The plasma tripeptide glycyl-L-lysine (GHL), when added at nanomolar concentrations to a wide group of cultured systems, produces a disparate set of responses ranging from the stimulation of growth and differentiation to outright toxicity. Such diverse actions imply that this tripeptide mediates some basic biochemical function common to many types of cells and organisms. During the isolation of GHL we found the compound to co-isolate through a number of steps with approximately equimolar copper and about 1/5 molar iron. Maximal effects on hepatoma cells (HTC4) were seen when the peptide was added with copper and iron to the growth medium. Structure-function studies revealed that several tripeptides with a histidyl-lysyl linkage were nearly as active as GHL. The association of GHL with copper and a homology similarity between the tripeptide and the copper transport sites on albumin and alpha-fetoprotein, where the cupric atom is bound to a histidyl residue adjacent to a basic residue, suggested that GHL may act as a copper transport factor. We report here that the tripeptide readily forms complexes with copper(II) and enhances the uptake of the metal into cultured hepatoma cells.

The complete amino acid sequence of the light chain of human blood coagulation factor X has been determined by automated Edman degradation of peptides isolated from chemical and enzymatic digests of the carboxymethylated light chain. The protein consists of 139 amino acid residues, which include 11 residues of gamma-carboxyglutamic acid. The first 100 residues of the human factor X light chain exhibit approximately 80% homology when compared to the amino-terminal sequence of bovine factor X light chain. This homology decreases to approximately 50% in the remaining 39 residues of the carboxyl-terminal region of the protein. Proton nuclear magnetic resonance spectroscopy and mass spectrometry analyses of isolated residue 63 identified this residue as L-erythro-beta-hydroxyaspartic acid, a hitherto unrecognized amino acid in proteins. Evidence is also presented for the presence of this residue in the corresponding regions of the light chains of bovine factor X and bovine protein C. The biological function of beta-hydroxyaspartic acid in these proteins is unknown.

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Optical, electron paramagnetic resonance, and electron spin-echo envelope spectroscopies were used to examine the structure of the Cu(II) complex of glycyl-L-histidyl-L-lysine (GHL) in solution. At neutral pH, GHL forms a mononuclear 1:1 Cu(II) compound having an EPR spectrum resembling that of Cu(II) equatorially coordinated by two or three nitrogen atoms. Electron spin-echo studies demonstrate that one of these is located in the histidyl imidazole ring. A pH titration of Cu(II)-GHL shows three optical transitions with apparent pKs of 3.6, 9.2 and 11.4 and molecularities, with respect to protons, of 2, 2, and 1, respectively. At the lowest pK, GHL binds Cu(II), forming the species present at physiological pH. At elevated pH, spectroscopic experiments suggest that an alteration of the Cu(II) structure occurs, yet the bound imidazole is retained. These solution studies are consistent with nitrogen coordination of Cu(II) in Cu(II)-GHL, but the solid-state polymeric structure, with oxygen-bridged Cu(II) pairs as previously determined by X-ray crystallographic analysis [Pickart, L., Freedman, J. H., Loker, W. J., Peisach, J., Perkins, C. M., Steinkamp, R. E., & Weinstein, B. (1980) Nature (London) 288, 715-717; C. M. Perkins, N. J. Rose, R. E. Steinkamp, L. H. Jensen, B. Weinstein, and L. Pickart, unpublished results], does not exist in solution.

and (15). 15we conform to the metric and representation of the y matrices used by S. Schweber, An Introduction t o Relativistic Quantum Field Theory (Harper and Row, -New York, 1961). 1 6~. S, Ginsberg, Phys. Rev. D 1, 229 (1970). Note: The factors of $ multiplying the dilogarithms in the second line of Eq. (20) a r e copying e r r o r s and should be omitted. The numerical results a r e not significantly changed (generally by 0.0 to 0.3% in the Dalitz plot). A corrected version of Fig. 2(a) i s glven in Fig. 1 of _ t h i s paper.'7~nfrared-divergent terms, which cancel exactly when all the contributions to the radiative c o r r e c t~o n s a r e added, have been omitted.We present a straightforward method for calculating the amplitudes of the various JMLS states in the final 3n system of the reaction nN -nnW, assuming a Deck-model form for the production process. This calculation allows us to study relative phases of different partial waves, and the nucleon spin structure of the production amplitudes, in an unambiguous fashion. We find that the magnitudes and phases of 3n partial waves obtained by this method agree reasonably well with those obtained by applying an experimental fitting program to Monte Carlo events generated using the Deck formula; this may be interpreted a s a check on the assumptions of the fitting program. Likewise, the magnitudes and phases agree reasonably well with those obtained from the data, confirming the belief that the Ai and A g effects a r e probably produced by the Deck mechanism. In the rest system of the three pions, only one nucleon helicity-amplitude combination i s dominant. The method of analysis can be applied to similar models for other production reactions.