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A titrimetric method for the determination of molecular weight of small polynucleotides.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Al-Khalidi, U. Chernigoy, F. A. Kerr, Stanley E. |
| Copyright Year | 1957 |
| Abstract | The determination of the molecular weight of nucleic acids by physical methods has been criticized in view of the uncertain degree of aggregation which would result in high values (1). The effect of aggregation on the value obtained for the molecular weight of synthetic ribose polynucleotide by ultracentrifugation is clearly demonstrated in the studies of Ochoa on pure and mixed polymers and mixtures of these (2). If the molecular weights obtained by physical methods were to represent “chemical” molecular weights, then the postulate of branching through triester phosphate (3) would seem to be inevitable in view of the high values found for end groups in various samples by titration and by enzymatic methods. Brown, Magrath, and Todd, working with model phosphotriesters, found this grouping very unstable in aqueous solution and concluded that its presence in ribonucleic acid (RNA) was unlikely (4). A “chemical” method for the determination of the molecular weight of RNA samples which is not affected by physical aggregation and which does not presuppose the absence of triester phosphate linkages is therefore desirable. In this paper we propose such a method through titration of total phosphate groups. An examination of the various molecular structures proposed for RNA (see Fig. 1) reveals the fact that for each possible structure the number of titratable phosphoryl groups (P(OH)) . is one more than the total number of phosphorus atoms (P). Hence the number of nucleotides per molecule is equal to |
| File Format | PDF HTM / HTML |
| PubMed reference number | 13475334 |
| Journal | Medline |
| Volume Number | 228 |
| Issue Number | 1 |
| Alternate Webpage(s) | http://www.jbc.org/content/228/1/487.full.pdf |
| Journal | The Journal of biological chemistry |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
