Controlled modification of horseradish peroxidase with an apolar polymer chain (see figure) by cofactor reconstitution leads to giant amphiphiles, which form vesicular aggregates in aqueous solution.

The application of analytical capillary, carrier-free isotachophoresis as a rapid method (approx. IO-15 min per run) for the simultaneous determination of anions present in peptides (as countenon, contaminating ion or peptide anion) is described. Only small amounts of material, approx. 0.1 -1.0 mg, are necessary to obtain information on the nature of the anion (qualitative) and o f the amount o f anion present (quantitative aspect).Key words: analytical capillary isotachophoresis; peptides; simultaneous qualitative and quantitative determination of anions.

The synthesis is described of several fragments of the neurohypophyseal nonapeptide hormones arginine vasopressin and oxytocin. One group of fragments is characterized by the presence of an asymmetrical disulfide (a cystine residue in position 6), a second group consists of dimeric (symmetrical disulfides) fragments. As common intermediates, peptides containing an S‐tritylcysteine residue were synthesized by the fragment condensation approach. Treatment with methoxycarbonylsulfenyl chloride followed by reaction with the free thiol function of cysteine gave the asymmetrical disulfides, while treatment of the S‐tritylcysteine containing peptide with iodine resulted in the corresponding dimers. Peptides with an N‐terminal glutamine residue (position 4) were found to convert spontaneously into the corresponding pyroglutamic acid products.

Die Synthese der Titelverbindungen (VI), (VII), (XIa), (Xlc) (Arginin‐Vasopressin‐Fragmente) bzw. (IX), (XIb), (Xld) (Oxytocin‐Frag‐ mente) wird beschrieben.