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71.
Novel mechanism for high-altitude adaptation in hemoglobin of the Andean frog Telmatobius peruvianus
Weber RE Ostojic H Fago A Dewilde S Van Hauwaert ML Moens L Monge C 《American journal of physiology. Regulatory, integrative and comparative physiology》2002,283(5):R1052-R1060
In contrast to birds and mammals, no information appears to be available on the molecular adaptations for O(2) transport in high-altitude ectothermic vertebrates. We investigated Hb of the aquatic Andean frog Telmatobius peruvianus from 3,800-m altitude as regards isoform differentiation, sensitivity to allosteric cofactors, and primary structures of the alpha- and beta-chains, and we carried out comparative O(2)-binding measurements on Hb of lowland Xenopus laevis. The three T. peruvianus isoHbs show similar functional properties. The high O(2) affinity of the major component results from an almost complete obliteration of chloride sensitivity, which correlates with two alpha-chain modifications: blockage of the NH(2)-terminal residues and replacement by nonpolar Ala of polar residues Ser and Thr found at position alpha131(H14) in human and X. leavis Hbs, respectively. The data indicate adaptive significance of alpha-chain chloride-binding sites in amphibians, in contrast to human Hb where chloride appears mainly to bind in the cavity between the beta-chains. The findings are discussed in relation to other strategies for high-altitude adaptations in amphibians. 相似文献
72.
S. Karsten Elena Voskoboeva Svetlana Tishkanina U. Pettersson Xcenia Krasnopolskaja Marie-Louise Bondeson 《Human genetics》1998,103(6):732-735
We present a mutational analysis of the iduronate-2-sulfatase (IDS) gene of 36 Russian patients with Hunter syndrome. Among
29 mutant alleles, there were 19 missense mutations, 1 nonsense mutation, 6 mutations affecting splice sites, and 3 major
structural alterations resulting in deletions. Of the 25 different mutations, 15 are novel and unique. Most of the missense
mutations result in intermediate or severe phenotypes.
Received: 1 June 1998 / Accepted: 27 July 1998 相似文献
73.
An arginine carboxypeptidase was isolated from the cell walls ofStreptococcus mitis ATCC 15909 by mutanolysin extraction of the walls. The enzyme was purified 32-fold by gel filtration on Sephacryl S-300, affinity chromatography on Arginine-Sepharose 4B and by rechromatography on Sephacryl S-300. The molecular mass of the enzyme was calculated to 122 kDa by gel filtration. The enzyme released arginine from the carboxy terminal of hippurylarginine and, at a low rate, lysine from furylacryloylalanyl-lysine and hippuryl-lysine. The carboxypeptidase seemed firmly bound to the cell wall because SDS treatment of the walls did not release measurable amounts of activity. 相似文献
74.
75.
Marie-Louise Bouillant André Besset Jean Favre-Bonvin Jean Chopin 《Phytochemistry》1978,17(3):527-533
Permethylated O-glycosyl-C-glycosylflavones give well defined MS including an important molecular peak. Permethyl 6-C-glycosylflavones O-glycosylated on a phenolic hydroxyl group are easily distinguished from the isomeric permethyl 6-C-diholosylflavones. In both types, the position of the O-glycosidic bond can be deduced from the MS, eventually after acid hydrolysis. 2″-O-glycosyl-6-C-glycosylflavones can be differentiated from their 8-C isomers. 相似文献
76.
Marie-Aleth Dubois Anne Zoll Marie-Louise Bouillant Jean Chopin 《Phytochemistry》1982,21(5):1141-1143
Three C-glycosylflavones isolated from Cerastium arvense have been identified as 6-C-xylosyl-apigenin (cerarvensin), its 7-O-glucoside and isovitexin 7,2″-di-O-glucoside. 相似文献
77.
