Transfer factor--a lymphocyte cell surface component.

I Schröder; S Lüneburg

PubMed · 6731201

Transfer factor--a lymphocyte cell surface component.

Abstract

An attempt was made to locate the biologically active component of the DLE in lymphocytes. The test was based on the recovery of sheep cell-rosetting capacity in trypsinized human lymphocytes (recovery assay). Comparisons of the extract from trypsinized leukocytes and the leukocyte supernatant (after trypsination ) yielded the following results: The peptide fraction detached from the cell surface by trypsin (30 min with 0.5 g trypsin/l at 37 degrees C) accounts for most of the TF activity of the whole lymphocytes. Of the two TF activities (fractions II and III), fraction III obviously stems from the cell interior because it cannot be liberated by trypsin. Fraction III is characterized by an unusually high UV absorption quotient (A 260/280), probably due to a large nucleotide content. Trypsination leads to the biologically active TF fraction going into the supernatant. Fraction II consists almost entirely of cell surface peptides. It is relatively easy to separate it cleanly, and it has a high level of biological activity (1 microgram/ml is still detectable).

Explore related subjects

Chromatography, Gel Humans Lymphocytes Palatine Tonsil Rosette Formation Spectrophotometry, Ultraviolet Transfer Factor Trypsin Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

I Schröder, S Lüneburg. Transfer factor--a lymphocyte cell surface component.. https://pubmed.ncbi.nlm.nih.gov/6731201/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed1995

DnaX complex of Escherichia coli DNA polymerase III holoenzyme. The chi psi complex functions by increasing the affinity of tau and gamma for delta.delta' to a physiologically relevant range.

An artificial operon that contains tandem holC-holD genes was used to overproduce a complex of the chi and psi subunits of the DNA polymerase III holoenzyme. Normally insoluble by itself, psi forms a tight soluble complex with chi. A purification procedure that yields pure, active chi psi complex in 100-mg quantities suitable for biophysical studies is reported. Sedimentation equilibrium studies demonstrate that chi psi is a 1:1 heterodimer. The presence of chi psi dramatically lowers the level of delta.delta' required to reconstitute holoenzyme to levels expected in vivo. That chi psi accomplishes this by binding to gamma or tau and increasing their affinity for delta.delta' was demonstrated by surface plasmon resonance using a Pharmacia BIA-core instrument. In the absence of delta.delta', chi psi binds to either the gamma or tau DnaX protein with Kd = 2 nM.

Chromatography, Gel↗

PubMed1995

The polypeptide chain of eukaryotic initiation factor 5A occurs in two distinct conformations in the absence of the hypusine modification.

Eukaryotic initiation factor 5A (eIF-5A) requires posttranslational modification of lysine at position 50 to hypusine for its biological activity. We have expressed an unmodified variant of eIF-5A in Escherichia coli and show that it has structural properties different from those of the native protein in terms of its near- and far-UV circular dichroism spectra and its equilibrium unfolding transition with guanidinium chloride. In contrast to the hypusine-modified protein, which unfolds in a two-state process, the complex unfolding transition of unmodified eIF-5A suggests that this variant occurs in two differently folded conformations, F1 and F2. Both conformations are populated under near-physiological conditions at a ration of 60 to 40, respectively. Equilibrium unfolding consists of parallel events: unfolding of F1 to one or several intermediate states (I), and unfolding of F2 to the unfolded state (U). Although the establishment of each of these individual equilibria is fast, the interconversion is slow at guanidinium chloride concentrations between 0 M and 3 M. Kinetic analysis reveals activation energies of 24.3 kcal mol-1 for the reaction of F1 and F2 and 24.1 kcal mol-1 for the reaction of F2 to F1. Both F1 and F2 possess well-defined secondary and tertiary structure. However, the tertiary structures of the two conformations differ as indicated by their distinct near-UV circular dichroism spectra. These differences may be restricted to the C-terminal part of the protein as 2-dimensional 1H-NMR spectra of unmodified eIF-5A reveal no doubled set of proton resonances for aromatic amino acid and histidine residues, of which almost all are located in the N-terminal region.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Gel↗

PubMed1995

Visible spectrophotometric assay, purification, and molecular properties of a lipoxygenase from eggplant (Solanum melongena Linne) fruits.

We purified a lipoxygenase to homogeneity from eggplant (Solanum melongena Linne) fruits employing the established visible spectrophotometric assay, in which the products of the lipoxygenase-catalyzed reaction, hydroperoxyfatty acids, oxidizes 2,2'-azino-di-[3-ethylbenzothiazoline-(6)-sulfonic acid] diammonium salt in the presence of a catalyst cytochrome c to yield chromophores in the visible region. This allowed for the rapid detection of the lipoxygenase activity and was helpful in accomplishing the efficient purification of the lipoxygenase. The purified lipoxygenase was a monomeric enzyme with a molecular weight of 95,000, s20,w of 5.3 S, and an isoelectric point of 4.4. The specific activity and Km value for the linoleate oxygenation were 7.8 mumol min-1 mg-1 and 0.8 mM, respectively, at 25 degrees C and pH 7.0. The enzyme contained 1.3 g-atom of nonheme iron per enzyme.

Chromatography, Gel↗