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R Crea

Publications and source records attributed to R Crea.

27 records · Page 2Linked to original sources
PubMed1980

Synthesis of oligonucleotides on cellulose by a phosphotriester method.

The synthesis of oligothymidilic acids, (dT)m (where m = 4, 7, 10, 13, 16, 19, 22, and 25), was carried out using a solid phase approach in combination with the modified phosphotriester methodology developed in solution. Cellulose was used as the solid support after its functionalization with a specially featured dinucleoside diphosphate, 5'-0-p-chlorophenylphospho-2'(3')-0-acetyluridilyl-[2'(3')-3']-5'-0-dimethoxytritylthymidine p-chlorophenylester. The fully protected trideoxynucleoside triphosphate containing only thymidine was repeatedly used to elongate the oligonucleotide chain in the 3'-5' direction. Individual coupling yields ranged from 45% to 75%. The total time needed to prepare (dT)25 was four days. Similarly, the tridecanucleotide d(AGAAGGTACTTTT) was synthesized in good yield. The results show that this approach can be used for a fast and economic way to synthesize oligodeoxynucleotides.

Cellulose↗
PubMed1980

Synthesis of oligonucleotides on cellulose. Part II: Design and synthetic strategy to the synthesis of 22 oligodeoxynucleotides coding for gastric inhibitory polypeptide (GIP).

A solid-phase approach using trinucleotide building blocks and functionalized cellulose as solid support was used to synthesize the 22 oligodeoxynucleotides that constitute a totally synthetic gene coding for a 43 amino acid peptide. Gastric inhibitory Polypeptide. The overall strategy used for the design and synthesis of the oligomers is described.

Amino Acid Sequence↗
PubMed1979

Direct expression in Escherichia coli of a DNA sequence coding for human growth hormone.

DNA coding for human growth hormone was constructed by using chemically synthesised DNA in conjunction with enzymatically prepared cDNA. This 'hybrid' gene was expressed in Escherichia coli under the control of the lac promoter. A polypeptide was produced having the size and immunological properties characteristic of mature human growth hormone.

Base Sequence↗
PubMed1979

Expression in Escherichia coli of chemically synthesized genes for human insulin.

Synthetic genes for human insulin A and B chains were cloned separately in plasmid pBR322. The cloned synthetic genes were then fused to an Escherichia coli beta-galactosidase gene to provide efficient transcription and translation and a stable precursor protein. The insulin peptides were cleaved from beta-galactosidase, detected by radioimmunoassay, and purified. Complete purification of the A chain and partial purification of the B chain were achieved. These products were mixed, reduced, and reoxidized. The presence of insulin was detected by radioimmunoassay.

Amino Acids↗
PubMed1978

Chemical synthesis of genes for human insulin.

A rapid chemical procedure has been developed and used for the synthesis of 29 oligodeoxyribonucleotides to build synthetic genes for human insulin. The gene for insulin B chain, 104 base pairs, and the one for A chain, 77 base pairs, were designed from the amino acid sequence of human polypeptides. They bear single-stranded cohesive termini for the EcoRI and BamHI restriction endonucleases and are designed to be inserted separately into a pBR322 plasmid. The synthetic fragments, deca- to pentadecanucleotides, were synthesized by a block phosphotriester method with trinucleotides as building blocks. Final purification was by high-performance liquid chromatography. All 29 oligonucleotides were pure and had the correct sequences.

DNA↗
PubMed1977

Expression in Escherichia coli of a chemically synthesized gene for the hormone somatostatin.

A gene for somatostatin, a mammalian peptide (14 amino acid residues) hormone, was synthesized by chemical methods. This gene was fused to the Escherichia coli beta-galactosidase gene on the plasmid pBR322. Transformation of E. coli with the chimeric plasmid DNA led to the synthesis of a polypeptide including the sequence of amino acids corresponding to somatostatin. In vitro, active somatostatin was specifically cleaved from the large chimeric protein by treatment with cyanogen bromide. This represents the first synthesis of a functional polypeptide product from a gene of chemically synthesized origin.

Base Sequence↗