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M H Hu

Publications and source records attributed to M H Hu.

23 records · Page 2Linked to original sources
PubMed1983

Total synthesis of yeast alanine transfer ribonucleic acid.

By a combination of chemical and enzymatic methods, small oligonucleotides with lengths varying from 2 to 8 nucleotides were synthesized from mononucleotides. The small oligonucleotides were then ligated with T4 RNA ligase into six large oligonucleotides (9 to 19 nucleotides long) which were further ligated to form two half molecules with 35 and 41 nucleotides respectively. Finally, the two synthetic half molecules were annealed and ligated to obtain the whole molecule of yeast alanine tRNA (tRNAAlay). Prior to this, two semi-syntheses were performed, i.e. ligation of the synthetic 5'-half molecule with the natural 3'-half molecule and that of the natural 5'-half molecule with the synthetic 3'-half molecule. Both the semi-synthetic tRNAAlay and the synthetic tRNAAlay occupy the same position as the natural tRNAAlay after electrophoresis on a 20% polyacrylamide gel. They have the same chemical composition (containing 9 modified nucleotides of 7 different species) and structure as the natural tRNAAlay and are biologically active, i.e. accepting and transferring alanine into proteins in a cell-free protein synthesizing system, the accepting activity of the synthetic product is 52-66% of that of the natural tRNAAlay and 91-106% of that of the reconstituted product of the two natural half molecules. The incorporation activity of alanine into proteins of the synthetic 3H-alanine tRNAAlay is 63%, corresponding to 91% of that of the natural tRNAAlay and 115% of that of the reconstituted product of the two natural half molecules. To the best of our knowledge, this is the first time that a natural RNA with biological activity is synthesized.

Base Sequence↗
PubMed1983

Synthesis of the 3'-half molecule of yeast alanine tRNA.

This paper deals with the synthesis of the 3'-half molecule of yeast alanine transfer RNA (tRNAAlay) by ligation with T4 RNA ligase of three component oligonucleotide fragments corresponding to nucleotides 36-45(I), 46-57(II) and 58-76(III) in succession extending from the 3'-end to the 5'-end. First, in a ratio of acceptor to donor at 1.5 to 1, we adopted a method of three successive reactions, namely, the 5'-phosphorylation of the nonadecamer (III), ligation with the dodecamer (II) and the 5'-phosphorylation of the ligation product formed; with one isolation step and obtained the 5'-phosphorylated 31mer(46-76) (IV) in an overall yield of 70%. Then the 31mer(IV) as a donor was ligated with 3 times of decamer (I) to form the 41mer(36-76) (V), the 3'-half molecule of tRNAAlay. The yield was 67%. After 5'-phosphorylation, (V) was ligated with the natural 5'-half molecule to form the semi-synthetic tRNAAlay, which was biologically active, i.e. accepting and transferring (3H)-alanine into proteins.

Base Sequence↗
PubMed1982

Roentgenologic manifestations of pulmonary metastases in choriocarcinoma and invasive mole.

From 1949 to 1975, a total of 3,915 chest films were taken for 429 cases of choriocarcinoma and 441 cases of invasive mole. The incidences of pulmonary metastases were 85.1% and 65.0%, respectively. The various forms of pulmonary metastases were studied and correlated with clinical symptoms and pathologic changes. In order to follow up the progression or regression of the various forms, serial chest films were taken at intervals of 10 to 14 days in 27 cases. In eight cases postmortem pulmonary arteriograms were obtained on the autopsied lung specimens for the study of vascular changes of metastatic lesions. Pathologic examinations and pulmonary arteriography were also done on the surgically resected lung specimens. As a result of this study, a relative comprehensive knowledge about the nature and development of the various forms of metastatic shadows has been deduced. It is rational to say that the various forms seen on the chest films represent only the various evolutionary changes of the same lesion.

Angiography↗