1. Synthesis of the C-terminal half of thymosin alpha 1 by the polymeric reagent method
M Mokotoff, A Patchornik Int J Pept Protein Res. 1983 Feb;21(2):145-54. doi: 10.1111/j.1399-3011.1983.tb03088.x.
In this report we further show the utility and efficiency of polymer-bound 1-hydroxybenzotriazole (PHBT) as an almost ideal support for the polymeric reagent method of peptide synthesis. This was demonstrated by the synthesis of thymosin alpha 1 (15-28), in which two suitably blocked segments, Boc-Asp (OtBu)-Leu-Lys (2Cz)-Glu (OBzl)-Lys (2Cz)-Lys (2Cz)-OH (3) and Boc-Glu (OBzl)-Val-Val-Glu (OBzl)-Glu (OBzl)-Ala-Glu (OBzl)-Asn-OBzl (2), were prepared entirely by utilizing PHBT activation for each coupling step. After appropriate deblocking of 2, segments 2 and 3 were coupled by the DCC-HOBT method, followed by complete deblocking and ion-exchange chromatographic purification, affording the C-terminal half of thymosin alpha 1, H-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH (1).
2. Primary structure of murine major histocompatibility complex alloantigens: amino acid sequence of the amino-terminal one hundred and seventy-three residues of the H-2Kb glycoprotein
H Uehara, B M Ewenstein, J M Martinko, S G Nathenson, J E Coligan, T J Kindt Biochemistry. 1980 Jan 22;19(2):306-15. doi: 10.1021/bi00543a009.
The amino-terminal 173 residues of the murine histocompatibility antigen H-2Kb have been assigned by using radiochemical methodology. The complete sequence of an 86 residue glycopeptide (CN-Ib), which is one of the five major CNBr fragments of Kb, was determined by analysis of peptides obtained from digests using thrombin and V8 staphylococcal protease. Complete sequences were obtained for the three large thrombic peptides, and these were aligned by using peptides from the V8 protease digest. Alignment of the CNBr fragments was carried out by using [35S]Met-labeled peptides from a tryptic digest of the papain-cleaved H-2Kb molecule. Positive identification was possible for all the common amino acids except Asp (Asp) which was indirectly assigned and which is designated in italics. The sequence obtained in our studies was Gly-Pro-His-Ser-Leu-Arg-Tyr-Phe-Val-Thr-Ala-Val-Ser-Arg-Pro-Gly-Leu-Gly-Glu-Pro-Arg-Tyr-Met-Glu-Val-Gly-Tyr-Val-Asp-Asp-Thr-Glu-Phe-Val-Arg-Phe-Asp-Ser-Asp-Ala-Glu-Asn-Pro-Arg-Tyr-Glu-Pro-Arg-Ala-Arg-Trp-Met-Glu-Gln-Glu-Gly-Pro-Glu-Tyr-Trp-Glu-Arg-Glu-Thr-Gln-Lys-Ala-Lys-Gly-Asn-Glu-Gln-Ser-Phe-Arg-Val-Asp-Leu-Arg-Thr-Leu-Leu-Gly-Tyr-Tyr-(Asn)-Gln-Ser-Lys-Gly-Gly-Ser-His-Thr-Ile-Gln-Val-Ile-Ser-Gly-Cys-Glu-Val-Gly-Ser-Asp-Gly-Arg-Leu-Leu-Arg-Gly-Tyr-Gln-Gln-Tyr-Ala-Tyr-Asp-Gly-Cys-Asp-Tyr-Ile-Ala-Leu-Asn-Glu-Asp-Leu-Lys-Thr-Trp-Thr-Ala-Ala-Asp-Met-Ala-Ala-Leu-Ile-Thr-Lys-His-Lys-Trp-Glu-Gln-Ala-Gly-Glu-Ala-Glu-Arg-Leu-Arg-Ala-Tyr-Leu-Glu-Gly-Thr-Cys-Val-Glu-Trp-Leu-Arg-Arg-Tyr-Leu-Lys. These data represent the longest reported amino acid sequence determined by utilizing radiochemical methodology and provide the first extensive information on the primary structure of murine histocompatibility antigens.
3. Synthesis of two analogs of a cyclic hexapeptide with disulfide bridge corresponding to bovine prothrombin precursor sequence 18-23. Extent of carboxylation by Vitamin K-Dependent carboxylase
D H Rich, M Kawai, H L Goodman, J W Suttie Int J Pept Protein Res. 1981 Jul;18(1):41-51. doi: 10.1111/j.1399-3011.1981.tb02038.x.
The synthesis of two analogs of sequence 18-23 of bovine prothrombin precursor is described. Hexapeptides Boc-Cys (Acm)-Leu-Glu(OBzl)-Glu(OBzl)-Pro-Cys (Acm)-OBzl and Ac-Cys(Acm-Leu-Glu(OBzl)-Glu(OBzl)-Pro-Cys(Acm)-OMe were synthesized in solution by stepwise addition of Boc-amino acids using dicyclohexylcarbodiimide/N-hydroxybenzotriazole as the coupling reagent. The acetamidomethyl groups were cleaved and oxidized, using iodine in methanol, to the protected cyclic disulfide in 62-69% yield. The O-benzyl groups were removed either by treatment with anhydrous hydrogen fluoride or hydrogen bromide in trifluoroacetic acid to give the cyclic hexapeptide disulfides, R1-Cys-Leu-Glu-Glu-Pro-Cys-OR2 where R1 - H or Ac and R2 = H or CH3. The cyclic hexapeptides were evaluated as substrates for vitamin K-dependent carboxylase. Both peptides are unusually poor substrates for the carboxylase, and each appears to inhibit carboxylation of Phe-Leu-Glu-Glu-Leu, a good substrate for the enzyme.