Combe E Pirman T Stekar J Houlier ML Mirand PP 《The Journal of nutritional biochemistry》2004,15(1):12-17
The aim of this work was to test the hypothesis that the trophic effect of lentil feeding on large intestine results from a stimulation of protein synthesis and to determine whether it interferes with protein metabolism in other splanchnic or peripheral organs. Two groups of growing Sprague Dawley male rats were pair-fed iso-caloric iso-nitrogenous balanced diets containing either cooked lentils (Lens esculenta puyensis) or casein as unique protein source. Protein synthesis rates were measured in vivo, in large intestine, liver and gastrocnemius at the postprandial state. In large intestine, protein and ribonucleic acid contents were higher in the lentil-fed group than in the control group, and the amount of proteins synthesized was also higher (+57%). By contrast, liver protein and ribonucleic acid contents as well as protein synthesis rates were significantly lower in the lentil-fed group than in the control group. In the gastrocnemius muscle protein and ribonucleic acid contents were significantly lower and the amount of protein synthesized was also lower (-18%) in the lentil fed group than in the control group. This study suggests that stimulation of protein synthesis in the large intestine is compensated for by a decrease in liver and muscle. 相似文献
78.
Hartoft-Nielsen ML Lange M Rasmussen AK Scherer S Zimmermann-Belsing T Feldt-Rasmussen U 《Hormone research》2004,61(2):53-57
OBJECTIVES: To evaluate the value of the thyrotropin-releasing hormone (TRH) stimulation test in the diagnostic work-up of the thyroid function in patients with pituitary pathology. METHODS: To compare the thyrotropin (TSH) response and the absolute and fold changes after TRH administration in 35 patients with pituitary pathology and 26 normal subjects. RESULTS: Nine of the patients and 2 of the normal subjects had a pathological response. No difference in the thyrotropic response to TRH was found either for the actual values, or for the absolute or fold changes of TSH between the groups. CONCLUSION: The role of the TRH test in the evaluation of thyroid function in patients with pituitary pathology is modest. The best variables for evaluation of the presence of central hypothyroidism are still a free thyroxine estimate combined with an inappropriately low TSH. 相似文献
79.
A number of serine, cysteine, metallo- and acid proteases were evaluated for their ability to proteolytically cleave the serine protease inhibitor trappin-2, also known as pre-elafin, and to release elafin from its precursor. None of the metalloproteases or acid proteases examined cleaved trappin-2, while serine and cysteine proteases preferentially cleaved trappin-2 within its non-inhibitory N-terminal moiety. Cathepsin L, cathepsin K, plasmin, trypsin and tryptase were able to release elafin by cleaving the Lys 38 -Ala 39 peptide bond in trappin-2. However, purified tryptase appeared to be efficient at releasing elafin. Incubation of trappin-2 with purified mast cells first challenged with anti-immunoglobulin E or calcium ionophore A23187 resulted in the rapid generation of elafin. This proteolytic release of elafin from trappin-2 was inhibited in the presence of a tryptase inhibitor, suggesting that this mast cell enzyme was involved in the process. Finally, ex vivo incubation of trappin-2 with sputum from cystic fibrosis patients indicated the production of a proteolytic immunoreactive fragment with the same mass as that of native elafin. This cleavage did not occur when preincubating the sputum with polyclonal antibodies directed against tryptase. Taken together, these findings indicate that tryptase could likely be involved in the maturation of trappin-2 into elafin under physiological conditions. 相似文献
80.
Paul J. Benke Joseph C. Parker Jr. Marie-Louise Lubs Judith Benkendorf Anne E. Feuer 《Human genetics》1982,61(1):52-59
Summary Three subpopulations of the Hadza were examined for the following antigens and proteins including enzymes A1ABH, MNS Henshaw, C c CW D Du E e V Ce, Lua, KJsa, Fy1 Fy2, Jka Jkb, Dia, Wra, haemoglobin, haptoglobin, transferrin, acid phosphatase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase, adenylate kinase, lactate dehydrogenase, and malate dehydrogenase. The results are discussed in relation to other African populations including the Sandawe, Nyaturu, Pygmies, San, and Khoikhoi. 相似文献