Prediction of sequential antigenic regions in proteins

Prediction of antigenic regions in a protein will be helpful for a rational approach to the synthesis of peptides which may elicit antibodies reactive with the intact protein. Earlier methods are based on the assumption that antigenic regions are primarily hydrophilic regions at the surface of the protein molecule. The method presented here is based on the amino acid composition of known antigenic regions in 20 proteins which is compared with that of 314 proteins [(1978) Atlas of Protein Sequence and Structure, vol. 5, suppl. 3, 363-373]. Antigenicity values were derived from the differences between the two data sets. The method was applied to bovine ribonuclease, the B-subunit of cholera toxin and herpes simplex virus type 1 glycoprotein D. There was a good correlation between the predicted regions and previously determined antigenic regions.     

Role of the modulator protein in the interconversion of rabbit skeletal muscle protein phosphatase

The major active protein phosphatase present in a rabbit skeletal muscle extract is associated with the glycogen particle and migrates in sucrose density gradient centrifugation as a Mr = 70,000 protein and contains modulator activity. Addition of extra modulator protein causes a time- and concentration-dependent conversion of the enzyme to an inactive FA-ATP, Mg-dependent form. The intrinsic modulator in the active phosphatase is destroyed by limited proteolysis without an appreciable change in the phosphatase activity. The proteolyzed active enzyme has a lower molecular weight (Mr = 40,000) and it reassociates with the modulator producing a FA-ATP, Mg-dependent enzyme form (Mr = 60,000). The modulator protein is used stoichiometrically in the activation of the ATP, Mg-dependent phosphatase. This is in agreement with the presence of one unit of modulator activity per unit of native spontaneously active phosphatase.     

Maximal oxygen uptake in Danish adolescents 16-19 years of age

A random sample of schoolchildren, 119 boys and 153 girls, was tested in the fall of 1983. The data presented here are anthropometric data (height, weight, fat % and vital capacity) and oxygen uptake directly measured on a bicycle ergometer. The mean height and weight for boys were 179.1 cm and 67.7 kg, and those for girls were 168.0 cm and 59.6 kg. The mean fat content was 9.1% for boys and 19.1% for girls, and their mean vital capacities were 4.91 and 3.61 respectively. The boys had a high maximal oxygen uptake (51.7 ml X kg-1 X min-1) showing no reduction over the age span studied. The girls' maximal oxygen uptake was lower (overall mean 40.0 ml X kg-1 X min-1) with a small reduction from 16 to 19 years of age. When comparing maximal oxygen uptake per kg lean body mass in the two sexes, the boys had 18.4% higher values than the girls, indicating that girls of this age have the lower fitness level. The results of maximal aerobic power measurement in the boys compare well with findings from other investigations using direct measurements, indicating that the fitness of teenage boys is kept at a high level. Comparable data from various countries for girls show different pictures, but it appears that in general they have a low fitness level.     

On the heterogeneous glycosylation of the membranes of the trans Golgi network in rabbit luteal cells

In rabbit luteal cells the transmost element (G2) of the Golgi apparatus bears cytochemical resemblances to the limiting membrane of lysosomes and it was suggested that lysosomal membranes may originate from the above element. But in the normal Golgi apparatus it cannot be made out whether the considered molecules are indeed membrane bound. Perfusing the rabbit ovary with buffer containing monensin or ammonium chloride allowed to vesiculate the trans Golgi network (G2-G1) selectively. Controls showed a well-preserved ultrastructure. Parts of the limiting membrane of the vacuoles derived from the transmost reticulum (G2) were spiny coated and carried an osmiophilic inner layer. They also showed a heavy precipitate for acid phosphatase (AcPase) and were strongly stained with phosphotungstic acid (PTA) at low pH. By neutralizing the acidic groups, involved in the PTA-staining, it was possible to show that the same membranes were more heavily glycosylated. The MvB's and the limiting membrane of lysosomes showed the same staining characteristics. The other membrane domains revealed a gradient in PTA staining and in AcPase activity. It is concluded that the trans Golgi network (G2-G1) is an acidic compartment. The presence of differentially glycosylated membranes reveals a sorting mechanism for membranous components. The highly glycosylated membrane stretches seem to be involved in endocytosis and in the formation of lysosomal membranes.     

Metyrapone - reduced cytochrome P-450 complex: A specific method for the determination of the phenobarbital inducible form of rat hepatic microsomal cytochrome P-450

Using homogeneous cytochrome P-450, we have shown that the well-known metyrapone-dithionite reduced cytochrome P-450 complex is specific for the cytochrome P-450b induced by phenobarbital. A linear relationship was observed between the absorbance of metyrapone-reduced cytochrome P-450 complex and the one of CO-reduced cytochrome P-450 complex, the usual method for the determination of cytochrome P-450. A method has been proposed for the specific determination of the cytochrome P-450b.