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The ferredoxin (Fd) molecule is a small non-mammalian immunogenic protein containing 55 amino acid residues with only two major antigenic determinants located with the NH2-terminal heptapeptide and the COOH-terminal pentapeptide. Selective enzyme cleavages of Fd with either trypsin or carboxypeptidase A result in the inactivation of the antigenic determinants by the removal of a tripeptide at the NH2-terminal and two amino acid residues at the COOH-terminal, effectively leaving 52 and 53 amino acid fragments respectively, each containing a single antigenic determinant. Fd digested with both enzymes yielded a 50 amino acid peptide with both determinants inactivated. Purity of these digests was assessed using monoclonal antibodies in standard and antigen-blocking ELISAs. The doubly digested peptide had virtually no reactivity with anti-Fd sera, reconfirming that the central cysteine-rich region is serologically silent. It was found that the sum of the reactivities of the N- and C-determinant-bearing peptides as equal to that of the native Fd and that the ratio of the reactivities could be used to assess determinant selectivity in the response to Fd in congenic recombinant strains of mice. This method was used in mapping the determinant selectivity in the antibody response to the MHC of mice to the left of the I-B subregion. Use of the B10.HTT strain indicated that separate genes mapping to the same subregion code for the magnitude of the antibody response and the determinant selectivity of the response.

This study of protease-catalyzed peptide synthesis reports the preparation of the COOH-terminal octapeptide amide of cholecystokinin. The octapeptide was assembled by chemical condensation of two tetrapeptide segments that had been synthesized through the concerted catalytic reactions of several proteases of different specificities. The resulting octapeptide derivative was subjected to catalytic transfer hydrogenation, followed by sulfation of its tyrosine residue and removal of the N alpha-protecting group. The homogeneous target peptide was obtained after purification via partition chromatography, gel filtration, and ion-exchange chromatography. The synthetic octapeptide stimulated amylase release from pancreatic acinar cells.

Fibrinolytic response to venous occlusion and other clotting parameters were studied in 34 obese children and 16 controls. The obese children (mean age 9 2/12 years) had a mean overweight of 51.8% +/- 15.6, higher blood glucose and cholesterol levels, and increased baseline and glucose-induced insulinemia. However, baseline ELT did not differ significantly; ELT after 5 min venous occlusion was 203.2 +/- 110.9 min in the obese children and 114.7 +/- 67.9 min in the control group (p less than 0.01) with a mean percent decrease respectively of 14.9% and 29.2%. Poor fibrinolytic responders did not correlate with age, overweight, or metabolic indices. Lower levels of ATIII (p less than 0.01) and no changes in F VIII: C and F VIII: R Ag were also found in the obese. Furthermore, in a larger group of 84 prepubertal obese children (mean age 10 years; mean overweight 48.2%) and in 39 normal prepubertal children (mean age 10 4/12 years) we also studied platelet aggregation capacity according to Breddin. This parameter was altered in a high proportion of the obese children (p less than 0.05). The obese children were also poor fibrinolytic responders, similarly to obese adults, and exhibited early alteration of the clotting balance.