scholarly journals ENZYME ACTIVITIES IN CHICK EMBRYONIC CARTILAGE

1971 ◽  
Vol 49 (2) ◽  
pp. 459-467 ◽  
Author(s):  
C. Arsenis ◽  
R. Eisenstein ◽  
L. W. Soble ◽  
K. E. Kuettner
Keyword(s):  
Enzyme Activities ◽  
High Speed ◽  
Subcellular Fraction ◽  
Subcellular Fractionation ◽  
Enzymatic Activities ◽  
Sensitive Technique ◽  
Embryonic Cartilage ◽  
Microzone Electrophoresis ◽  
High Speed Supernatant ◽  
Supernatant Solution

Some characteristic enzymatic activities were determined in chick embryonic cartilage and compared with the analogous activities in bone and liver. Chondrocytes were isolated, broken by sonication, and subjected to subcellular fractionation to yield a nuclear pellet, the mitochondrial, lysosomal, and microsomal fractions, and the high speed supernatant solution. It was established that these fractions are characterized by enzymatic activities usually associated with similar fractions in other tissues, but with some quantitative differences. Lysozyme, a particulate-associated enzyme in other tissues, was not detected in any subcellular fraction even by the sensitive technique of microzone electrophoresis and is therefore considered to be primarily extracellular in cartilage.

Secretagogue-induced changes in subcellular Ca2+ distribution in isolated pancreatic acini

1981 ◽  
Vol 240 (2) ◽  
pp. G130-G140
Author(s):  
R. L. Dormer ◽  
J. A. Williams
Keyword(s):  
Atomic Absorption Spectrometry ◽  
High Speed ◽  
Microsomal Fraction ◽  
Absorption Spectrometry ◽  
Subcellular Fractionation ◽  
Differential Centrifugation ◽  
Zymogen Granules ◽  
Pancreatic Acini ◽  
Induced Changes ◽  
Stimulation Of

In a prior study, we demonstrated that pancreatic secretagogues increased both the uptake into and washout of 45Ca2+ from isolated mouse pancreatic acini. The net result of these processes was an initial fall in total acinar cell Ca2+ content. In the present study, we have employed subcellular fractionation of acini under conditions that minimized posthomogenization redistribution of Ca2+ in order to localize those organelles involved in intracellular Ca2+ fluxes. Homogenization and differential centrifugation of acini, preloaded with 45Ca2+ and subjected to a period of washout, showed that carbachol induced an increased loss of 45Ca2+ from all fractions isolated. The high-speed microsomal fraction lost 45Ca2+ to a greater extent than did whole acini; measurement of total Ca2+ by atomic absorption spectrometry showed a net loss of Ca2+ from this fraction. Purification of the lower-speed fractions indicated that carbachol increased 45Ca2+ exchange with both zymogen granules and mitochondria, but net Ca2+ levels in these organelles were unchanged. It was concluded that stimulation of pancreatic acini by carbachol results in the release of calcium from a microsomal compartment leading to a rise in cytoplasmic Ca2+, increased exchange with granule and mitochondrial Ca2+, and increased efflux of Ca2+ from the cell.

scholarly journals Detection of CMP-N-acetylneuraminic acid hydroxylase activity in fractionated mouse liver

1989 ◽  
Vol 263 (2) ◽  
pp. 355-363 ◽  
Author(s):  
L Shaw ◽  
R Schauer
Keyword(s):  
Submandibular Gland ◽  
Mouse Liver ◽  
High Speed ◽  
Metal Salts ◽  
Supernatant Fraction ◽  
Inhibitory Influence ◽  
Hydroxylase Activity ◽  
Acetylneuraminic Acid ◽  
Liver Homogenates ◽  
High Speed Supernatant

The finding that N-glycoloylneuraminic acid (Neu5Gc) in pig submandibular gland is synthesized by hydroxylation of the sugar nucleotide CMP-Neu5Ac [Shaw & Schauer (1988) Biol. Chem. Hoppe-Seyler 369, 477-486] prompted us to investigate further the biosynthesis of this sialic acid in mouse liver. Free [14C]Neu5Ac, CMP-[14C]Neu5Ac and [14C]Neu5Ac glycosidically bound by Gal alpha 2-3- and Gal alpha 2-6-GlcNAc beta 1-4 linkages to fetuin were employed as potential substrates in experiments with fractionated mouse liver homogenates. The only substrate to be hydroxylated was the CMP-Neu5Ac glycoside. The product of the reaction was identified by chemical and enzymic methods as CMP-Neu5Gc. All of the CMP-Neu5Ac hydroxylase activity was detected in the high-speed supernatant fraction. The hydroxylase required a reduced nicotinamide nucleotide [NAD(P)H] coenzyme and molecular oxygen for activity. Furthermore, the activity of this enzyme was enhanced by exogenously added Fe2+ or Fe3+ ions, all other metal salts tested having a negligible or inhibitory influence. This hydroxylase is therefore tentatively classified as a monooxygenase. The cofactor requirement and CMP-Neu5Ac substrate specificity are identical to those of the enzyme in high-speed supernatants of pig submandibular gland, suggesting that this is a common route of Neu5Gc biosynthesis. The relevance of these results to the regulation of Neu5Gc expression in sialoglycoconjugates is discussed.

scholarly journals Discrete primary locations of a tyrosine-protein kinase and of three proteins that contain phosphotyrosine in virally transformed chick fibroblasts.

