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Oxalyl-CPG: a labile support for synthesis of sensitive oligonucleotide derivatives. 总被引:11,自引:10,他引:1 下载免费PDF全文
A procedure is described for linking nucleosides covalently to controlled pore glass or cross-linked polystyrene supports by means of an oxalyl anchor. Though stable to triethylamine and diisopropylamine, the nucleoside-oxalyl link can be cleaved within a few minutes at room temperature with ammonium hydroxide in methanol. This new anchor can be used in automated synthesis of conventional oligonucleotides. The primary value, however, is that it enables one to employ solid support methodology to synthesize a variety of base-sensitive oligonucleotide derivatives, as illustrated here by synthesis of oligomers with base protecting groups intact and with methyl phosphotriester groups at the internucleoside links. 相似文献
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Osteogenesis imperfecta due to recurrent point mutations at CpG dinucleotides in the COL1A1 gene of type I collagen 总被引:7,自引:3,他引:4
Charles J. Pruchno Daniel H. Cohn Gillian A. Wallis Marcia C. Willing Barbra J. Starman Xiaoming Zhang Peter H. Byers 《Human genetics》1991,87(1):33-40
Summary Most individuals with osteogenesis imperfecta (OI) are heterozygous for dominant mutations in one of the genes that encode the chains of type I collagen. Each of the more than 30 mutations characterized to date has been unique to the affected member (s) of the family. We have determined that two individuals with a progressive deforming variety of OI, OI type III, have the same new dominant mutation [1(I)gly154 to arg] and that two unrelated infants with perinatal lethal OI, OI type II, share a second new dominant muation [1(I)gly1003 to ser]. These mutations occurred at CpG dinucleotides, in a manner consistent with deamination of a methylated cytosine residue, and raise the possibility that CpG dinucleotides are common sites of recurrent mutations in collagen genes. Further, these findings confirm that the OI type-III phenotype, previously thought to be inherited in an autosomal recessive manner, can result from new dominant mutations in the COL1A1 gene of type-I collagen. 相似文献
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The present study was intended to examine the structure of the rat Leydig cell gonadotropin receptor. Leydig cell suspensions were prepared by either collagenase digestion or mechanical disruption of the testes. The cells were incubated with 125I-human chorionic gonadotropin (hCG) following which the bound 125I-hCG was covalently cross-linked to the cell surface receptor using a cleavable (dithiobis(succinimidyl propionate] and a noncleavable (disuccinimidyl suberate) cross-linking reagent. The extracted cross-linked membrane proteins were resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions and subjected to autoradiographic analysis. Under nonreducing conditions, three radiolabeled bands, in addition to intact hCG and its alpha-subunit, were detected with apparent molecular weights of 184,000, 136,000, and 103,000. However, under reducing conditions, three radiolabeled bands migrated on the gel corresponding to molecular weights of 144,000, 106,000, and 75,000. The binding of 125I-hCG to the receptor was inhibited by hCG and luteinizing hormone, but not by a number of other peptides or proteins. The radiolabeled bands were not detectable in hCG down-regulated Leydig cells. Furthermore, a similar autoradiographic pattern of 125I-hCG-linked complexes was seen when the 125I-linked receptor complex was subjected to immunoprecipitation with anti-hCG antibodies followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In addition, evidence was obtained indicating that these three labeled bands were derived from the same molecular species. The data suggests that the hCG receptor in Leydig cell is probably an oligomeric complex with a molecular weight of about 250,000, which is composed of three polypeptide chains of molecular weights 121,000, 83,000, and 52,000 held together through noncovalent forces. Additionally, collagenase treatment of Leydig cells does not appear to alter the autoradiographic pattern of the 125I-hCG-linked receptor. 相似文献
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低温对大鼠骨骼肌能量代谢的影响——Ⅰ.高能磷酸化合物含量的变化 总被引:1,自引:1,他引:0
本实验选择对低温比较敏感的骨骼肌组织作为实验对象。将19只大鼠随机分成3组,其右后肢经冷冻处理使组织温度分别达 5℃、0℃及-5℃,于复温后不同时间测定骨骼肌中四种高能磷酸化合物AMP,ADP、ATP及CP的含量。结果表明,大鼠骨骼肌组织中高能磷酸化合物含量随冷冻时组织最低温度的下降而不同程度的减少,并且具有明显的时相过程。复温后即刻至4小时下降迅速,4~12小时三组值较为接近,其后随时间延长而明显分离。 5℃组恢复得早而且明显,0℃组恢复程度次于 5℃组,-5℃组含量下降最明显而且几乎不恢复。提示:低温使骨骼肌组织能量的产生和贮存过程受到影响。 相似文献
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