Peptide synthesizer use

PEPTIDE SYNTHESES USING N-ETHYL-5-PHENYLIS0XAZ0LIUM-3 -SULF0NATE CARBOBENZOXY-l-ASPARAGINYL-l-LEUCINE METHYL ESTER AND JV-CARBOBENZOXY-3-HYDROXY-l-PROLYLGLYCYLGLYCINE ETHYL ESTER... 

Carbodiimide peptide synthesis. 1 -Hydroxybenzotriazole (HOBt) is frequently used to suppress racemization in peptide syntheses using carbodiimides. Copper(II) chloride decreases racemization, but also depresses the yield markedly. By judicious use of both additives, racemization can be prevented with only slight effect on the yield. 

Caged peptides (NPY and angiotensin II) containing Tyr[Bzl(2-N02) were synthesized on an automated solid-phase peptide synthesizer using Fmoc chemistry and cleaved from the resin by treatment with TFA. Crude peptides were purified by semipreparative HPLC with a gradient phase of 0.1% TFA and MeCN. For fractions containing peptides, the eluant was not passed through the UV monitor to avoid potential photolysis. The collected peptide was examined by analytical HPLC and MS. 

Ikota (20) reported the first solid-phase synthesis of motilin in 1980, and the overall yield was 1.8%. Coy et al. (21) improved the synthesis and got a 10% yield. Coy s synthesis was carried out on a Beckman model 990 automatic peptide synthesizer using A -Boc chemistry. Motilin was assembled stepwise on a 1% cross-linked BHA resin with Boc-a-benzyl-Glu as the first amino acid to be incorporated. In this manner, C-terminal Gin could be directly formed on HE cleavage of the final peptide from the resin. The detailed coupling schedule is shown in Table 2 (22). The symmetric anhydride method was used for... 

With the same number of chemical steps, the diversity and number of peptides synthesized using light-directed, spatially addressable chemical synthesis depends, among other factors, on the patterns of the photohthographic masks used for each photodeprotection. Different masking strategies can be used. 

PEPTIDE SYNTHESES USING iV-ETHYL-6-PHENYLIS0XAZ0LIUM-3 -SULF0NATE CARB0BENZ0XY-L-ASPABAGINY1-I.-LEUCINE METHYL ESTER AND N-CARBOBENZOXY-8-HYDROXY-... 

Table II. Peptides Synthesized Using the Shadchan Method...

Polypeptoids are similar to polypeptides except the side chains are attached to the amide nitrogen of the peptide backbone instead of the a -carbon (Figure 12.6). Peptoids are synthesized by solid-phase synthesis on a peptide synthesizer using a submonomer approach that proceeds by adding each monomer in a two-step process. With this method, many different side chain groups... 

A very convenient laboratory-scale procedure for making peptides is the use of automated peptide synthesizers using t-boc or f-moc chemistry (132). However, the expense... 

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