Minoru Hiramoto

Synthesis of the proposed structure of viscosin

Abstract Two diastereoisomeric d -β-hydroxydecanoyl hexapeptides, ( I ) and ( II ), were synthesized. Although the structure ( I ) has been proposed for viscosin, neither compound was not identical with viscosin. The results therefore suggest that the structure of viscosin must be reinvestigated.

Syntheses and enzymic hydroxylation of protocollagen model peptides containing glutamyl or leucyl residue.

Protocollagen-proline hydroxylase converts the prolyl residues in protocollagen to hydroxyprolyl residues by an oxygenase mechanism [ l-3] . ProtocolIagen model peptides, (Pro-Cly-Pro), [4] or (ProPro-Gly), _-20 [5], were used as synthetic substrates of this enzyme. Studies on the enzymic hydroxylation of (Pro-Pro-Gly), with defined molecular weight (n = I-20) suggested that the prolyl residues in nonterminal -Pro--Pro-Glyunits were more easily hydroxylated than those at the terminal and that the triple stranded conformation in larger peptides was unfavourable for the hydroxylation [5). As natural protocollagen has a molecular weight of about 140 000 161, most of the pro&y1 residues to be hydroxylated are at the non-ternlinal -X-Pro-Glysequence. The amino acid residues at the X-position of the above sequence may also affect the hydroxylation. No hydroxylation was observed with the repeating tripeptides(Gly-Pro-Gly)i_4, however, synthetic (Ala-Pro-Gly), _ s were reported to be hydroxylated [7]. The present work was carried out to examine the effect of glutamyl and leucyl residues at the X-position of -X-Pro-Glysequence on the enzymic hydroxylation.

A study of some new and useful n-terminal groups in mass spectrometry of peptides : The use of 3-hydroxyalkanoyl and unsaturated acyl groups☆

Abstract Using model peptides ranging from tri- to dodecapeptides, the utility of several new N-protecting groups, i.e., 3-hydroxyalkanoyl and δ 2 -acyl groups including Oct(OH), Dec(OH), Dod(OH), Myr(OH), Pal(OH), Ste(OH), Δ 2 -Dec, Cro, and Cin, for mass spectrometric sequence analysis were examined. Among these, the Dec(OH)- and Δ 2 -Dec peptide derivatives were found to be superior to the hitherto reported Ac or Dee derivatives, since they gave comparable or sometimes better mass spectra. Particularly the Dec(OH) derivatives yielded two series of sequence peaks (as doublets of 18 mass units apart) ascribable to partial dehydration of the protecting group, the fact which makes the recognition of sequence determining peaks much easier. The Cro and Cin derivatives also gave mass spectra comparable to those of the corresponding Ac or Dec ones, except in a few cases where (Pro-Pro-Gly) 2–4 were model peptides. Permethylation technique can also be effectively applied to the all new acyl derivatives for the mass spectrometric sequence studies.