David H. Schlesinger

The amino acid sequence of thymopoietin II

The amino acid sequence of bovine thymopoietin II is presented. This T cell differentiating hormone of the thymus is a single 49 amino acid polypeptide chain of 5562 daltons. There is microheterogeneity at the C terminus with approximately two thirds of the molecules lacking the C terminal arginine found on the remaining molecules. Determination of the primary structure of thymopoietin II was facilitated by a long automated sequenator run on thymopoietin II coupled to 2-isothiocyanonaphthalene-4,8-disulfonic acid (NITC), tryptic cleavage of maleated thymopoietin II to yield the overlapping C terminal peptide, and efficient manual sequencing of this peptide using benzene extractions to minimize extractive losses of peptide.

Chemical Synthesis of a Peptide Fragment of Thymopoietin II that Induces Selective T cell Differentiation

Thymopoietin is a polypeptide hormone of the thymus that consists of a 49 amino acid polypeptide chain of 5562 daltons. A peptide corresponding to positions 29-41 of bovine thymopoietin II was synthesized by the Merrifield solid-phase technique. This peptide was shown to have a purity (correct sequence) of 96% by amino acid and C terminal analyses and by a complete determination of the amino acid sequence by manual Edman degradations. It displayed a selectivity of action similar to that of thymopoietin itself, inducing the differentiation of T lymphocytes but not of complement receptor (CR+) B lymphocytes. Although a number of substances induce the differentiation of both T cells and CR+B cells under the conditions of assay in vitro, only thymopoietin and the synthetic peptide described in this report have been shown to induce the differentiation of T cells selectively. Our data establish that the key residues involved in the active site of thymopoietin are present within a synthetic polypeptide which constitutes a minor portion of the amino acid sequence of thymopoietin. Since this peptide had 3% activity by comparison with thymopoietin, the tertiary structure of thymopoietin may be required for optimal configuration of the active site to produce full biological activity.

Complete amino acid sequence of ovine neurophysin-III

David H. SCHLESINGER, Michael ERNST, Ann NICHOLAS*, W. B. WATKINS** and Roderich WALTER*** Department of Medicine, Massachusetts General Hospital, Boston, Mass. 02115, USA *Department of Biophysics, University of Chicago, Chicago, Ill. 60637, USA; **Postgraduate School of Obstetrics and Gynaecology, University of Auckland, Auckland, New Zealand; ***Department of Physiology, University of Illinois at the Medical Center, Chicago, Ill. 60612, USA

A comparative study of partial neurophysin protein sequences of cod, guinea pig, rat and sheep

David H. SCHLESINGER, B. T.. PICKERING*, W. B. WATKINS**, J. C. PEEK**, L. G. MOORE**, T. K. AUDHYA+ and Roderich WALTER+ Endocrine Unit, Dept. ofMedicine, Mass General Hospital, Boston, MD 02114; *Dept. of Anatomy, Univ. of Bristol, Bristol, U.K.; **Postgraduate School of Obstetrics and Gynaecology, Univ. of Auckland, Auckland, New Zealand; +Department of Physiology and Biophysics, Univ. of Illinois Med. Center, Chicago, IL 60612, USA

Localization of translation initiation in the message for E.coli UDP-galactose 4-epimerase: The amino terminal sequence

Abstract The amino acid sequence of E. coli UDP-galactose 4-epimerase has been determined through the amino-terminal 28-amino acid residues using an automated protein sequenator. Alignment of UDP-galactose operon messenger RNA and the amino acid sequence of epimerase demonstrates that the first 26 bases in the mRNA are transcribed but do not take part in translation of epimerase.

Chemical synthesis of a hexadecapeptide segment of ubiquitin that activates adenylate cyclase and induces lymphocytes to differentiate

A hexadecapeptide corresponding to positions 59–74 of ubiquitin was synthesized and purified. The peptide was characterized by its mobility in TLC and electrophoresis, amino acid sequence and composition, and molar rotation. The peptide possessed approximately 40% activity compared with native ubiquitin in each of 3 biological assays in vitro: a) thymocyte induction, b) B cell induction and c) elevation of intracellular cyclic AMP levels in sarcoma 180 cells.