuronic acid (UDPGA), have been measured in human liver, kidney, lung and intestinal mucosa. The activity of UDPGT was tissue- and substrate-dependent. The liver/kidney and liver/intestine ratios for UDPGT varied over one order of magnitude with three substrates. The highest activity of UDGPT in extrahepatic tissues was in the kidney, with 1-naphthol as substrate; it was about half of the hepatic activity The concentration (mu-mol.kg-1) of UDPGA was 279 (liver), 17.4 (kidney), 19.3 (intestinal mucosa) and 17.2 (lung), it was at least 15-fold higher in liver than the other tissues, and the concentration in kidney, lung and intestinal mucosa was similar. The kinetics of UDPGT in a liver homogenate at varying concentrations of UDPGA and fixed concentration of 1-naphthol, ethinyloestradiol, and morphine was also measured. The apparent k(m) for UDPGT depended upon the chemical nature of the UDPGA-acceptor substrate; average values of k(m) were 63, 300, and 700-mu-mol.l(-1) for 1-naphthol, ethinyloestradiol and morphine respectively These values are, respectively, lower, similar to and higher than the hepatic concentration of UDPGA. Under certain circumstances UDPGA may be the limiting factor in the in vivo glucuronidation of drugs by extrahepatic tissues
From a dull enzyme to something else: facts and perspectives regarding aldose reductase
No full textAldose Reductase (ALR2) is defined as the first enzyme of the "polyol pathway". As such, ALR2 would convert glucose to sorbitol through an NADPH dependent reaction. Considered a promoter of osmotic imbalance under hyperglycemic conditions, the enzyme has been under intense investigation as a critical target to prevent and control diabetic complications through the inhibition of its activity. Further characterization of ALR2 suggests its participation in cell detoxification mechanisms through the reduction of toxic aldehydes. Moreover, intriguing is the apparent involvement of the enzyme in the signalling machinery of inflammatory cell response. Here, the structural and functional assessment of ALR2 as an aldose/aldehyde reducing enzyme, and its involvement in various aspects of cell function from sugar metabolism to redox homeostasis and cell signaling are presented
Thiol dependent oxidation of enzymes: the last chance against oxidative stress
No full text1. A survey of known effects of oxidized thiols on enzyme activity reveals a potential concerted action on metabolic pathways determining an impairment of anabolic reduction processes and an activation of the oxidative arm of the hexose monophosphate shunt. Thus it appears that, following oxidative stress, the increase of disulphides may act in restoring a reduced state in the cell by specifically channelling the metabolic energy flux
Hirunorms, novel hirudin-like direct thrombin inhibitors
No full text1. Hirunorms are new synthetic peptides designed to interact with thrombin in a similar way to the natural inhibitor hirudin. 2. Hirunorms are specific and efficient in vitro inhibitors of thrombin activity. 3. Hirunorms are potent anticoagulant and antithrombotic agents in in vivo experimental models devoid of hemorrhagic effects at doses that are active in preventing thrombosis. (C) 1998 Elsevier Science Inc
SULFOTRANSFERASE AND ITS SUBSTRATE - ADENOSINE-3'-PHOSPHATE-5'-PHOSPHOSULPHATE IN HUMAN-FETAL LIVER AND PLACENTA
No full textThiol and disulfide determination by free zone capillary electrophoresis.
No full textA rapid, sensitive and simple method for the determination of reduced and oxidized glutathione, cysteine, cystine, cysteamine, cystamine and their respective mixed disulfides is described. The compounds were separated and identified in a single step by capillary zone electrophoresis. The method was used to follow the thiol-disulfide interconversion and to measure glutathione levels in lens extracts
- …