1982 ◽  
Vol 94 (2) ◽  
pp. 287-296 ◽  
Author(s):  
J A Cooper ◽  
T Hunter
Keyword(s):  
Protein Kinase ◽  
High Speed ◽  
Divalent Cations ◽  
Rous Sarcoma ◽  
Nonionic Detergent ◽  
Primary Location ◽  
Hypotonic Buffer ◽  
Tyrosine Protein Kinase ◽  
Sarcoma Virus ◽  
High Speed Supernatant

We have studied the localization of three abundant cellular proteins which are substrates for tyrosine protein kinases in virally transformed chicken embryo fibroblasts. The primary location of each substrate is unaltered by transformation with Rous sarcoma virus (RSV). The tyrosine-phosphorylated species is localized with the nonphosphorylated species. Two of the proteins, of about 46,000 and 28,000 daltons, have a similar location. They are present in the high speed supernatant of cells homogenized in hypotonic buffer, and are soluble in nonionic detergent. The third protein, of about 39,000 daltons, is particulate when cells are homogenized in hypotonic buffer containing divalent cations, but approximately 30% is free in the high-speed supernatant when divalent cations are absent. This protein appears to be associated with the detergent-insoluble matrix when adherent cells are gently lysed in nonionic detergent in situ, but is soluble when the same cells are extracted with nonionic detergent in suspension. This suggests that one of the proteins are tightly associated with detergent-insoluble cytoskeletal structures, unlike the RSV transforming protein itself, which is the main tyrosine protein kinase known to be active in RSV-transformed cells.

scholarly journals Novel prostaglandin dehydrogenase in rat skin

1983 ◽  
Vol 212 (1) ◽  
pp. 129-134 ◽  
Author(s):  
N Fincham ◽  
R Camp
Keyword(s):  
High Speed ◽  
Reaction Rates ◽  
Inhibitory Effects ◽  
Rat Skin ◽  
Prostaglandin F2 Alpha ◽  
Prostaglandin Dehydrogenase ◽  
The Mean ◽  
Inhibition Studies ◽  
Kinetics Of ◽  
High Speed Supernatant

Present evidence suggests that skin is an important organ of prostaglandin metabolism. To clarify its role, the basic kinetics of 15-hydroxyprostaglandin dehydrogenase (PGDH) from rat skin were investigated with either NAD+ of NADP+ as co-substrate. Prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) were used as substrates and preliminary studies were made of the inhibitory effects of the reduced co-substrates NADH and NADPH. A radiochemical assay was used in which [3H]PGF2 alpha or [14C]PGE2 were incubated with high-speed supernatant of rat skin homogenates. The substrate and products were then extracted by solvent partition, separated by t.l.c. and quantified by liquid-scintillation counting. At linear reaction rates and at an NAD+ concentration of 10 mM the mean apparent Km for PGF2 alpha was 24 microM with a mean apparent Vmax. of 9.8 nmol/s per litre of reaction mixture. For PGE2 the mean apparent Km was 8 microM, with a mean apparent Vmax, of 2.7 nmol/s per litre of reaction mixture. With NADP+ as a co-substrate at a concentration of 5 mM a mean apparent Km of 23 microM was obtained for PGF2 alpha with a mean apparent Vmax. of 5.2 nmol/s per litre. For PGE2 values of 7.5 microM and 3.0 nmol/s per litre were obtained respectively. These results show that skin contains NAD+- and NADP+-dependent PGDH. An important finding was that the NADP+-linked enzyme gave Km values for PGE2 that were considerably lower than those reported for NADP+-linked PGDH from other tissues. Furthermore, preliminary inhibition studies with the NAD+-linked PGDH system indicate that this enzyme is not only inhibited by NADH, but also by NADPH, a property not previously reported for NAD+-linked PGDH derived from other tissues.

scholarly journals Lipogenesis in liver, lung and adipose tissue of rats fed with oleoylanilide

1983 ◽  
Vol 212 (2) ◽  
pp. 339-344 ◽  
Author(s):  
C Casals ◽  
P Garcia-Barreno ◽  
A M Municio
Keyword(s):  
Adipose Tissue ◽  
Enzyme Activities ◽  
Liver Toxicity ◽  
Subcellular Fractionation ◽  
Major Effect ◽  
Considerable Extent ◽  
Lymphatic Gland ◽  
Target Organs ◽  
Main Target ◽  
Organ Response

Oleoylanilide was administered orally to groups of rats according to different patterns. Subcellular fractionation of liver, lung and adipose tissue was then carried out in order to study the main enzyme activities involved in the lipogenesis. The observed findings indicate that adipose tissue and lung are the main target organs for the anilide, adipose tissue being involved in a general decrease of the enzyme activities, whereas transacylation reaction exhibits the most marked depletion of all the enzyme activities in the lung. The enzyme activities in liver were not markedly affected by this oral administration, although some data support the existence of a latent liver toxicity. These data suggest that oleoylanilide has the capacity to alter lipid metabolism of lung and adipose tissue to a considerable extent, whereas no major effect was produced in the liver. This different organ response could be related to the lymphatic gland via absorption of the substance.

‘Binding’ of [14C]phenol to rat liver high-speed supernatant

1980 ◽  
Vol 8 (1) ◽  
pp. 117-118
Author(s):  
H. PAUL A. ILLING ◽  
ESTHER S. A. HOUSE
Keyword(s):  
Rat Liver ◽  
High Speed ◽  
High Speed Supernatant
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