共查询到20条相似文献,搜索用时 15 毫秒
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Summary Hemoglobins M and unstable hemoglobins cause clinical syndromes that are transmitted in autosomal dominant fashion. Pedigrees of 50 probands with de novo mutations producing unstable Hb disease or Hb M disease were compiled. Cases were ascertained (1) by screening the relevant literature published from 1950 through 1980 and (2) through personal communication. Additional pedigree data on several published cases were collected, and a depository containing all available information rekated to de novo Hb mutants was established. The 50 probands were born in 14 countries between 1922 and 1976. Paternity was tested in 36% of the cases, and no instance of false paternity was noted.The data were used to test for an association of advanced parental age with the appearance of de novo mutants. Paternal ages at the probands' births ranged from 20 to 50 years, with a mean of 32.7 years. Maternal ages ranged from 18 to 43 years, with a mean of 28.5 years. For each year and country (or, where necessary, for the nearest possible year and/or a demographically similar country), the cumulative frequency distributions of the ages of parents who had a child in that country and year were computed; the ages of each proband's father and mother were then expressed as percentiles on these distributions. The distribution of paternal age percentiles was shifted toward the upper end of the range, with 11 of the 50 paternal ages falling between the 90th and 100th percentiles. The distribution of maternal age percentiles was more complex, with one peak (10 of 50 ages) falling between the 30th and 40th percentiles and a second peak (10 of 50 ages), between the 90th and 100th percentiles. These distributions, though suggestive of an association of advanced parental age and the appearance of de novo mutations that cause unstable Hb disease or methemoglobinemic cyanosis, were not significantly different from those uniform distributions expected in the absence of a parental age effect. 相似文献
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Brittain T 《Journal of inorganic biochemistry》2005,99(1):120-129
The Root effect describes an extreme pH sensitivity expressed in the hemoglobins of certain fish, in which it plays a unique physiological role. This review describes our general understanding of the effect of protons on the oxygen binding properties of hemoglobin and the particular properties which characterize Root effect proteins. The development of our understanding of the molecular origins of this effect is outlined and the role played by our ever expanding knowledge of protein structure is highlighted. The present state of our knowledge is detailed. 相似文献
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SAHA A 《Biochimica et biophysica acta》1959,32(1):258-261
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K Winnefeld 《Folia haematologica (Leipzig, Germany : 1928)》1989,116(5):761-767
Haemoglobin is primarily responsible for the oxygen supply and a normal acid-base economy in mammals. An optimal loading of haemoglobin with oxygen in the lungs and a high desaturation in the periphery are ensured by a highly cooperative oxygen binding of 4 subunits as well as by different effectors--2,3 DPG, chloride, pH, temperature...-.A number of differently built-up haemoglobins will ensure a sufficient oxygen supply of individual ontogenetic stages of development in the human organism. 相似文献
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B Giardina F Arevalo M E Clementi L Ferrara A Di Luccia E Lendaro A Bellelli S G Condò 《European journal of biochemistry》1992,204(2):509-513
The ligand-binding properties of hemoglobins from two homozygote phenotypes (AA and BB) of water buffalo (Bubalus bubalis) have been characterized by equilibrium and kinetic techniques. In the case of the BB phenotype, the two constituent hemoglobins have been purified and separately analysed. Buffalo hemoglobins display the reduced sensitivity to organic phosphates characteristic of ruminant hemoglobins, their physiological effector probably being the chloride ion. In contrast to the other known hemoglobins from ruminants, all the hemoglobins from the water buffalo display a significant temperature sensitivity, the delta H for oxygen binding in the presence of physiological effectors approaching that of human hemoglobin (delta H = -30.5 kJ/mol O2). This discrepancy with the other ruminant hemoglobins (e.g. ox, delta H = -10.4 kJ/mol O2), whose primary structure is very similar to that of buffalo, hemoglobins might be correlated to the different habitat and phylogenetic history of the two subfamilies (Bos and Bubalus) of Bovidae. 相似文献
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Functional properties of carboxypeptidase-digested hemoglobins 总被引:4,自引:0,他引:4
J Bonaventura C Bonaventura M Brunori B Giardina E Antonini F Bossa J Wyman 《Journal of molecular biology》1974,82(4):499-511
Hemoglobin molecules after digestion with carboxypeptidase A or B show large differences in their ligand affinity, heme-heme interaction, Bohr effect and response to organic phosphates. Removal of β146 histidine and β145 tyrosine produces a molecule of high oxygen affinity, low Bohr effect and no heme-heme interaction. Removal of α141 arginine produces similar, but less drastic, changes. In both digestion products normal functional behavior may be partially restored by addition of inositol hexaphosphate. Doubly digested hemoglobins (carboxypeptidase A followed by B or vice versa) have properties similar to the initial digestion products but are no longer responsive to organic phosphates. The equilibrium and kinetic properties of these proteins are presented and are consistent with the idea that various conformations of the unliganded molecules may be in equilibrium. 相似文献
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Plants,humans and hemoglobins 总被引:4,自引:0,他引:4
New developments have forced a re-evaluation of our understanding of the structure and function of hemoglobins. Leghemoglobins regulate oxygen affinity through a mechanism different from that of myoglobin using a novel combination of heme pocket amino acids that lower the oxygen affinity. The hexacoordinate hemoglobins are characterized by intramolecular coordination of the ligand binding site at the heme iron, and were first identified in plants as the 'non-symbiotic plant hemoglobins'. They are now known to be present in animals and bacteria. Many of these proteins are upregulated in both plants and animals during hypoxia or similar stresses. Therefore, there might be a common physiological function for hexacoordinate hemoglobins in plants and animals. 相似文献