Search PubMed⌕ Search

Biomedical subjects

A L TAPPEL

Publications and source records attributed to A L TAPPEL.

At least 19 recordsLinked to original sources
PubMed1965

RAT-KIDNEY LYSOSOMES: ISOLATION AND PROPERTIES.

1. The activities of lysosomal enzymes in the cortexes and medullas and the principal subcellular fractions of rat kidney were measured. 2. A method is described for the isolation of rat-kidney lysosomes and a detailed analysis of the enzymic composition of the lysosomes is reported. Enzyme analysis of the other principal subcellular fractions is included for comparison. 3. Studies of the distribution of alpha-glucosidase showed that the lysosomal fraction contained only 10% of the total enzyme activity. The microsomal fraction contained most of the particulate alpha-glucosidase. Lysozyme was concentrated mainly in the lysosomal fraction with only small amounts present in the microsomal fraction. Lysosomal alpha-glucosidase had optimum pH5 whereas the microsomal form had optimum pH6. Both lysosomal and microsomal lysozyme had optimum pH6.2. 4. The stability of lysosomal suspensions was studied. Incubation at 37 degrees and pH7 resulted in first an increased availability of enzymes without parallel release of enzyme. This was followed by a second stage during which the availability of enzymes was closely related to the release of enzymes. These changes were closely paralleled by changes in light-scattering properties of lysosomes. 5. The latent nature of the alpha-glucosidase and lysozyme of intact kidney lysosomes was demonstrated by their graded and parallel release with other typical lysosomal enzymes. 6. Isolated lysosomes were unstable at pH values lower than 5, most stable at pH6-7 and less stable at pH 8-9. Lysosomes were not disrupted when the osmolarity of the suspending medium was decreased from 0.6m to 0.25m. 7. The discussion compares the properties and composition of kidney lysosomes, liver lysosomes and the granules of macrophages. 8. The possible origin of the lysozyme in kidney lysosomes by reabsorption of the lysozyme in blood is discussed.

Acid Phosphatase↗
PubMed1964

SELENOAMINO ACIDS: DECREASE OF RADIATION DAMAGE TO AMINO ACIDS AND PROTEINS.

Selenomethionine and selenocystine protect amino acid and protein systems from radiation damage. Selenoamino acids are more powerful protectors than the analogous sulfur amino acids and other known -SH protectors. Free-radical scavenger and repair mechanisms by which selenoamino acids react with induced free radicals may be the key reactions in the biological function of logical function of selenium.

Alanine↗
PubMed1964

LYSOSOMAL ENZYMES OF RAT INTESTINAL MUCOSA.

Six intracellular hydrolases known to be associated with lysosomes in rat liver were found in rat intestinal mucosa. The extent to which they were particulate-bound and the degree of enzyme release when the particulate fractions were suspended in hypotonic media followed the same pattern in both mucosa and liver. The specific activities of the mucosa enzymes were either comparable to or slightly smaller than those of the liver enzymes. These results suggest that the mucosa hydrolases belong to lysosome-like particles. However, differential fractionation of the mucosa indicated that the particles from the mucosa sediment at lower centrifugal forces than do those from the liver and are more heterogeneous in size, bearing a closer resemblance to kidney lysosomes. Possible physiological functions of particulate-bound digestive enzymes in intestinal mucosa are discussed.

Acid Phosphatase↗