Amphotericin B delays both scrapie agent replication and PrP-res accumulation early in infection.

Amphotericin B delays the onset of clinical symptoms in hamsters infected with scrapie agent strain 263K. Here we show that accumulation of a scrapie-specific isoform of the prion protein (PrP-res) and agent replication were delayed early in amphotericin B-treated animals. By 8 weeks postinfection, only untreated animals exhibited clinical symptoms of scrapie infection whereas PrP-res levels and titers were similar in treated and untreated animals. This suggests that although PrP-res accumulation and agent replication are linked, they are not the sole factors required for the onset of clinical disease.

Multiple mitochondrial DNA deletions associated with age in skeletal muscle of rhesus monkeys.

We have examined skeletal muscle for the presence of age-associated mitochondrial DNA (mtDNA) deletions from 16 rhesus monkeys (age range 6-27 years). All animals over 13 years of age contained potential mtDNA deletions, whereas the presence of deletions was greatly reduced or absent in younger animals. The specific deletion patterns varied from individual to individual. Numerous mtDNA deletions accumulate with age in skeletal muscle from a nonhuman primate, indicating that the rhesus monkey may provide an excellent animal model to study mtDNA deletions. Further, the existence of multiple mtDNA deletions supports the possibility that they may contribute to geriatric muscular deficits, which are nearly universal in occurrence yet poorly understood.

The protein inhibitors of amylases and peptidases isolated from cereal grains.

The peptidase and amylase inhibitors were isolated from rye and preliminarily purified to investigate some of their properties. It was shown, that both are of albumin character despite the acetic acid solubility of the former. They are not active against the native cereal grain peptidases or amylases (rye, wheat, triticale) but the latter inhibited the animal (hog pancreas, man salivary) and bacterial (Thermamyl, NOVO) alpha-amylases. In the long-term experiments on various rye genotypes there was shown, that the peptidase inhibitor level was rather differentiated between them, but more stable as concerns particular ones. On the other hand the level differentiation of alpha-amylase inhibitor between the genotypes was rather small, but that of climate much more significant.

Plant tRNA nucleotidyltransferase : I. Isolation and purification of tRNA nucleotidyltransferase from Lupinus luteus seeds.

A method for purification of tRNA nucleotidyltransferase from Lupinus luteus L. seeds on a preparative scale is presented. This involved ammonium sulfate fractionation and chromatography on DEAE-cellulose, hydroxylapatite, and QAE-Sephadex A-50. The final enzyme prepartion was apparently homogeneous and a 2000-fold purification was achieved. Data presented suggest the existence of only one form of tRNA nucleotidyltransferase in dry lupin seeds.

Plant tRNA nucleotidyltransferase : II. Some properties of the purified enzyme from Lupinus luteus seeds.

Purified lupine tRNA nucleotidyltransferase catalyzed only the incorporation of AMP and CMP into 3'-terminal-C-C-A sequences of tRNA as determined by terminal analysis of the reaction product. The incorporation of AMP and CMP was inhibited by their respective triphosphates to different degrees; UTP also showed an inhibitory effect. The pH optimum of the purified enzyme was found to be 9.5 in glycine buffer. The enzyme required magnesium or manganese ions for its activity.-SH reagents reversibly inhibited the action of the enzyme. Kinetic data, the different effects of ionic strength on the incorporation of AMP and CMP, and different rates of thermal inactivation for AMP and CMP incorporation in connection with chromatographic properties of the enzyme suggest the existence of only one form of tRNA nucleotidyltransferase with different catalytic sites for ATP and CTP.

[Reduction dynamics of S-S bonds in wheat gluten]. / Reduktionsdynamik der S-S-Bindungen im Weizenkleber

The new method of S-S bond determination was elaborated. It was based on the reduction of S-S bonds using 2-mercaptoethanol/ME/, the separation of the excess of ME using the Sephadex column and the application of ELLMAN's reagent for the determination of reduced SH groups. Using this method much higher contents of total S-S bonds, as well as of intermolecular ones could be observed, than by using Na2SO3 as a reducing agent. During the experiments on the reductivity of intermolecular S-S bonds in all investigated samples of gluten under the action of ME initially the increase of SH groups and then some steady state period could be noticed, in which no increase occurred, followed by further reduction. This means, that the one more type of S-S bonds, more accessible for the reducing agent of all may exist. It is suggested, that it can be the quaternary S-S bonds joining together separate molecules to form complexes able to disperse. As the observed "plateau" representing those bonds occurs at different level of the reduction percent and at the different time, after the reduction have been started, does the amount and strength of those bonds not influence the gluten quality.