The International journal of biochemistry最新文献

1. alpha 1-Thiol proteinase inhibitor (alpha 1 TPI) purified from outdated human plasma was a glycoprotein with Mr 83,000 and was composed of heavy and light chains held together with a disulfide bond. 2. The data on amino acid composition, amino terminal sequence of the light chain and carboxyl terminal sequences of the heavy and light chains indicate that alpha 1 TPI is identical with kinin- and fragment 1.2-free HMW kininogen. 3. Purified human plasmin generated a derivative having the same molecular weight (Mr 83,000), same subunit structure (heavy and light chains) and same inhibitory capacity as alpha 1 TPI from HMW kininogen and kinin-free HMW kininogen. This indicated the possibility that alpha 1 TPI is derived from HMW kininogen by plasmin.

1. Conventional DNA extraction procedures have failed to release free DNA from the chick embryo fibroblast cytosolic DNA-RNA complexes. 2. Free DNA has been released only from the smallest cell cytosol DNA fraction, which is not in the native state associated with RNA: it is very small (of the order of 100 bases) and single stranded. 3. However, phenol extraction does separate complex DNA-associated material from the RNA which has invariably been found to accompany it in all but the smallest fraction (see 2 above). 4. The principal factor preventing DNA release appears to be a massive aggregation of partially purified DNA-associated material.

1. Protein kinase C (PK-C) from the rat parotid gland has been partially purified and characterized for the first time. During its purification, this enzyme exhibited the same chromatographic behavior as the rat brain enzyme. 2. Affinities for phosphatidylserine (3 micrograms/ml), ATP (8 microM) and calcium (8 microM) were determined kinetically and found to be similar for the enzymes from each tissue. 3. Experiments designed to detect agonist-stimulated translocation of PK-C activity during phosphatidylinositol turnover found no change in levels of soluble PK-C, suggesting that PK-C translocation may not be an obligatory correlate of its activation. The implications of this result are discussed.

1. Tyrosine and two structural isomers of histidine residues in human haptoglobin were modified with diazotized sulfanilic acid. Sulfanilazo-derivatives of haptoglobin obtained by increasing the reagent/protein molar ration showed gradual decrease of peroxidase activity when complexed with hemoglobin. 2. Formation of haptoglobin derivatives with ten mono(sulfanilazo)-tyrosines and two mono (sulfanilazo)histidines resulted in the blockage of one out of six antigenic determinants, whereas immunoreactivity of the derivative with fourteen azotyrosines, one C-4, and two C-2 azohistidines was decreased by half. 3. Removal of sialic acid from oligosaccharide chains of haptoglobin made the molecule more accessible to diazotized sulfanilic acid. 4. Sulfanilazo-modification of tyrosine and histidine residues was practically of no effect in the reaction of haptoglobin with plant lectin, concanavalin A.

1. The polysaccharide and glycolipid composition in Tritrichomonas foetus was studied by paper, thin-layer and gas-liquid chromatographic analysis. 2. The carbohydrate components of the polysaccharide were glucose (47%), galactose (34%) and mannose (19%). N-acetylneuraminic acid was the sialic acid derivative characterized in the flagellate whole cells. 3. The sialic acid density was estimated as 2.7 x 10(7) residues/cell. 4. The long-chain base dihydrosphingosine, the carbohydrates galactose (67%), glucose (21%) and mannose (12%) as well as the fatty acids myristic (48%) and palmitic (52%) acids were characterized as components of the total glycolipids of T. foetus. 5. Total glycolipids were fractionated: a galactocerebroside and a ganglioside were identified.

1. In chicken embryo cartilage putrescine levels, maximal at day 8, fall by day 16 to a four-fold lower value, which remains unchanged through hatching and in the 12-day-old chick. 2. Spermine and spermidine, initially higher than putrescine, are almost halved between days 8 and 11, and remain constant afterwards. 3. Ornithine decarboxylase is down to 20% of the day 8 value by day 16, and is further reduced in the newly hatched chick. 4. S-Adenosyl-methionine decarboxylase activity shows a 50% reduction between days 8 and 11, and no further changes. 5. Spermidine acetyltransferase activity at day 11 is 30% lower than at day 8, goes back up to the initial level by day 16, and progressively decreases through hatching and the first 12 days of life.

1. Cytotoxin homologues S3C2 and S4C8 from Aspidelaps scutatus were purified by gel filtration and ion exchange chromatography. 2. They consist of 63 amino acids including eight half-cystines. The toxicities of S3C2 and S4C8 were determined and LD50 values of 6.6 and 9.4 micrograms/g mouse were, respectively, found. 3. The complete primary structures of toxins S3C2 and S4C8 have been determined. The two toxins resemble the cytotoxin type toxins and in the cytotoxin homologues the ten structurally invariant amino acids of the neurotoxins and the cytotoxins are conserved.

1. The effect of exercise (2 hr treadmill running at 28 m/min) on PDHa (the activity of the active form of pyruvate dehydrogenase) in untrained rats, trained rats (2 hr/d at 25 m/min for 4 wk), and in 24 hr fasted rats was determined. 2. Exercise increased PDHa activity approximately 2 fold in fed-untrained rats. 3. Fasting decreased PDHa activity in sedentary rats to approximately half the activity in fed rats. 4. The increase in PDHa activity during exercise was less in fasted than fed rats. 5. Training did not change the total activity of PDH (phosphorylated plus nonphosphorylated forms) but the percent of PDH in the active form was increased in muscle of trained-rested rats. 6. PDHa activity was unchanged by acute exercise (2.5 hr at 40 m/min) in the trained rats.

1. alpha- and beta-Adrenergic agonists as well as insulin stimulate 3-O-methyl-D-glucose efflux by the perfused rat heart and increase D-glucose inhibitable cytochalasin B binding by isolated sarcolemma. 2. alpha- and beta-Agonists like insulin increase Vmax for 3-O-methyl-D-glucose efflux and increase Bmax for cytochalasin B binding. 3. The effects of alpha- and beta-agonists are totally Ca2+-dependent whilst those of insulin appear to be only partly Ca2+-dependent.

1. We evaluated the influence of cigarette smoking on arterial wall membranes, using Na+-K+-ATPase activity, free cholesterol (FC) and phospholipid (PL) contents as indices of membrane structural and functional integrity. 2. Segments of aorta, carotid and femoral arteries were obtained from normal dogs (controls) and dogs subjected to chronic cigarette smoking for 2 yr (12 cigarettes a day). 3. Na+-K+-ATPase activity was assessed in segments of carotid and femoral arteries using a ouabain-sensitive 86Rb uptake procedure for intact tissues. 4. Free cholesterol and phospholipids were separated, identified, and quantitated from extracts of aortic samples by means of two dimensional thin-layer chromatography. 5. Na+-K+-ATPase activity was reduced in the smoker group in both carotid and femoral arteries. This reduced enzyme activity was accompanied by a rise in cell Na+ levels at both arterial sites. 6. Aortic FC was elevated and the PL profile was altered in the smoker group; as a result, phosphatidylcholine was reduced, whereas lysophosphatidylcholine, phosphatidic acid, and cardiolipin were elevated. 7. Phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and sphingolipid levels were unchanged. In addition, the FC/PL ratio was increased in the smokers. 8. Taken together, the changes in Na+-K+-ATPase activity, FC/PL ratio and phospholipid profiles observed are consistent with the hypothesis that chronic cigarette smoking causes a reorganization of the phospholipid bilayer in the smooth-muscle cell membrane of the arterial wall.