Ribonuclease synthesis

Solid phase peptide synthesis does not solve all purification problems however Even if every coupling step m the ribonuclease synthesis proceeded in 99% yield the product would be contaminated with many different peptides containing 123 ammo acids 122 ammo acids and so on Thus Memfield and Gutte s six weeks of synthesis was fol lowed by four months spent m purifying the final product The technique has since been refined to the point that yields at the 99% level and greater are achieved with current instrumentation and thousands of peptides and peptide analogs have been prepared by the solid phase method... 

Commercially available computer-automated peptide synthesizers allow synthesis of a polypeptide in a time of about one hour or less per amino acid unit. The ribonuclease synthesis takes about one week or less. 

In the second phase of these investigations on protein synthesis, an attempt was made to study the process in vitro. At first, intact cells had to be used. Amino acid incorporation was studied in liver slices amylase, lipase, and ribonuclease synthesis was investigated in slices of pigeon pancreas and the incorporation of glycine into reticulocyte hemoglobin was measured. The first of the above systems was exploited with exceptional success in Zamecnik s laboratory [138]. 

K. Ulbrich, J. Strohalm, D. Plocova, D. Oupicky, V. ubr, J. Soucek, P. Pouckovd and J. Matousek, Poly[N-(2-hydroxypropyl)-methacrylamide] conjugates of bovine seminal ribonuclease. Synthesis, physicochemical, and preliminary biological evaluation, J. Bioact. Compat. Polym., 15, 4-26 (2000). 

Ribonuclease synthesis by isolated aleurone layers is enhanced only little by applied GA, although, like acid phosphatase, its release is massively stimulated (Fig. 7.7A). This release occurs considerably later than that of a-amylase. 

Memfield successfully automated all the steps m solid phase peptide synthesis and computer controlled equipment is now commercially available to perform this synthesis Using an early version of his peptide synthesizer m collaboration with coworker Bemd Gutte Memfield reported the synthesis of the enzyme ribonuclease m 1969 It took them only SIX weeks to perform the 369 reactions and 11 391 steps necessary to assemble the sequence of 124 ammo acids of ribonuclease... 

Synthesis of oxorhenium(V) and oxotechnetium(V) complexes as inhibitors of ribonucleases and for generation of catalytic antibodies 97SL537. 

Drought also has a profound effect on protein synthesis. In many plant tissues, a reduced water potential causes a reduction of total protein synthesis and a rapid dissociation of polyribosomes. The latter has been shown not to be the consequence of increase in ribonuclease activity (Hsiao, 1973 Dhindsa Bewley, 1976). For a specific protein, Jacobsen, Hanson Chandler (1986) have shown in barley leaves that water stress enhances the synthesis of one of the a-amylase isozymes. Using a cDNA probe they found that water-stressed leaves contained much more a-amylase mRNA than unstressed plants. 

After the virus has attached to CD4 and chemokine receptors, another viral glycoprotein (gp41) assists with viral fusion to the cell and internalization of the viral contents. The viral contents include single-stranded RNA, an RNA-dependent DNA polymerase (also known as reverse transcriptase), and other enzymes. Using the single-stranded viral RNA as a template, reverse transcriptase synthesizes a complementary strand of DNA. The single-stranded viral RNA is removed from the newly formed DNA strand by ribonuclease H, and reverse transcriptase completes the synthesis of double-stranded DNA. The... 

After synthesis, the mRNA exits the nucleus through a nuclear pore and proceeds to the ribosome for translation into protein. Competing with export and translation is the process of message degradation by cellular ribonucleases. The competition between degradation and translation provides another mechanism to regulate the levels of individual messages. 

H Romovacek, SR Dowd, K Kawasaki, N Nishi, K Hofmann. Studies on polypeptides. 54. The synthesis of a peptide corresponding to positions 24-104 of the peptide chain of ribonuclease I, . J Am Chem Soc 101, 6081, 1979. 

N Fujii, H Yajima. Total synthesis of bovine pancreatic ribonuclease A. Parts 1 to 6. J Chem Soc Perkin Trans 1 789, 1981. 

These three compounds exert many similar effects in nucleotide metabolism of chicks and rats [167]. They cause an increase of the liver RNA content and of the nucleotide content of the acid-soluble fraction in chicks [168], as well as an increase in rate of turnover of these polynucleotide structures [169,170]. Further experiments in chicks indicate that orotic acid, vitamin B12 and methionine exert a certain action on the activity of liver deoxyribonuclease, but have no effect on ribonuclease. Their effect is believed to be on the biosynthetic process rather than on catabolism [171]. Both orotic acid and vitamin Bu increase the levels of dihydrofolate reductase (EC 1.5.1.4), formyltetrahydrofolate synthetase and serine hydroxymethyl transferase in the chicken liver when added in diet. It is believed that orotic acid may act directly on the enzymes involved in the synthesis and interconversion of one-carbon folic acid derivatives [172]. The protein incorporation of serine, but not of leucine or methionine, is increased in the presence of either orotic acid or vitamin B12 [173]. In addition, these two compounds also exert a similar effect on the increased formate incorporation into the RNA of liver cell fractions in chicks [174—176]. It is therefore postulated that there may be a common role of orotic acid and vitamin Bj2 at the level of the transcription process in m-RNA biosynthesis [174—176]. 

D.Y. Jackson, J. Burnier, C. Quan, M. Stanley, J. Tom, J.A. Wells, A designed peptide ligase for total synthesis of ribonuclease A with unnatural catalytic residues. Science 266(5381) (1994) 243-247. 

The solid-phase method was tested with the synthesis of many small peptides,[19] including bradykinin, angiotensin, desaminooxytocin, and the 20-residue S-peptide of ribonuclease A, and was found to be useful and efficient. 

Ribonuclease A (RNase A) was selected as the target enzyme for solid-phase synthesis because its sequence was known (Scheme S), 22 25 and an X-ray structure had been deduced. 24 Importantly, it had been shown that this 124-residue protein could be reduced and unfolded and then reoxidized to re-form the four disulfide bonds with recovery of full enzymatic activity. 25 ... 

Scheme 11 Plan for the Solution Fragment Synthesis of Ribonuclease Tll36la...

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