Notes: Synenkephalin (SYN), the nonopioid amino-terminal portion of proenkephalin (PRO), is stable and well conserved in mammals and therefore a promising marker for PRO systems. We immunized rabbits with synthetic [Tyr63]SYN(63–70)-octapeptide, coupled by glutaraldehyde to bovine serum albumin. In radioimmunoassay (RIA) using antiserum no. 681, [Tyr63]SYN(63–70)-octapeptide as standard, and 125I-[Tyr63]SYN(63–70)-octapeptide as tracer, the IC50 was ∼51 fmol/100-μl sample at equilibrium or 12 fmol/100 μl in disequilibrium, and the sensitivity was ∼3 fmol/100 μl. Cross-reactivity of the assay was 100% with [Cys63]SYN(63–70)-octapeptide and with bovine adrenal 8.6-kilodalton peptide digested with trypsin and carboxypeptidase B, but 〈 0.1% with transforming growth factor-alpha, 〈inlineGraphic alt="leqslant R: less-than-or-eq, slant" extraInfo="nonStandardEntity" href="urn:x-wiley:00223042:JNC434:les" location="les.gif"/〉 2 × 10-6 with Leu-Leu-Ala [SYN(68–70)-tripeptide], and ≪ 10-6 with all other peptides tested. Therefore in RIA this antiserum is specific for the free carboxyl terminus of SYN. Because the peptide detected after enzyme digestion is the complete SYN(63–70)-octapeptide, we refer to the RIA as an assay for SYN(63–70). Tissue extracts were made in 1 M acetic acid, dried, reconstituted in Tris-CaCl2, and digested sequentially with trypsin plus carboxypeptidase B. Extracts from bovine corpus striatum gave SYN(63–70) RIA dilution curves parallel to the standard curve both before and after digestion. Digestion increased the amount of immunoreactive SYN(63–70) in striatum by a factor of 1.5–2.0. The ratio of total immunoreactive [Met5]enkephalin to total immunoreactive SYN(63–70) (after sequential digestion) was ∼6:1. At least 90% of the immunoreactive SYN(63–70) in extracts of bovine caudate nucleus eluted from Sephadex G-100 with an apparent molecular weight equal to that of bovine PRO(1–77). Using the new RIA we were able to detect and characterize SYN processing for the first time in extracts of whole rat brain, human globus pallidus, and human pheochromocytoma. Results in these tissues were similar to those in cattle, in that most stored SYN had been processed to a free carboxyl terminus. Since the C-terminal octapeptide of SYN is practically identical in all known mammalian PRO, antiserum no. 681 should be useful for detecting, measuring, and purifying SYN from various mammals, including human beings.

Notes: [Auszug] Lymphocyte polyclonal activation is a generalized mechanism of immune evasion among pathogens. In a mouse model of Trypanosoma cruzi infection (American trypanosomiasis), reduced levels of polyclonal lymphocyte responses correlate with resistance to infection and cardiopathy. We report here the ...