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We report here a novel finding that norvaline can be incorporated in place of leucine in recombinant human hemoglobin expressed in Escherichia coli. The presence of the norvaline was confirmed by several analytical methods such as amino acid analysis, peptide mapping, electrospray mass spectrometry, and Edman protein sequencing. It appears that substitution(More)
Many cell-free hemoglobin solutions designed as oxygen-carrying therapeutics produce a hypertensive effect in animals. The response is likely due to oxidation of nitric oxide by hemoglobin. Since the site of oxidation may lie outside the vascular compartment, we tested the hypothesis that polymerization of hemoglobin, rHb1.1, by glutaraldehyde would(More)
Isotope ratio monitoring (IRM) mass spectrometry was used to measure the relative abundance of stable isotopes in several samples of adult human hemoglobin expressed in E. coli, yeast, and human blood. The results showed significant differences in the distribution of (15)N and (13)C isotopes among hemoglobin samples produced in these organisms. This(More)
The reaction of ascorbate with recombinant hemoglobin (rHb1.1) in the presence of differing partial pressures of oxygen was studied. In the presence of 15 000 ppm (1.5%) residual oxygen, ascorbate/oxygen-mediated reactions resulted in an increased rate of autoxidation, modification of the beta-globin, increased oxygen affinity and decreased maximum Hill(More)
A tryptic mapping procedure has been developed for a recombinant hemoglobin (rHb1.1) using an immobilized trypsin cartridge. Apohemoglobin is passed through the trypsin cartridge and the products of the digestion are captured directly onto an in-line C18 reversed-phase column. The peptides are then separated using a gradient elution. This new procedure is(More)
Peptide mapping is a useful technique for identifying posttranslational modifications. However, sometimes artifacts can be introduced during the mapping procedure which can be misleading in identifying the origin and nature of the modifications. During peptide mapping of unalkylated hemoglobins with Staphylococcus aureus V8 proteinase, we found a(More)
Coexpression of di-alpha-globin and beta-globin in Escherichia coli in the presence of exogenous heme yielded high levels of soluble, functional recombinant human hemoglobin (rHb1.1). High-level expression of rHb1.1 provides a good model for measuring mistranslation in heterologous proteins. rHb1.1 does not contain isoleucine; therefore, any isoleucine(More)
An ion trap mass spectrometer equipped with an electrospray source was used to examine the relative thermodynamic stabilities of various hemoglobins with respect to both tetramer dissociation and hemin dissociation. The results demonstrated that the stability of hemoglobin molecules can be differentiated by the amount of applied collision-induced(More)
Recombinant human hemoglobin rHb1.1 has been genetically engineered with the replacement of the wild-type valine residues at all N-termini with methionine, an Asn 108 Lys substitution on the beta globins, and a fusion of the two alpha globins with a glycine linker. When rHb1.1 was expressed in Escherichia coli, methylation of the N-terminal methionine of(More)
We report the measurements of picometer vibration amplitudes produced by a piezo mirror in an interferometric setup, using a GaAs:Cr photoconductive device. The moving light fringes (gratings) induce in this new detector periodic photocurrents characterized by efficient suppression of the low-frequency drifts of the working point and low sensitivity to the(More)